



















                               SkyMap v1.3 User Guide
                               SkyMap v1.3 User Guide
                               SkyMap v1.3 User Guide

                                    C A Marriott
                                    C A Marriott
                                    C A Marriott

                                      May 1993
                                      May 1993
                                      May 1993











                        _______
                   ____|__     |                (R)
                --|       |    |-------------------
                  |   ____|__  |  Association of
                  |  |       |_|  Shareware
                  |__|   o   |    Professionals
                -----|   |   |---------------------
                     |___|___|    MEMBER




                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott














                      Respectfully dedicated to the memory of:

                                  Francis R Scobee
                                   Michael J Smith
                                  Ellison S Onizuka
                                  Judith A Resnick
                                   Ronald E McNair
                                   Gregory Jarvis
                                 S Christa McAuliffe

              the crew of Challenger flight STS 51-L, 28th January 1986
                and to all who have lived - and died - for The Dream.


                    "Oh, I have slipped the surly bonds of earth,
                  And danced the skies on laughter-silvered wings;
                 Sunward I've climbed and joined the tumbling mirth
                  Of sun-split clouds -- and done a hundred things
               You have not dreamed of -- wheeled and soared and swung
                     High in the sunlit silence. Hov'ring there,
                    I've chased the shouting wind along and flung
                    My eager craft through footless halls of air.
                      Up, up the long, delirious, burning blue
                 I've topped the wind-swept heights with easy grace,
                       Where never lark, or even eagle, flew;
                   And, while with silent, lifting mind I've trod
                      The high, untrespassed sanctity of space,
                   Put out my hand, and touched the face of God."

                                      "High Flight"   John G Magee Jr, 1943




                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott

                               Table of Contents

          Introduction................................................1
              What is Shareware? .....................................2
              Disclaimer Agreement ...................................2
              ASP Ombudsman Statement ................................3
              Contacting the Author ..................................3
              Registering SkyMap .....................................4
              System Requirements ....................................6
          Setting Up SkyMap...........................................7
              Installing the Software ................................7
              Configuring SkyMap for your Location ...................8
          Horizon Maps................................................11
              Drawing a Horizon Map ..................................11
              Horizon Map Options ....................................11
                   Viewpoint .........................................11
                   Time ..............................................12
                   Observer ..........................................12
                   Stars .............................................13
                   Star Labels .......................................14
                   Labels ............................................14
                   Constellation Names ...............................16
                   RNGC Objects ......................................16
                   Colours ...........................................17
                   Reduce Positions ..................................17
                   Draw ..............................................18
              Using the Horizon Map ..................................18
                   Setting the Visibility of Objects .................18
                   Changing the map scale ............................18
                   Identifying Objects on the Map ....................19
                   Zooming to an Area Map ............................23
                   Printing the Map ..................................24
          Sky Area Maps...............................................26
              Drawing a Sky Area Map .................................26
              Sky Area Map Options ...................................26
                   Viewpoint .........................................26
                   Time ..............................................27
                   Observer ..........................................27
                   Stars .............................................28
                   Stars Labels ......................................29
                   Constellation Names ...............................30
                   RNGC Objects ......................................30
                   Colours ...........................................31
                   Draw ..............................................31
              Using the Sky Area Map .................................32
                   Setting the Visibility of Objects .................32
                   Changing the map scale ............................32
                   Identifying Objects on the Map ....................32
                   Zooming to an Area Map ............................32
                   Printing the Map ..................................33
          Displaying Pictures.........................................34
              Picture Formats ........................................34
              Displaying Pictures Manually ...........................34
              Displaying Pictures Automatically ......................34

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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott

              Obtaining Picture Files ................................35
          Appendix A:  Data Sources and Precision.....................37
              Stars ..................................................37
              Planets and Sun ........................................37
              Moon ...................................................37
              Non-Stellar Objects ....................................38
              Time Corrections .......................................38
          Appendix B:  Dreyer Object Descriptions.....................40
          Appendix C:  SkyMap Release History.........................44














































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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott



          Introduction
          Introduction
          Introduction

          SkyMap is a "Planetarium" program for Microsoft Windows version
          3.1 or later.  It will display a map of the sky as seen from any
          point on Earth for any date between 4000BC and 8000AD.  Two
          different types of map can be drawn - a "Horizon" map showing the
          observer's local horizon, and a "Sky Area" map showing a detailed
          view of a small area of the sky.  You can get information about
          any object displayed on the map by simply pointing at the object
          with the mouse and clicking the button.  The display of
          additional information, such as constellation figures or star
          labels can be switched on and off with a click of the mouse
          button, making it easy to see exactly what you want without being
          overwhelmed by unwanted information.  When you have the map
          exactly as you want it, you can print it on any printer supported
          by Windows, in either black and white or colour.

          SkyMap can also display photographic images, supplied in the form
          of GIF or Windows bitmap files.   Thousands of such images are
          freely available on bulletin boards and commercial information
          systems such as CompuServe and BIX.  This allows you to build up
          your own personal library of astronomical photographs which,
          coupled with the map displays, really helps to bring the sky to
          life!

          There are a number of planetarium programs available today.
          Unlike some of these, SkyMap makes no claims of blinding
          calculation speeds.  Instead, what SkyMap concentrates on is
          accuracy.  When writing SkyMap I've used the most accurate
          methods available to me for all the calculations.  This accuracy
          makes SkyMap equally suited for both the novice astronomer who
          just wants to know "what's that bright object up there?" and the
          serious amateur or professional astronomer who wants a detailed
          "finder chart" for a faint galaxy.  Appendix A of this manual
          describes the data sources SkyMap uses, and gives an indication
          of the likely errors in its calculations.

          SkyMap carries out its calculations in as efficient as manner as
          possible, but it never compromises accuracy for the sake of
          speed.  An increase in speed can always be achieved by using a
          faster computer!  Having said all that, the speed is still
          reasonable; on the author's 33MHz 486-based PC for example, the
          horizon map, with default settings, is computed and drawn in
          about 5 seconds.

          Although I am releasing SkyMap as Shareware, I quite appreciate
          that you may not consider it worth paying any money for in its
          current form.  I would obviously like to be paid the registration
          fee - I've put a great deal of work into this software - but I
          would still appreciate receiving your feedback on the program
          even if you feel it's not currently worth registering.  If you do
          feel this way I'd like to know what, if anything, I could do to
          make you change your mind in the future!


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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott



          Whilst developing SkyMap I've received the help and encouragement
          of a number of people.  I'd especially like to thank David Webber
          for many useful suggestions and help with the mathematical
          problems I encountered, and Steve Moshier for generously
          consenting to allow me to use many of his coding ideas for
          various astronomical calculations.  Finally, I'd like to thank
          Jean Meeus for writing the book "Astronomical Algorithms"
          (Willman-Bell, 1991), without which this program would never have
          existed.



          What is Shareware?
          What is Shareware?
          What is Shareware?

          Shareware distribution gives users a chance to try software
          before buying it. If you try a shareware program and continue
          using it, you are expected to register. Individual programs
          differ on details -- some request registration while others
          require it, some specify a maximum trial period. With
          registration, you get anything from the simple right to continue
          using the software to an updated program with printed manual.

          Copyright laws apply to both Shareware and commercial software,
          and the copyright holder retains all rights, with a few specific
          exceptions as stated below. Shareware authors are accomplished
          programmers, just like commercial authors, and the programs are
          of comparable quality. (In both cases, there are good programs
          and bad ones!) The main difference is in the method of
          distribution. The author specifically grants the right to copy
          and distribute the software, either to all and sundry or to a
          specific group. For example, some authors require written
          permission before a commercial disk vendor may copy their
          Shareware.

          Shareware is a distribution method, not a type of software. You
          should find software that suits your needs and pocketbook,
          whether it's commercial or Shareware. The Shareware system makes
          fitting your needs easier, because you can try before you buy.
          And because the overhead is low, prices are low also. Shareware
          has the ultimate money-back guarantee -- if you don't use the
          product, you don't pay for it.


          Disclaimer Agreement
          Disclaimer Agreement
          Disclaimer Agreement

          Users of SkyMap must accept this disclaimer of warranty:

          "SkyMap is supplied as is.  The author disclaims all warranties,
          expressed or implied, including, without limitation, the
          warranties of merchantability and of fitness for any purpose. The
          author assumes no liability for damages, direct or consequential,
          which may result from the use of SkyMap."



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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          SkyMap is a "shareware program" and is provided at no charge to
          the user for evaluation.  Feel free to share it with your
          friends, but please do not give it away altered or as part of
          another system.  The essence of "user-supported" software is to
          provide personal computer users with quality software without
          high prices, and yet to provide incentive for programmers to
          continue to develop new products.  If you find this program
          useful and find that you are using SkyMap and continue to use
          SkyMap after a reasonable trial period, you must make a
          registration payment to Chris Marriott.  The registration fee
          will license one copy for use on any one computer at any one
          time.  You must treat this software just like a book.  An example
          is that this software may be used by any number of people and may
          be freely moved from one computer location to another, so long as
          there is no possibility of it being used at one location while
          it's being used at another. Just as a book cannot be read by two
          different persons at the same time.

          Commercial users of SkyMap must register and pay for their copies
          of SkyMap within 30 days of first use or their license is
          withdrawn.  Site-License arrangements may be made by contacting
          Chris Marriott.

          Anyone distributing SkyMap for any kind of remuneration must
          first contact Chris Marriott at the address below for
          authorisation. This authorisation will be automatically granted
          to distributors recognised by the ASP as adhering to its
          guidelines for shareware distributors, and such distributors may
          begin offering SkyMap immediately (However Chris Marriott must
          still be advised so that the distributor can be kept up-to-date
          with the latest version of SkyMap.).

          You are encouraged to pass a copy of SkyMap along to your friends
          for evaluation.  Please encourage them to register their copy if
          they find that they can use it.



          ASP Ombudsman Statement
          ASP Ombudsman Statement
          ASP Ombudsman Statement

          This program is produced by a member of the Association of
          Shareware Professionals (ASP).  ASP wants to make sure that the
          shareware principle works for you. If you are unable to resolve a
          shareware-related problem with an ASP member by contacting the
          member directly, ASP may be able to help. The ASP Ombudsman can
          help you resolve a dispute or problem with an ASP member, but
          does not provide technical support for members' products.  Please
          write to the ASP Ombudsman at 545 Grover Road, Muskegon, MI 49442
          or send a CompuServe message via CompuServe Mail to ASP Ombudsman
          70007,3536.


          Contacting the Author
          Contacting the Author
          Contacting the Author



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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          If you have any questions about SkyMap, or you require support,
          you can contact me in a number of different ways:

          1.  If you have the capability, e-mail is the best way to contact
          me.  It's quick, and a written request is always easiest to deal
          with.  I can be reached at any of the following addresses, in no
          particular order of preference:

               Internet:      chris@chrism.demon.co.uk
               CompuServe:    100113,1140

          2.  If you prefer to write me a letter, my postal address is:

               Chris Marriott
               9, Severn Road
               Culcheth
               Cheshire WA3 5ED
               United Kingdom

          I have no intention of moving, so that address should apply for
          the foreseeable future!  Note that this is also the address to
          which registration fees should be sent.

          3.  Finally, if you would like to speak to me in person, you can
          telephone me on the following number:

               Within the UK: 0925 76 4131
               International: +44 925 76 4131

          Please call at the weekend, or between 6pm and 10pm GMT during
          the week.  Please also remember that I am in the UK, and consider
          the time difference if you're calling from overseas.  I would not
          welcome a call at 3am if you happen to be on the west coast of
          the USA and you decide to phone me at 7pm local time!

          Please feel free to contact me - I'd love to receive any comments
          you may have on the program, or suggestions as to how it could be
          improved.


          Registering SkyMap
          Registering SkyMap
          Registering SkyMap

          As described above, SkyMap is not free software.  It is shareware
          and, as such, you must register it if you find it useful after a
          reasonable trial period.  I would suggest that 30 days is
          reasonable for such a trial.  The shareware concept is based on
          trust, and I trust you to pay for this program if you are using
          it.  There are several different levels of registration
          available:

          Personal:  Personal registration allows the program to be used by
          one person.  You may install the software on any number of
          computers, as long as only one will be in use at any one time.



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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          Club:  Club registration allows free use by all members of an
          astronomy club (or, indeed, any other sort of club!), on any
          number of computers, whilst at club meetings.  Any club member
          who wants to use the program at home is still expected to
          register the program personally.

          Educational:  Educational registration allows unrestricted
          copying and use of SkyMap within a school, college, university,
          or other educational establishment.

          Corporate??:  Frankly, I can't imagine any corporate use for
          SkyMap, but if you are a corporate user and you'd like to
          negotiate a site license for use of SkyMap, please contact me to
          discuss it!

          For full information about registration, including details of
          current prices and methods of payment, please refer to the
          separate registration form "REGISTER.TXT".

          If you have access to CompuServe you may wish to take advantage
          of the on-line shareware registration facilities available to
          quickly and easily obtain a personal registration for SkyMap.  To
          do so, enter the command "GO SWREG" at any "!" prompt, and select
          program ID 876.  The registration fee will be charged directly to
          your CompuServe account and, especially if you live in a country
          other than the UK, you will avoid the inconveniences caused by
          having to deal with foreign currency.

          In return for registering SkyMap you will receive:

          1.  A registered copy of the latest version of SkyMap, with the
          registration reminder removed from the "About SkyMap" box.

          2.  A bound, illustrated manual.

          3.  A much larger star database.

          4.  Unlimited lifetime support, using any of the methods
          described in the "Contacting the Author" section of this manual.

          5.  The right to purchase, for a small fee, additional materials
          which enhance the use of SkyMap.

          6.  The right to upgrade to a registered copy of the latest
          version of SkyMap, at any time,  for a nominal fee.  You may do
          this as often as you wish.

          7.  A lifetime money-back guarantee.  If you ever find a serious
          bug in SkyMap which makes it unusable, your registration fee will
          be immediately refunded, with no questions asked.






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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          System Requirements
          System Requirements
          System Requirements

          SkyMap requires Microsoft Windows version 3.1 or above to run.
          It will not work with Windows 3.0 or earlier.  Windows 3.0 had a
          number of major flaws, and early on in the development of SkyMap
          I made the decision not to support it.  I apologise if this
          inconveniences you, but supporting Windows 3.0 would have quite
          severely restricted certain aspects of SkyMap's operation.

          You do not actually need a maths coprocessor to run SkyMap, but
          it will run very slowly without one.  SkyMap does a great deal a
          great deal of trigonometry while creating maps, and use of a
          coprocessor can speed up this process by a factor of ten or more!

          SkyMap will work with any type of video card supported by
          Windows.  For best results, VGA or better is recommended.  If you
          want to display photographic images you really need a card and
          monitor capable of displaying 256 (or more) colours at the same
          time, such as a "SuperVGA", "High Colour" or "True Colour" video
          card..

          Maps can be printed, in either black and white or colour, on any
          type of printer supported by Windows.  The best results will be
          obtained from a laser or high-quality ink-jet printer, but
          perfectly acceptable results will be obtained from a 9-pin or 24-
          pin dot-matrix printer, too.

          The files distributed with  SkyMap require a total of about 1.4MB
          of disk space.



























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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          Setting Up SkyMap
          Setting Up SkyMap
          Setting Up SkyMap

          Before SkyMap can be used, it must be installed on your computer,
          then configured to know about your location and time zone.


          Installing the Software
          Installing the Software
          Installing the Software

          SkyMap is distributed as three ZIP archive files - one containing
          the program and documentation; one containing the support files
          essential to the program's operation, and the third containing
          optional files which enhance the program but are not essential.

          The program archive, which will probably be called "SKYMP13A.ZIP"
          should contain the following files:

               README.1ST     Read this file!
               REGISTER.TXT   Registration information
               HISTORY.TXT    SkyMap release history
               SKYMAP.EXE     The SkyMap program
               SKYMAP.HLP     On-line help file
               SKYMAP.TXT     This manual
               CTL3D.DLL      3D control library
               MWSPIN.DLL     Spin button control library
               MSDNTB.DLL     ToolBar library

          The data and support archive, which will probably be called
          "SKYMP13B.ZIP", should contain the following files:

               README.2ND     Read this file!
               STAR.SKY       Main star database
               STARNAME.SKY   Star name database
               STARPROP.SKY   Star proper name database
               CONFIGUR.SKY   Constellation figures database
               CONNAME.SKY    Constellation name database
               MOON.SKY       Moon position database
               PLANETS.SKY    Planet position database

          The optional files archive, which will probably be called
          "SKYMP13C.ZIP", should contain the following files:

               README.3RD     Read this file!
               CONOUTLN.SKY   Constellation boundaries database
               RNGC.SKY       RNGC non-stellar object database
               RNGCPOP.SKY    RNGC object popular name database

          You may also have one or more picture file archives.  Please
          refer to the "Displaying Pictures" section of the manual for
          information about how to use these.

          To install SkyMap, carry out the following steps:





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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          1.  Create a directory on your hard disk.  For the purposes of
          this discussion we'll assume you want to install the program in
          directory SKYMAP on your C: drive.  Enter the commands:

               C:
               MD \SKYMAP

          2.  Unpack both the archive files into the directory.  Assuming
          that the archives are on a floppy disk in the A: drive you would
          do this with the commands:

               CD \SKYMAP
               PKUNZIP A:\SKYMP13A
               PKUNZIP A:\SKYMP13B
               PKUNZIP A:\SKYMP13C

          3.  Read the "Readme" text files.  They may contain important
          additions to the information in this manual!

          4.  Select the Program Manager group you'd like to add the SkyMap
          icon into.

          5.  From the Program Manager's "File" menu, select "New...".  A
          dialog box will appear.  Select "Program Item" (this should be
          the default, anyway) and press the OK button.

          6.  The "Program Item Properties" dialog will appear.  Fill it in
          as shown below, then press the <OK> button.

               Description:        SkyMap
               Command Line:       SKYMAP.EXE
               Working Directory:  C:\SKYMAP

          The SkyMap icon (a picture of a telescope) should appear in the
          Program Manager group window.  SkyMap is now installed and ready
          to run.


          Configuring SkyMap for your Location
          Configuring SkyMap for your Location
          Configuring SkyMap for your Location

          When SkyMap is run for the first time, you must configure it for
          the your location.  Before SkyMap can correctly draw a map of the
          sky for you, you have to tell it where you are, and what time
          zone you are in.  To configure the program, carry out the
          following steps:

          1.  Run SkyMap by double clicking on its icon in the Program
          Manager.  The empty SkyMap main window should appear.  Note the
          grey "status bar" at the bottom of the window.  This is used to
          display important information to the user, so keep an eye on it!

          2.  From the File menu, choose "New...".  The "Create New Window"
          dialog box will appear, which lists the different types of window
          you can create.  Press <Enter> to create a Horizon Map window,


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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          which will be the default.  A blank Horizon Map window will
          appear, and additional items will be added to the menu bar.  Note
          that the message "Press F5 to draw the map" has appeared on the
          status bar.  Ignore this message for the time being!

          3.  From the "Options" menu, choose "Observer...".  The
          "Observer" dialog box will be displayed.  This is where you set
          up all the information about the location you will be observing
          from.

          Fill in your longitude and latitude, each in degrees, minutes,
          and seconds.  You need not be exact - a position correct to the
          nearest degree is fine unless extreme accuracy is required.

          In the "Local Time" box enter your time zone, expressed in
          minutes ahead or behind Universal Time (UT), commonly called
          Greenwich Mean Time (GMT).  Eg, if your time zone is Eastern
          Standard Time, you are 5 hours behind UT, so you would enter
          "300" (5x60) into the text box, and click the button to change
          the display to read "minutes behind UT".

          If Daylight Saving Time (called "Summer Time" in the UK) is
          currently in operation, check the appropriate box.  If it is not
          currently in force, leave the box blank.  If the box is checked,
          your local time is taken to be an extra hour ahead of UT.

          4.  Finally, you should save the information you've entered.
          From the "File" menu, choose "Save Defaults...".  A box will
          appear asking you if you really want to save the information.
          Press the "Yes" button, or just press <Enter> to save the
          information.  All the current map settings will be saved in a
          configuration file called SKYMAP.INI and will be used as the
          default values for all horizon maps subsequently drawn.

          5.  Press the <F5> key.  A "Please wait" box will be displayed
          for a few seconds (depending on the speed of your computer),
          after which a map of the southern part of the sky as it currently
          looks from your location will appear in the map window.
          Congratulations - you have successfully drawn your first map!

          Note the following features of the map:

          1.  The "status bar" at the bottom of the window displays
          information about the map, such as the time and date, and the
          coordinates of the map centre.

          2.  The "Toolbar" at the top of the window provides a shortcut
          method of accessing many of the most frequently used commands, as
          well as giving an instant view of which map features are
          currently enabled.

          3.  Along the bottom of the map is the horizon, with the compass
          points displayed along it.  By default, the program displays a
          view of  roughly one third of the sky, centred on the southern


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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          horizon.  The zenith (the point directly overhead) is at the top
          of the map.

          4.  Stars are displayed as dots of differing sizes.  The brighter
          the star, the larger the dot.  By default, stars down to
          magnitude 5.0 are displayed, although the star database supplied
          with the program contains stars down to magnitude 7.0.  (The
          complete SAO catalog is reasonably complete down to about
          magnitude 9.5.)

          5.  By default, constellation names and figures are displayed.
          These can both be switched off using the items on the "View"
          menu, or by clicking on the appropriate buttons on the Toolbar.

          6.  Planets are shown as dots, with the standard astronomical
          symbol alongside.  The Moon is displayed with its correct phase
          and orientation.  The Sun is displayed as a hollow circle.







































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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          Horizon Maps
          Horizon Maps
          Horizon Maps

          A horizon map shows the sky as seen from the observer's location
          for a particular time and date.  It will probably be the starting
          point for most runs of SkyMap.


          Drawing a Horizon Map
          Drawing a Horizon Map
          Drawing a Horizon Map

          To draw a horizon map, the following steps should be followed:

          1.  From the "File" menu, choose "New...".  The "Create New
          Window" dialog box will be displayed, showing the different types
          of window that can be created.  "Horizon Map" should be the
          default selection in the list, so simply press <Enter> to create
          a new Horizon Map window.

          2.  Use the items on the "Options" menu to set all the options
          required for the map.  These options are described below.  Once
          the options have been set, you can save them to be used as the
          defaults for all future Horizon maps by selecting the "Save
          Defaults..." option from the "File" menu.

          3.  Use the items on the "View" menu to select which features you
          would like plotted on the map.  Most of these can also be
          selected from the Toolbar, too.

          4.  Press the <F5> key to draw the map.  This process will take
          anything from a few seconds to (in extreme cases!) several
          minutes, depending on the speed of your computer, and the
          complexity of the map.

          5.  When the map appears, you can zoom in or out on it, identify
          objects on it, or print it.  These options are described later.


          Horizon Map Options
          Horizon Map Options
          Horizon Map Options

          Viewpoint

          This option allows you to determine which part of the sky appear
          on the map.  When this option is selected, the "Horizon View"
          dialog is displayed.

          The "Azimuth" and "Altitude" fields specify the coordinates of
          the centre of the map.  The azimuth corresponds to the compass
          direction you are looking in and has the value 0. for due North,
          90. for East, 180. for South, and 270. for West.  The altitude
          indicates how far up you are looking, and is 0. on the horizon,
          and 90. directly overhead.

          The "Radius" field specifies the vertical size of the map.  The
          minimum altitude displayed on the map will be "Radius" degrees
          below the centre; the maximum altitude will be "Radius" degrees


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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          above the centre (ie, the range of altitude displayed on the map
          will be double the value entered).  The azimuth range of the map
          is scaled automatically.

          Notes:

          1.  Even if the radius is greater than the centre azimuth (ie,
          Centre-Radius<0), objects below the horizon will not be displayed
          - the horizon line will simply appear higher up the map.

          2.  To display a circular map of the whole sky, enter a centre
          altitude of 90., and a radius of 90..  In this case the azimuth
          setting simply determines the orientation of the map - the
          specified azimuth will be appear at the bottom of the map.

          Time

          The time and date for which the map is drawn are initially set
          from the computer's clock for the instant that the Horizon Map
          window is created.  The Time option allows the user to display a
          map for any other time and date.  When this option is selected,
          the "Observation Time" dialog is displayed.

          Fill in the dialog fields for the time and date required.
          Pressing the "Now" button will read the time and date from the
          computer's clock.

          Notes:

          1.  Dates before 1AD should be entered as negative numbers in the
          normal astronomical manner.  Enter the year 1BC as "0", 1000BC as
          "-999", and so on.

          2.  Dates must be between 4000BC (-3999) and 8000AD, this being
          the range over which the program's calculations are valid.

          3.  Dates on or after 0h on 15th October 1582 are assumed to be
          in the Gregorian calendar; dates before then in the Julian
          calendar.

          4.  The observation time is assumed to be a local time - ie, the
          time as shown on an observer's clock.  The time zone information
          specified on the Observation Location dialog (see below) is used
          to convert the time to UT.

          Observer

          The Observer option allows the user to enter information about
          the location from which the observation is taking place.  When
          this option is selected, the "Observer" dialog is displayed.

          The "Latitude" and "Longitude" fields specify the location of the
          observer.  Both are entered in degrees, minutes, and seconds



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          although, unless extreme accuracy is required, a position correct
          to the nearest degree will normally suffice.

          The "Conditions" information describes the atmospheric
          temperature and pressure at the time of observation.  This
          information is used when calculating the effects of refraction.
          Changing these values only has a very small effect and, unless
          extreme accuracy is desired, they may safely be left at their
          default values.

          The "Local Time" data specifies the observer's time zone.  It is
          used to convert the time of observation (which is always assumed
          to be local time) into UT or GMT.  The time difference is entered
          in minutes (not hours!) difference between local time and UT.
          For example, an observer on the east coast of the USA, whose
          clocks are set 5 hours earlier than GMT, should enter "300" (5 x
          60) in this box, and click the arrow to change the text to
          "before UT".

          The "Daylight saving time" box should be checked if DST (called
          "Summer Time" in the UK, and perhaps other countries too) is
          currently in operation.  If the box is checked, the local time is
          assumed to be one additional hour ahead of UT.

          Notes:

          1.  The reason that the time difference is entered in minutes,
          rather than hours, is that not all countries are exact hours
          ahead of or behind GMT.  India, for example, is 5.5 hours (330
          minutes) ahead of GMT.

          Stars

          The Stars option controls both which stars are plotted on the
          map, and the way that plotted stars are displayed.  When this
          option is selected, the "Star Display" dialog is displayed.

          The "Limiting magnitude of map" field determines the magnitude of
          the faintest star whose position will be calculated.  The higher
          the number, the fainter the stars which will be displayed (and
          the longer the map will take to compute).  The star database
          supplied with the program contains stars down to magnitude 7.0;
          the full SAO star catalog has stars down to magnitude 9.5 or so.

          The "Limiting magnitude displayed" field determines the magnitude
          of the faintest star that will actually be displayed on the map.
          Once a map has been drawn, you can change the value in this field
          to temporarily suppress the display of the fainter stars on a
          map, to remove "clutter".  The value entered in this field should
          be less than or equal to the value entered in the "Limiting
          magnitude" field above..

          The lower half of the dialog box controls the way that the size
          of the star images varies with their magnitude.  All stars


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          brighter than the first "Display mag" field will be displayed
          using the size of star circle shown to its right.  All stars
          fainter than the second "Display mag" field will be displayed
          using the size of star circle shown to its right.  All stars with
          magnitudes between these two limits will be drawn with an image
          size inversely proportional to the magnitude (ie, the brighter
          the star, the larger the image).

          Notes:

          1.  The number of stars rises very quickly with magnitude.
          Generally, increasing the limiting magnitude by one magnitude
          will more than double the number of stars visible on the map, and
          consequently the time taken to compute their positions.


          Star Labels

          This option controls the way in which stars are labelled on the
          map.  When selected, the "Star Labels" dialog box is displayed.

          The way in which stars are named has evolved over hundreds of
          years.  As a result, a lot of the brighter stars have many
          different names.  The "Label Preferences" box allows the user to
          determine which, if any, of those names is displayed on the map.

          "Proper Names" refers to the "popular" name of a star, such as
          "Polaris" or "Rigel".
          "Bayer Letters" refers to the convention of labelling the
          brightest stars in each constellation with Greek letters, such as
          "Alpha Centauri" or "Beta Cygni".
          "Flamsteed Numbers" refers to the convention of labelling stars
          in each constellation with numbers, such as "61 Cygni".

          The "Label Options" box at the bottom of the dialog box
          determines which stars are labelled.  If "All stars" is selected,
          then all stars which have the appropriate name will be labelled.
          If "Brighter than magnitude" is selected, then only those stars
          brighter than the number in the edit box will be labelled.

          Notes:

          1.  This dialog only determines the way in which stars are
          labelled.  If order to actually display star labels, the "Star
          Labels" option must be enabled on the "View" menu or the Toolbar.

          2.  If a star has multiple names, and more than one of the naming
          options is selected in the "Preferences" box, the name highest up
          the box will be displayed.  Eg, if both the "Proper Names" and
          "Bayer Letters" options are selected, the map would display the
          name "Polaris" in preference to "Alpha Ursae Minoris" when
          labelling the pole star.

          Labels


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          Selecting this option displays a submenu of labelling options.
          If the "Altitude" option is selected, the "Altitude Label
          Options" dialog box is displayed.

          The "Label type" radio buttons allow the type of altitude
          labelling to be selected.  The options are:

               Automatic The label interval is selected automatically.
               Every ... The label interval is specified in the text box.
               Nothing   No altitude labels are displayed.

          If the "Draw Altitude Lines" box is checked, altitude lines are
          drawn across the map at the appropriate (manual or automatic)
          intervals, and the lines are labelled at the left-hand side of
          the map.

          If the box is blank, altitude tick marks are drawn in the centre
          of the map.

          Notes:

          1.  If the "Nothing" box is selected, neither altitude lines nor
          labels are drawn, regardless of the state of the "Draw Altitude
          Lines" check box.


          Selecting the "Azimuth" option from the "Labels" submenu displays
          the "Azimuth Label Options" dialog box.

          The radio buttons in the "Label with" box control the type of
          azimuth labelling, and determine which (if any) of the other
          values in the dialog are used.

          If the "Compass Points" button is selected, the horizon is
          labelled with the names of compass points, and the options in the
          "Compass Interval" section of the dialog are used.

          If the "Azimuth" button is selected, the horizon is labelled with
          azimuth numbers (in degrees), and the options in the "Azimuth
          Interval" section of the dialog are used.

          If the "Nothing" button is selected, the azimuth axis is not
          labelled, and the rest of the dialog is ignored.

          The "Compass Interval" section of the dialog determines the
          labelling method used when "Compass Point" labelling is selected.
          The radio buttons allow the labelling interval to either be
          determined automatically, or one of three manual intervals
          selected.

          The "Azimuth Interval" section of the dialog determines the
          labelling method used when "Azimuth" labelling is selected.  The
          options allow the labelling interval to be either determined


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          automatically, or specified manually by the value in the text
          field.

          If the "Draw Azimuth Lines" box is checked, lines are drawn up
          from the labelled points on the horizon to the top of the map.

          Notes:

          1.  Azimuth lines are always labelled on the horizon line.  If
          the horizon line is not visible on the map, you will not see any
          labels!


          Constellation Names

          This option allows the user to choose the font used for
          constellation names.  Selecting this option displays a standard
          font selection dialog.


          RNGC Objects

          Selecting this option displays the "RNGC Options" dialog box,
          allowing you to determine which deep sky objects are displayed on
          the map.

          The "Object Selection" box determines which catalogue will be
          searched to find objects to display; the entire RNGC catalogue or
          only Messier objects.

          The "Object Types" box controls which objects will be displayed
          on the map, based on their type.  If the "All objects" box is
          checked, then the other boxes in the group are ignored, and all
          objects which match the other selection criteria will be
          displayed.  If the "All objects" box is not checked, individual
          types of object can be selected using the other boxes in this
          group.

          The "Magnitude Limit" box allows you to control which objects are
          displayed, based on a magnitude selection.  If "All Objects" is
          selected, then all objects matching the other selection
          parameters will be displayed; if "Brighter than mag" is selected,
          then only those objects brighter than the specified magnitude
          will be displayed.

          Finally, the "Label Objects" box, determines whether displayed
          objects will be labelled.  If the box is checked, objects will be
          labelled.  Messier objects will be labelled "M" followed by a
          number (eg "M32"); other objects will simply have their RNGC
          catalogue number displayed (eg "1985" refers to the planetary
          nebula "RNGC 1985" ).

          Notes:



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          1.  This is a complex dialog box - the most complex in the
          program! - but it gives you the ability to exercise very fine
          control over the non-stellar objects which are displayed.  For
          example, you can make selections such as "only display globular
          clusters in the Messier catalogue brighter than magnitude 11".

          2.  The program will only display those Messier objects that are
          in the RNGC.  Four objects in the Messier catalogue are not in
          the RNGC, so will not be drawn.  These are: M24 (a local
          brightening of the Milky Way), M25 (the open cluster IC 4725),
          M40 (the wide double star Winneke 4), and M45 (the Pleiades).

          3.  The RNGC is based on the NGC, compiled towards the end of the
          19th century.  As such, it contains many incorrect
          classifications, based on the information available at the time.
          For example, the Crab Nebula in Taurus, M1, we now know to be a
          supernova remnant, but the RNGC classifies it as a planetary
          nebula.  The RNGC is, however, a catalogue of great historical
          significance, and no attempt has been made by the author to
          "correct" it.

          4.  The symbols used to draw non-stellar objects on the map have
          been based on those used in the authoritative "Uranometria 2000"
          star atlas.


          Colours

          This option displays a sub-menu allowing the user to select the
          colours used for every item drawn on the map for either the
          screen or the printer.  When either "Screen" or "Printer" is
          selected, the "Horizon Map Colours" dialog box is displayed.

          To view or edit the colour of any map component, either double
          click on the name in the listbox, or move the listbox highlight
          to the name and press the "Edit..." button.  Either way, a
          standard colour selector box will be displayed, letting you
          choose the colour for the item.

          Notes:

          1.  Pressing the "Cancel" button will restore ___
                                                        all the colours to

          their previous settings, not only the colour just edited.

          2.  The "Printer" colour settings only relate to the printing of
          colour maps.  Refer to the printing section of the manual for
          further information.


          Reduce Positions

          This item is a "toggle switch", controlling whether position
          reductions are applied to objects displayed on the horizon map.


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          If this option is ticked, the positions of all objects are
          rigorously corrected for the effects of precession, nutation,
          aberration, parallax, and refraction.  If this option is not
          ticked, only the corrections for refraction and (for planets)
          diurnal parallax are applied.

          The purpose of this toggle is to speed up map display, especially
          on slow computers.  Unless very high accuracy is required, this
          option can safely be switched off for maps drawn for the time
          period 1950 - 2050.  Outside this period, the effects of
          precession start to become significant, and the option should
          always be switched on.

          Draw

          Selecting this option will draw the map, using the current option
          settings.  You may press the <F5> function key as a "shortcut"
          for this option.



          Using the Horizon Map
          Using the Horizon Map
          Using the Horizon Map

          Once the horizon map has been created using the methods described
          in the previous section of the manual, it can be manipulated in
          various way.  This section describes the available options:


          Setting the Visibility of Objects

          The first section of the "View" menu contains a list of item
          names, each of which has a tick alongside if that type of item is
          currently visible.  The items are:

               Stars
               Star Labels
               Planets
               Constellation Figures
               Constellation Boundaries
               Constellation Names
               Alt/Az Grid
               RNGC Objects

          Each of these items has a corresponding button on the ToolBar.
          To change an item from visible to invisible, or vice versa,
          either select the item from the menu, or press the button on the
          ToolBar.

          Changing the map scale

          The "Zoom In" and "Zoom Out" items on the "View" menu may be used
          to change the magnification of the map.  The <F2> and <F3>
          function keys are shortcuts for these operations, as are the
          first two buttons on the ToolBar.  When the map is first drawn,


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          it is scaled so that the map exactly fills a maximised map
          window.  Every time "Zoom In" is selected, the size of the map
          increases by 50%, and the map is redrawn.  Every time "Zoom Out"
          is selected, the size is correspondingly reduced.

          When the map is zoomed, the centre of the current window will
          remain stationary.  You can therefore zoom in a particular
          feature by first scrolling it to the centre of the window, then
          repeatedly pressing the <F2> key.  To aid this process, a
          shortcut method has been provided to bring a point to the centre:

          1.  Position the mouse pointer over the point on the map you
          would like to bring to the centre.

          2.  Press the right mouse button.  A pop-up menu will appear
          under the mouse pointer.

          3.  Select the "Centre" item with the left mouse button.  The
          window will scroll to bring the chosen point to the centre of the
          map.

          Note that the map will not scroll past its edges (the boundaries
          of the full-screen normal size map).  In order to bring a point
          to the centre of the map it may, therefore, be necessary to zoom
          in one or more times first.


          Identifying Objects on the Map

          To display information about any object visible on the map, move
          the mouse pointer over the object, and press the right mouse
          button.  A pop-up menu will appear.  Select the item you wish to
          identify.  A dialog box will appear displaying information about
          the object.

          Stars:

          If you ask for information about a star, a "Star Information"
          dialog box is displayed.  The amount of information displayed
          will depend on the star, but will include the following:

          1.  The star's SAO catalogue number is displayed in the dialog
          box title.  The SAO number is the way that SkyMap identifies the
          star internally - all other information is derived from this.

          2.  The top section of the dialog displays the identify of the
          star.  The same star can be identified in a truly bewildering
          variety of different ways.  SkyMap attempts to show a few of the
          more popular names for the star:

          The first line of the dialog always displays the name of the
          constellation that the star is in.  In the case of a star which
          has either a Bayer letter or Flamsteed number, the star's
          constellation is actually stored in the database.  In cases where


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          this information is not present, the constellation is computed
          from the star's position, using the official IAU constellation
          boundaries.

          The next line, if present, displays the "proper name" of the star
          - "Rigel", for example.  Note that many star names are derived
          from Arabic and, as such, have a number of alternate English
          spellings.  In the case of such stars, the name that SkyMap
          displays may well be slightly different from the name your
          reference sources show.  All that means is that I used a
          different reference book!

          Next are shown the star's Bayer letter (eg beta Orionis) and
          Flamsteed number (19 Orionis), if present.

          Finally in the initial section of the dialog, the star's visual
          magnitude is shown.

          3.  The lower section of the dialog shows the position of the
          star in several different coordinate systems.

          First, the star's apparent geocentric right ascension and
          declination are displayed.  These coordinates are referred to the
          true equinox and ecliptic of date, and are corrected for:

               Proper Motion
               Annual Aberration
               Precession
               Nutation

          The star's position is also corrected for refraction before being
          displayed on the map, but the apparent position displayed in the
          dialog box does not include this correction.  Note that rigorous
          position corrections are applied,  regardless of the current
          setting of the "Reduce Positions" switch on the "Options" menu.

          Next, the star's catalogue position is displayed - the right
          ascension (RA) and declination for the mean equinox and ecliptic
          of epoch J2000.0.  This information is taken straight from the
          SAO star catalogue and contains no position corrections.

          Finally, the current altitude and azimuth as seen from the
          observer's location are displayed.  The altitude displayed here
          includes the effects of refraction.

          Planets:

          If information about a planet is requested, a more complex dialog
          with multiple screens of information is displayed.  The dialog
          has buttons down the right hand side for switching between the
          different screens of information.  The names on the buttons refer
          to the position of the viewer - eg, the "Sun" button displays a
          screen of heliocentric information.



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          The information displayed is as follows:

          The "Local" screen displays information about the planet as seen
          from the observer's location at the time and date for which the
          map is displayed.  The following information is displayed:

          1.  The altitude and azimuth of the planet as seen from the
          observer's location at the current time.  This is derived from
          the apparent geocentric position, with additional corrections
          being applied for diurnal parallax (the difference between the
          position of the planet as seen from the centre of the Earth and
          the position as seen from the observer's actual position) and
          refraction.


          The "Earth" screen (initially displayed) displays information
          about the planet as seen from the centre of the earth - ie,
          geocentric information.  The following information is displayed:

          1.  The apparent geocentric right ascension and declination,
          referred to the true equinox and ecliptic of date.  This position
          is corrected for the effects of:

               Light Time
               Light Deflection (due to the Sun's gravity)
               Annual Aberration
               Nutation

          The position of the planet as displayed on the map has additional
          corrections for diurnal parallax and refraction, but these
          corrections are not reflected in the position displayed here.

          2.  The constellation the planet is in.

          3.  The true (geometric) distance of the planet in both
          astronomical units (exactly) and millions of km (approximately).
          In the case of the Moon, the exact distance is displayed in km.


          The "Sun" screen displays information about the planet as seen
          from the centre of the Sun - ie, heliocentric data.  The
          following information is displayed:

          1.  The apparent ecliptic longitude and latitude of the planet,
          referred to the true ecliptic of date.

          2.  The geometric radius vector of the planet (ie, the distance
          between the planet and the Sun) in both astronomical units
          (exactly) and millions of km (approximately).


          The "Physical" screen displays physical information about the
          planet.  The following information is displayed:



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          1.  The visual magnitude.

          2.  The phase, as a fraction between 0 and 1.  A phase of 0
          indicates that the object is "new"; a phase of 1 is "full".  The
          phase is equal to the fraction of the planet's disk that is
          illuminated, as seen from the Earth.

          3.  The apparent diameter, in seconds of arc.  For some planets,
          separate equatorial and polar diameters are shown.

          4.  The phase angle, in degrees.  This is the angle between the
          Earth and Sun, as seen from the centre of the planet, and
          determines the phase of the planet as seen from the Earth.

          5.  The elongation, in degrees.  This is the angle between the
          planet and the Sun, as seen from the centre of the Earth.

          6.  The light time in hours, minutes, and seconds.  This is the
          time taken for light to travel from the planet to the observer,
          and is an indication of the "age" of the view we see of the
          planet.  Eg, if the light travel time for Mars is shown as 5
          minutes, this means that we are seeing Mars as it actually was 5
          minutes ago.

          RNGC Objects:

          If you ask for information about an RNGC object, a dialog box is
          displayed.  The amount of information displayed will depend on
          the object, but will include the following:

          1.  The dialog box title will contain the catalogue number of the
          object.  This will be shown as a Messier number for objects in
          the Messier catalogue, and an RNGC catalogue number otherwise.

          2.  The upper section of the dialog identifies and describes the
          object.  The following information could be displayed:

          RNGC Number:  For Messier objects, the corresponding number in
          the RNGC catalogue.  For example, in the case of "M44", this line
          will display "NGC 2632".

          Popular name:  Some objects have a "popular name" by which they
          are commonly known, in addition to their various catalogue
          numbers.  For example, in the case of M44, this line will display
          the name "Praesepe".

          Type of object:  A brief description of the object type, such as
          "Galaxy", "Globular Cluster", "Diffuse Nebula", etc.  As has
          already been stated, these classifications are not always
          correct, and should not be taken as an authoritative guide to
          what an object really is!  That having been said, the
          classification is correct for the vast majority of objects.




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          Magnitude:  The visual magnitude of the object.  It should be
          noted that this is normally an "integrated magnitude" - the total
          amount of light received from the whole of the object.  Normally,
          a 10th magnitude galaxy is visually a lot fainter than a 10th
          magnitude star, because in the case of the galaxy the light is
          coming from an area of sky, rather than from a point source.

          Description:  The "Dreyer Description" of the object.  When
          Dreyer compiled the NGC in 1888, he gave a brief visual
          description of the object in a highly compressed format.  These
          descriptions are, in the author's opinion, the real value of the
          NGC, since they indicate what you are likely to actually see in a
          typical modern amateur telescope.  The "encoded" format of the
          descriptions may seem cryptic and hard to understand at first
          but, with practice, soon becomes a useful source of information.
          Refer to Appendix B of the manual for a description of Dreyer
          descriptions.

          3.  The lower section of the dialog shows the position of the
          object in several different coordinate systems.

          The first line displays the name of the constellation the object
          is in.

          The second line shows the object's apparent geocentric right
          ascension and declination, referred to the true equinox and
          ecliptic of date.  The position is corrected for:

               Annual Aberration
               Precession
               Nutation

          The object's position is also corrected for refraction before
          being displayed on the map, but the apparent position displayed
          in the dialog box does not include this correction.  Note that
          rigorous position corrections are applied,  regardless of the
          current setting of the "Reduce Positions" switch on the "Options"
          menu.

          Next, the object's catalogue position is displayed - the right
          ascension (RA) and declination for the mean equinox and ecliptic
          of epoch J2000.0.  This information is taken straight from the
          RNGC catalogue and contains no position corrections.

          Finally, the current altitude and azimuth as seen from the
          observer's location are displayed.  The altitude displayed here
          includes the effects of refraction.


          Zooming to an Area Map

          If you wish to display a detailed "Area Map" of a particular
          region of the sky, position the mouse pointer over the point on
          the horizon map that you wish to be the centre of the area map.


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          Press the right mouse button and select "Area Map..." from the
          pop-up menu.  The "Sky Area View" dialog box will appear, with
          the coordinates of the map centre already filled in.  Enter the
          radius of the map you would like, in degrees, then press <Enter>.
          A blank area map window will appear.  The next chapter of the
          manual describes how to draw and use the Sky Area map.


          Printing the Map

          To print the map, choose the "Print" option from the "File" menu.
          This will display the "Print Options" dialog box.

          The "View Options" box selects what type of map is drawn.  If
          "Whole Map" is selected, the entire map will be drawn, scaled to
          fit onto the printer page.  If "Current View" is selected, the
          current map view will be printed, at the current zoom factor.

          The "Colour Options" box is used to select whether the map is
          printed in black and white or colour.  If "black and white" is
          selected, all objects on the map are printed black, and the map
          background is left white.  If "Colour" is selected, the map
          background is again left white, but the colour of all other
          objects is taken from the settings in the
          "Options/Colour/Printer" dialog.

          When the <OK> button is pressed, a standard "Print" dialog is
          displayed.  This allows you to select the printer, resolution,
          paper orientation etc in the normal way.  Press <OK> from this
          dialog to print the map.

          Notes:

          1.  By default, the map is printed in landscape orientation.  If
          you wish to change this, use the "Print Setup" option.

          2.  The default "Print Options" settings of "Whole Map" and
          "Black and White" correspond to the way that maps were printed in
          previous versions of SkyMap.

          3.  The "Current View" printout is intended as a "quick and
          dirty" method of getting a printed map of a zoomed-in area of the
          sky, without having to draw a separate Sky Area map and print
          that.  No attempt is made to properly scale the map to fit the
          paper size, draw borders, or anything else.  If you have a very
          high zoom factor set, and try to print to a high-resolution
          device using this settings, problems may occur.

          4.  The "Colour" setting in the "Colour Options" box can be used
          to print a grey-scale map even on a black and white printer.  The
          exact correspondence between colours and shades of grey will
          depend on the capabilities of the printer driver.  This works
          beautifully on a PostScript laser printer; not so well on an
          Epson 9-pin dot matrix printer!


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          Sky Area Maps
          Sky Area Maps
          Sky Area Maps

          A Sky Area map shows a detailed view of a (normally) small area
          of the sky, centred on a particular point of right ascension and
          declination.  It is a circular map, displaying all objects within
          a specified radius of the centre.


          Drawing a Sky Area Map
          Drawing a Sky Area Map
          Drawing a Sky Area Map

          There are two ways to draw a Sky Area map:

          1.  Draw a horizon map, then click the right mouse button over
          the location you want to be the centre of the Sky Area map.
          Select "Area Map..." from the pop-up menu which appears.

          2.  From the "File" menu, select "New...".  The "Create New
          Window" dialog box will appear.  Select "Sky Area Map" from the
          listbox and press <OK>.

          Whichever of these two methods is used, the "Sky Area View"
          dialog box will be displayed.

          The "Vertical Radius" field specifies the radius of the map, in
          degrees.  This must be between 1. and 90..  The "Right Ascension"
          and "Declination" fields specify the coordinates of the map
          centre.  If you are drawing the Area map from a Horizon map,
          these will already contain the correct values.

          When the dialog is correctly filled in, press <OK> to create a
          new map.  A blank Sky Area Map window will be displayed, and the
          menu will change to the Sky Area menu.

          Use the items on the "Options" menu to set all the options
          required for the map.  These options are described below.  Once
          the options have been set, you can save them to be used as the
          defaults for all future Sky Area maps by selecting the "Save
          Defaults..." option from the "File" menu.

          Finally, press the <F5> key to draw the map.  This process will
          take anything from a few seconds to (in extreme cases!) several
          minutes, depending on the speed of your computer, and the
          complexity of the map.



          Sky Area Map Options
          Sky Area Map Options
          Sky Area Map Options

          Viewpoint

          This option allows the user to specify which part of the sky is
          visible on the map.  When this option is selected, the "Sky Area
          View" dialog is displayed.



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          The "Vertical Radius" field controls the radius of the map.  It
          can take values ranging from 1o to 90o.  The total field of view
          of the map will be double the value entered here.

          The "Right Ascension" and "Declination fields specify the
          coordinates of the centre of the map.  Right Ascension is entered
          in hours and minutes of time; declination in degrees and minutes
          of arc.


          Time

          The time and date for which the map is drawn are initially set
          from the computer's clock for the instant that the Sky Area Map
          window is created.  The Time option allows the user to display a
          map for any other time and date.  When this option is selected,
          the "Observation Time" dialog is displayed.

          Fill in the dialog fields for the time and date required.
          Pressing the "Now" button will read the time and date from the
          computer's clock.

          Notes:

          1.  Although the map is drawn centred on a fixed point on the
          RA/Dec coordinate grid, the date and time are still used to
          calculate such things as planetary positions, and also, over long
          periods of time, affect which stars are visible on the map, due
          to the effects of proper motion and precession.

          2.  Dates before 1AD should be entered as negative numbers in the
          normal astronomical manner.  Enter the year 1BC as "0", 1000BC as
          "-999", and so on.

          3.  Dates must be between 4000BC (-3999) and 8000AD, this being
          the range over which the program's calculations are valid.

          4.  Dates on or after 0h on 15th October 1582 are assumed to be
          in the Gregorian calendar; dates before then in the Julian
          calendar.

          5.  The observation time is assumed to be a local time - ie, the
          time as shown on an observer's clock.  The time zone information
          specified on the Observation Location dialog (see below) is used
          to convert the time to UT.


          Observer

          The Observer option allows the user to enter information about
          the location from which the observation is taking place.  When
          this option is selected, the "Observer" dialog is displayed.




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          The "Latitude" and "Longitude" fields specify the location of the
          observer.  Both are entered in degrees, minutes, and seconds
          although, unless extreme accuracy is required, a position correct
          to the nearest degree will normally suffice.

          The "Conditions" information describes the atmospheric
          temperature and pressure at the time of observation.  This
          information is used to calculate the effects of refraction, so
          has no influence on the Sky Area map.

          The "Local Time" data specifies the observer's time zone.  It is
          used to convert the time of observation (which is always assumed
          to be local time) into UT or GMT.  The time difference is entered
          in minutes (not hours!) difference between local time and UT.
          For example, an observer on the east coast of the USA, whose
          clocks are set 5 hours earlier than GMT, should enter "300" (5 x
          60) in this box, and click the arrow to change the text to
          "before UT".

          The "Daylight saving time" box should be checked if DST (called
          "Summer Time" in the UK, and perhaps other countries too) is
          currently in operation.  If the box is checked, the local time is
          assumed to be one additional hour ahead of UT.

          Notes:

          1.  The reason that the time difference is entered in minutes,
          rather than hours, is that not all countries are exact hours
          ahead of or behind GMT.  India, for example, is 5.5 hours (330
          minutes) ahead of GMT.

          2.  The location of the observer is used by the Sky Area map when
          calculating the effects of "diurnal parallax" for nearby objects
          such as the Sun, Moon, and planets.  This is the difference in
          the apparent position of a nearby body against the star
          background as seen from different places on Earth.  In the case
          of the Moon in particular, the correction for diurnal parallax is
          important, and can alter the Moon's apparent place by up to 2o -
          four times the Moon's apparent diameter!


          Stars

          The Stars option controls which stars are plotted on the map, and
          also the way that plotted stars are displayed.  When this option
          is selected, the "Star Display" dialog is displayed.

          The "Limiting magnitude of map" field determines the magnitude of
          the faintest star whose position will be calculated.  The higher
          the number, the fainter the stars which will be displayed (and
          the longer the map will take to compute).  The star database
          supplied with the program contains stars down to magnitude 7.0;
          the full SAO star catalog has stars down to magnitude 9.5 or so.



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          The "Limiting magnitude displayed" field determines the magnitude
          of the faintest star that will actually be displayed on the map.
          Once a map has been drawn, you can change the value in this field
          to temporarily suppress the display of the fainter stars on a
          map, to remove "clutter".  The value entered in this field should
          be less than or equal to the value entered in the "Limiting
          magnitude" field above..

          The lower half of the dialog box controls the way that the size
          of the star images varies with their magnitude.  All stars
          brighter than the first "Display mag" field will be displayed
          using the size of star circle shown to its right.  All stars
          fainter than the second "Display mag" field will be displayed
          using the size of star circle shown to its right.  All stars with
          magnitudes between these two limits will be drawn with an image
          size inversely proportional to the magnitude (ie, the brighter
          the star, the larger the image).

          Notes:

          1.  The number of stars rises very quickly with magnitude.
          Generally, increasing the limiting magnitude by one magnitude
          will more than double the number of stars visible on the map, and
          consequently the time taken to compute their positions.


          Stars Labels

          This option controls the way in which stars are labelled on the
          map.  When selected, the "Star Labels" dialog box is displayed.

          The way in which stars are named has evolved over hundreds of
          years.  As a result, a lot of the brighter stars have many
          different names.  The "Label Preferences" box allows the user to
          determine which, if any, of those names is displayed on the map.

          "Proper Names" refers to the "popular" name of a star, such as
          "Polaris" or "Rigel".
          "Bayer Letters" refers to the convention of labelling the
          brightest stars in each constellation with Greek letters, such as
          "Alpha Centauri" or "Beta Cygni".
          "Flamsteed Numbers" refers to the convention of labelling stars
          in each constellation with numbers, such as "61 Cygni".

          The "Label Options" box at the bottom of the dialog box
          determines which stars are labelled.  If "All stars" is selected,
          then all stars which have the appropriate name will be labelled.
          If "Brighter than magnitude" is selected, then only those stars
          brighter than the number in the edit box will be labelled.

          Notes:





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          1.  This dialog only determines the way in which stars are
          labelled.  If order to actually display star labels, the "Star
          Labels" option must be enabled on the "View" menu or the ToolBar.

          2.  If a star has multiple names, and more than one of the naming
          options is selected in the "Preferences" box, the name highest up
          the box will be displayed.  Eg, if both the "Proper Names" and
          "Bayer Letters" options are selected, the map would display the
          name "Polaris" in preference to "Alpha Ursae Minoris" when
          labelling the pole star.


          Constellation Names

          This option displays a standard font selector allowing the user
          to select the font used to write constellation names on the map.


          RNGC Objects

          Selecting this option displays the "RNGC Options" dialog box,
          allowing you to determine which deep sky objects are displayed on
          the map.

          The "Object Selection" box determines which catalogue will be
          searched to find objects to display; the entire RNGC catalogue or
          only Messier objects.

          The "Object Types" box controls which objects will be displayed
          on the map, based on their type.  If the "All objects" box is
          checked, then the other boxes in the group are ignored, and all
          objects which match the other selection criteria will be
          displayed.  If the "All objects" box is not checked, individual
          types of object can be selected using the other boxes in this
          group.

          The "Magnitude Limit" box allows you to control which objects are
          displayed, based on a magnitude selection.  If "All Objects" is
          selected, then all objects matching the other selection
          parameters will be displayed; if "Brighter than mag" is selected,
          then only those objects brighter than the specified magnitude
          will be displayed.

          Finally, the "Label Objects" box, determines whether displayed
          objects will be labelled.  If the box is checked, objects will be
          labelled.  Messier objects will be labelled "M" followed by a
          number (eg "M32"); other objects will simply have their RNGC
          catalogue number displayed (eg "1985" refers to the planetary
          nebula "RNGC 1985" ).

          Notes:

          1.  This is a complex dialog box - the most complex in the
          program! - but it gives you the ability to exercise very fine


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          control over the non-stellar objects which are displayed.  For
          example, you can make selections such as "only display globular
          clusters in the Messier catalogue brighter than magnitude 11".

          2.  The program will only display those Messier objects that are
          in the RNGC.  Four objects in the Messier catalogue are not in
          the RNGC, so will not be drawn.  These are: M24 (a local
          brightening of the Milky Way), M25 (the open cluster IC 4725),
          M40 (the wide double star Winneke 4), and M45 (the Pleiades).

          3.  The RNGC is based on the NGC, compiled towards the end of the
          19th century.  As such, it contains many incorrect
          classifications, based on the information available at the time.
          For example, the Crab Nebula in Taurus, M1, we now know to be a
          supernova remnant, but the RNGC classifies it as a planetary
          nebula.  The RNGC is, however, a catalogue of great historical
          significance, and no attempt has been made by the author to
          "correct" it.

          4.  The symbols used to draw non-stellar objects on the map have
          been based on those used in the authoritative "Uranometria 2000"
          star atlas.


          Colours

          This option displays a sub-menu allowing the user to select the
          colours used for every item drawn on the map for either the
          screen or the printer.  When either "Screen" or "Printer" is
          selected, the "Horizon Map Colours" dialog box is displayed.

          To view or edit the colour of any map component, either double
          click on the name in the listbox, or move the listbox highlight
          to the name and press the "Edit..." button.  Either way, a
          standard colour selector box will be displayed, letting you
          choose the colour for the item.

          Notes:

          1.  Pressing the "Cancel" button will restore ___
                                                        all the colours to

          their previous settings, not only the colour just edited.

          2.  The "Printer" colour settings only relate to the printing of
          colour maps.  Refer to the printing section of the manual for
          further information.


          Draw

          Selecting this option will draw the map, using the current option
          settings.  You may press the <F5> function key as a "shortcut"
          for this option.



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          Using the Sky Area Map
          Using the Sky Area Map
          Using the Sky Area Map

          Once the Sky Area map has been drawn, it can be manipulated in
          various ways.  Most of the options are the same as for the
          Horizon Map, so they are just summarised here for ease of
          reference.


          Setting the Visibility of Objects

          The top section of the "View" menu consists of a list of
          "toggles" controlling the visibility of various items on the Area
          map.  Each item has a corresponding button on the ToolBar.  If an
          item has a tick mark alongside it on the menu, or its button is
          in a "pressed" state on the ToolBar, it is currently visible on
          the map.  If it does not have a tick mark, or its button is not
          pressed, it is not visible.  The items are:

               Stars
               Star Labels
               Planets
               Constellation Figures
               Constellation Boundaries
               Constellation Names
               Right ascension/Declination Grid
               RNGC Objects


          Changing the map scale

          The "Zoom In" and "Zoom Out" items on the "View" menu may be used
          to change the magnification of the map.  The <F2> and <F3>
          function keys are shortcuts for these operations, as are the
          first two buttons on the ToolBar.  These options operate exactly
          as they do for the Horizon map.


          Identifying Objects on the Map

          To display information about any object visible on the map, move
          the mouse pointer over the object, and press the right mouse
          button.  A pop-up menu will appear.  Select the item you wish to
          identify.  A dialog box will appear displaying information about
          the object.


          Zooming to an Area Map

          To display a new Area map centred on a particular point on the
          current map, position the mouse pointer over the required point
          and press the right mouse button.  Select "Area Map..." from the
          pop-up menu.


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          Printing the Map

          To print the map, choose the "Print" option from the "File" menu.
          The options displayed are exactly the same as for the Horizon
          Map.

















































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          Displaying Pictures
          Displaying Pictures
          Displaying Pictures

          One of the most exciting features of SkyMap is its ability to
          display photographic images of astronomical objects.  You can
          build up your own collection of pictures which, together with the
          maps, can really bring the sky to "life", and which are a superb
          way to show astronomical objects to a novice on a cloudy night!
          (Here in England we get a lot of cloudy nights!)

          In order to display pictures, you really need a "SuperVGA"
          display capable of displaying 256 or more colours at once.  You
          can display pictures on a standard 16-colour VGA display, but the
          results will probably be pretty horrible!


          Picture Formats
          Picture Formats
          Picture Formats

          SkyMap can currently display picture files in the following
          formats:

          1.  GIF files.  GIF is probably the most popular of all image
          formats currently in use.  The format was specifically devised to
          enable pictures to be easily transferred between different types
          of computer, and there are literally tens of thousands on
          pictures in GIF format available.  SkyMap will display files in
          either GIF87a or GIF89a format, and can handle both interlaced
          and non-interlaced images.  The only restriction is that only the
          first image in a file can currently be displayed.  GIF files for
          the PC normally have an extension of ".GIF".

          2.  Windows "Bitmap" files.  These are "device independent
          bitmap" files created for use with Microsoft Windows.  They
          normally have an extension of ".BMP" (for uncompressed images) or
          ".RLE" (for compressed images).  An increasing number of these
          files can be found on bulletin board systems, normally made
          available for use as Windows "wallpaper".


          Displaying Pictures Manually
          Displaying Pictures Manually
          Displaying Pictures Manually

          From the "File" menu, choose the "Open Image..." item.  A
          standard file selector will be displayed, letting you select a
          file from any available drive or directory.  Pressing the <OK>
          button will create a new window in which the image will be
          displayed.


          Displaying Pictures Automatically
          Displaying Pictures Automatically
          Displaying Pictures Automatically

          SkyMap has the ability to load and display pictures of certain
          object automatically.  This can be done for all RNGC objects, as
          well as the planets, Moon, and Sun.  In order to use this feature
          of the program, carry out the following steps:



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          1.  Find a nice picture of an RNGC object or planet in any
          supported image format.  You can use the "manual" method
          described above to look through pictures until you find one you
          would like to have as a "standard" picture for a particular
          object.

          2.  Copy the picture to the directory containing the SkyMap
          program, and rename the file to "OBJECT.EXT", where "OBJECT" is
          the name of the object, and ".EXT" is the "standard" extension
          for the image format - ".GIF" for GIF files and ".BMP" for bitmap
          files.

          For planets, the name used should be one of the following:

               SUN
               MOON
               MERCURY
               VENUS
               MARS
               JUPITER
               SATURN
               URANUS
               NEPTUNE

          For Messier objects, the name should be "M" followed by the
          Messier number; "M32", for example.

          For other RNGC objects, the name should be "NGC" followed by the
          RNGC catalogue number; "NGC1530A", for example.

          3.  Now, if you draw a map and click the right mouse button over
          an object for which a picture has been stored, you should find
          that a "Picture of <object>" item appears on the resulting pop-up
          menu.  Selecting this item will display the picture in a new
          window.

          Notes:

          1.  When you click on a object, SkyMap will first of all look for
          a file with a ".GIF" extension, and then for a file with a ".BMP"
          extension.  If files with both extensions are present, the GIF
          file will be displayed.


          Obtaining Picture Files
          Obtaining Picture Files
          Obtaining Picture Files

          There are many sources from which picture files (particularly GIF
          images) suitable for use with SkyMap can be obtained.  Some of
          these are:

          1.  Commercial information services such as CompuServe or BIX.
          An especially good source is the CompuServe "Astronomy" forum
          (type "GO ASTROFORUM" from any prompt), which currently has more
          than 1000 astronomy and space-related GIF files available.


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          2.  Bulletin board systems, of which there are a vast and ever-
          changing number.  Some of these specialise in astronomy and carry
          a large number of GIF images.

          3.  Public domain and shareware software libraries.

          4.  If you have access to it, perhaps the best source of all are
          the ____
              vast resources of the Internet - a world-wide computer

          network.  Take a look, for example at the machine
          "ames.arc.nasa.gov", in directory "pub/SPACE/GIFS".

          5.  Finally, if you get really stuck, I can supply you with GIF
          images for the cost of the disks plus a small handling fee.
          Refer to the separate registration form for details.








































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          Appendix A:  Data Sources and Precision
          Appendix A:  Data Sources and Precision
          Appendix A:  Data Sources and Precision

          The sources of the data used by SkyMap are as follows:


          Stars
          Stars
          Stars

          Smithsonian Astrophysical Observatory (SAO) star catalog,  (SAO
          Staff, 1966), 1990 machine readable version, as supplied on
          NASA's National Space Science Data Center's "Selected
          Astronomical Catalogs, Volume 1" CD-ROM.

          The SAO star catalog is a catalog of 258,997 stars to epoch
          J2000.0, and is reasonably complete down to magnitude 9.5 or so.
          The star database supplied with the shareware version of SkyMap
          contains all the stars from the SAO catalog down to magnitude 7.0
          - a total of 15,931 stars.  Larger databases, up to and including
          the full SAO catalog,  can be supplied to registered users of
          SkyMap for a small  fee - refer to the separate registration form
          for details.

          SkyMap rigorously reduces star positions from mean to apparent
          place.  The following corrections are applied:

               Precession
               Proper Motion
               Nutation
               Aberration

          In the case of the Horizon Map, the apparent place is used to
          compute the local altitude and azimuth of the star, and the
          altitude is then corrected for the effects of refraction.


          Planets and Sun
          Planets and Sun
          Planets and Sun

          The positions of the Sun, and the planets Mercury to Neptune are
          computed using a subset of  Bretagnon and Francou's VSOP87
          planetary theory, as described in the book "Astronomical
          Algorithms", by Jean Meeus (Willman-Bell, 1991).

          Spot checks against recent editions of the "Astronomical Almanac"
          indicate that the mean error in the computed positions of the
          planets is under half a second of arc, with peak errors of about
          one arc second.  For comparison, the apparent diameter of the
          planet Neptune is about 2", whilst that of Jupiter is typically
          35".


          Moon
          Moon
          Moon

          The position of the moon is computed from the ELP 2000-85 lunar
          theory (Chapront-Touze and Chapront, 1988), which in turn is



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          fitted to the DE200/LE200 numerical integration of the Jet
          Propulsion Laboratory (Standish, 1981).

          Spot checks against the "Astronomical Almanac" again indicate
          that the mean error in the computed position of the Moon is about
          half an arc second, with peak errors around one arc second.


          Non-Stellar Objects
          Non-Stellar Objects
          Non-Stellar Objects

          For non-stellar objects, SkyMap uses the machine-readable version
          of the "Revised New General Catalog of Non-stellar Astronomical
          Objects" (Sulentic and Tifft, 1973), or RNGC.  This is a modern,
          revised and expanded version of the "New General Catalogue of
          Nebulae and Clusters of Stars" (Dreyer 1888).


          Time Corrections
          Time Corrections
          Time Corrections

          Because of the irregularities in the Earth's rotation, the
          theories of motion of astronomical bodies do not use Universal
          Time (GMT), but a uniform timescale called Terrestrial Dynamical
          Time (TDT).  SkyMap uses TDT internally for all its calculation
          of planetary positions, etc, but obviously the user specifies the
          time for which a map is required in UT (or rather, in local time,
          which is converted to UT).

          The difference between TDT and UT is called "delta T", and
          currently has a value of approximately 1 minute.  It is currently
          increasing at a rate of somewhat less than 1 second per year.
          The problem is that the value of delta T can only be determined
          historically (typically by analyzing the motion of the Moon), and
          current and future values can only be estimated, whilst values
          for the distant past (before the advent of modern astronomy) are
          uncertain to the order of many minutes.

          What this means in practice is that although the time of a total
          solar eclipse in the year 1500BC could be computed to a precision
          of a fraction of a second in TDT, the actual time in UT that the
          eclipse occurs (hence the places on Earth from which it is
          visible) will be uncertain to within several minutes.

          The "Astronomical Almanac" lists the values of delta T for every
          year from 1620 onwards (currently up to 1992), and provides
          estimates of its value for the current time.  SkyMap has all this
          data stored, and interpolates or extrapolates in this table to
          find values of delta T for dates between 1620 and 2000.

          For dates beyond the year 2000, an estimate of delta T is made
          using the method of L V Morrison and F R Stephenson, "Sun and
          Planetary System" vol 96,73 eds. W Fricke, G Teleki, Reidel,
          Dordrecht (1982).




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          For dates prior to 1620, an estimate is made using the method of
          F R Stephenson and M A Houlden, "Atlas of Historical Eclipse
          Maps", Cambridge University Press (1986).  They estimate the
          uncertainty to be 15 minutes at 1500BC.




















































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          Appendix B:  Dreyer Object Descriptions
          Appendix B:  Dreyer Object Descriptions
          Appendix B:  Dreyer Object Descriptions

          The RNGC catalogue of non-stellar objects includes the visual
          descriptions used by Johann Dreyer in his "New General
          Catalogue", published in 1888.  These descriptions are remarkable
          for their information content, but can be somewhat daunting at
          first.  For example, the Dreyer description of the globular
          cluster M3 in Canes Venatici is as follows:

               GCL,EB,VL,VSMBM,*11

          This can be translated as "Globular cluster, extremely bright,
          very large, very suddenly much brighter towards the middle,
          composed of 11th magnitude stars" - a pretty good description in
          only 19 characters!

          Similarly the galaxy NGC 2863 in Hydra is described as:

               CF,S,E,BET2*12,16

          which means "considerably faint, small, elongated, between two
          stars of magnitude 12 and 16".

          The description normally starts with a description of the
          object's brightness and size.  Dreyer adopted the scale used for
          this from Sir John Herschel, and the order used may be confusing
          to modern observers; for example, is "considerably faint"
          brighter or fainter than merely "faint"?  The other possible
          source of confusion is that 19th century astronomers often called
          a faint star "small" and a bright star "large", so one always has
          to be careful to judge whether a description such as "pretty
          small" refers to size or brightness!

          The scale used is as follows:

          Brightness                    Size

          EF   Excessively faint        ES   Excessively small
          VF   Very faint               VS   Very small
          F    Faint                    S    Small
          CF   Considerably faint       CS   Considerably small
          PF   Pretty faint             PS   Pretty small
          PB   Pretty bright            PL   Pretty large
          CB   Considerably bright      CL   Considerably large
          B    Bright                   L    Large
          VB   Very bright              VL   Very large
          EB   Extremely bright         EL   Excessively large

          Next normally comes a description of object's general shape.
          This lies on a scale ranging from "round" to "extremely
          extended", as follows:





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          Code      Shape

          R         Round
          VLE       Very little extended
          E         Elliptic or oval
          CE        Considerably extended
          PME       Pretty much extended
          ME        Much extended
          VME       Very much extended
          EE        Extremely extended

          By far the most cryptic part of the description, at first glance,
          is the group of letters giving what Sir John Herschel described
          as "the degree and rate of condensation".  A simple example is
          "GBM", meaning "gradually brighter towards the middle".  Looking,
          though, at NGC 4725, a galaxy in Coma Berenices, we find the
          dreadful looking "VSVMBMEBN"!  Even this mouthful, though, is
          fairly easily translated as "very suddenly very much brighter in
          the middle, with an extremely bright nucleus".

          When the descriptions give directions on the sky, the terms
          "preceding" and "following" are used for west and easy
          respectively.  To see what is meant by this, picture the way an
          object drifts across the field of view of a telescope if the
          drive is switched off.  Use of these terms is much more natural
          at the telescope eyepiece than the very confusing west and east,
          given the way that optical systems invert and/or reflect the
          field of view.

          Quite often the notes speak of groups.  The "1st of 4" is the
          first member of a group of four nebulae to drift across the field
          of view ie, the most western one, preceding all the others.  All
          members of a group will have very nearly the same declination.

          The complete list of abbreviations used in the Dreyer description
          of an object appears below:

          Code      Meaning

          AB        about
          ALM       almost
          AM        among
          APP       appended
          ATT       attached

          B         bright
          B         brighter (always coupled with another letter)
          BET       between
          BF        brighter toward following side
          BIN       binuclear
          BN        bright toward north side
          BP        brighter toward preceding side
          BS        brighter toward south side



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          C         compressed
          C         considerably
          CH        chevelure
          CL        cluster
          CO        coarse, coarsely
          COM       cometic
          CONT      in contact
          D         double
          D         diameter
          DEF       defined
          DIF       diffused
          DIFFIC    difficult
          DIST      distance

          E         extended
          E         extremely, excessively
          EE        most extremely
          ER        easily resolvable
          EXC       excentric

          F         faint
          F         following

          G         gradually
          GCL       globular cluster of stars
          GR        group

          I         irregular
          IF        irregular figure
          INV       involved, involving

          L         large
          L         little (adv.), long (adj.)

          M         middle or in the middle
          M         much
          MM        mixed magnitudes
          MN        milky nebulosity

          N         nucleus or to a nucleus
          N         north
          NEB       nebula
          NF        north following
          NP        north preceding
          NR        near

          P         poor
          P         preceding
          P         pretty (before F, B, L, S) (size and brightness blocks)
          PG        pretty gradually
          PLN       planetary nebula
          PM        pretty much
          PS        pretty suddenly



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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          QUAD      quadrilateral
          QUAR      quartile

          R         round
          R         resolvable
          RI        rich
          RR        exactly round
          RR        partially resolved, some stars seen
          RRR       well, resolved, clearly consisting of stars

          S         small
          S         suddenly
          S         south
          SC        scattered
          SEV       several
          SF        south following
          SH        shaped
          SM        smaller
          SP        south preceding
          ST        stars
          ST9       stars from the 9th magnitude downward
          ST9...13  stars from 9th to 13th magnitude
          STELL     stellar
          SUSP      suspected

          TRAP      trapezium
          TRI       triangle, forms a triangle with
          TRIN      trinuclear

          V         very
          VAR       variable
          VV        very very,  an intensive of V

          *         a star (or stars)
          *10       a star of 10th magnitude
          **        double star
          ***       triple star
          ()        items questioned by Dreyer enclosed in parentheses
          "         arc seconds (two "not-equals" in published catalogue)
          '         arc minutes (one "not-equals" in published catalogue)
















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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          Appendix C:  SkyMap Release History
          Appendix C:  SkyMap Release History
          Appendix C:  SkyMap Release History


          29-May-93 v1.3

          New features:

          The program can now display non-stellar objects.  The database
          used is the Revised New General Catalogue (RNGC).

          Constellation boundaries can now be displayed.

          The printing options have been greatly expanded.  When a map is
          printed the user can now select whether to print the entire map,
          or the current zoomed view, and also whether to print in black
          and white or colour.  For colour maps a dialog allows the user to
          select the colour of each component of the map.

          All map features are now present on both the horizon and sky area
          maps (eg star labels can now be displayed on the horizon map).
          The user interface has been made more consistent between the map
          types.

          The program now has an optional ToolBar at the top of the screen,
          which provides short-cuts for the commands on the "View" menu.

          The program now (finally!) has a complete on-line help system.
          This is basically a copy of the manual.

          Bug fixes:

          I'd forgotten to apply the correction for diurnal parallax to
          planetary positions on the Sky Area map.  Consequently, the
          planets were being shown in their geocentric, rather than
          topocentric positions, resulting in errors of up to 2 degrees in
          the apparent position of the Moon.  Fixed.

          The size of the image of the Sun and Moon on the Sky Area map was
          being incorrectly calculated, resulting in images that were about
          50% too large when the map was printed on a portrait orientation
          page.  Fixed.


          07-Mar-93 v1.2

          New features:

          Added a new "Sky Area" map type, centred on a right ascension and
          declination.  This is intended to be used to draw a detailed map
          of a small region of the sky.

          Added the ability to display photographic images in either GIF or
          BMP format.  Images can either be explicitly opened, or



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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          associated with specific objects (currently planets) and
          automatically displayed.

          Bugs fixed:

          Single pixel stars were being printed on the printer in the
          screen colour, which almost certainly mapped to white on the
          printer, resulting in them not being printed.  On a mono print,
          single pixel stars are now correctly printed black.

          When the right mouse button was pressed over a horizon map to
          display the pop-up menu, then the *right*, rather than the *left*
          button pressed (ie, a user input error!) an incorrect cursor
          position was stored.  If the left button was subsequently used to
          select an information dialog a wildly inaccurate position or a
          GPF resulted.  This is probably the cause of all the "random
          number" errors previously reported.  Thanks to Don Munro for
          tracking down a reproducible case of this puzzling error!  Fixed.

          Removed the incorrect, uninitialized data displayed on the
          information dialogs for the Sun and Moon. (Eg phase 0.000 for the
          Sun.)


          05-Feb-93 v1.11

          Bugs fixed:

          When the start of a constellation figure was off the edge of the
          map, the first visible line of the constellation was being drawn
          incorrectly in certain circumstances.  Fixed.

          The correction for refraction was being correctly calculated and
          correctly displayed in the "About" box for a star, but not
          applied to the plotted position of the stars on the map.  This
          led to stars being plotted with slightly too low an altitude (the
          maximum error being about half a degree at the horizon).  Fixed.

          If the star position calculation was aborted by the user pressing
          the "Cancel" button, the subsequent constellation figure setup
          calculation code displayed an error message for each star it was
          unable to find.  Pressing the "Cancel" button now aborts the map
          calculation cleanly.


          31-Jan-93 v1.1

          Release to BIX only for testing.

          New features:

          Version 1.0 of SkyMap simply plotted stars in their mean catalog
          position.  This version now rigorously calculates the apparent



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                  SkyMap v1.3  Copyright (c) 1992-1993 C A Marriott


          place for the time of observation, correcting for proper motion,
          aberration, precession, nutation, and refraction.

          Added code to verify that dates are in the range 4000BC-8000AD
          (the range over which the planetary position equations are valid.

          Bugs fixed:

          In the "Observer" dialog, the "Time Difference" edit field was
          only wide enough to allow two digits to be entered, making the
          program not too useful for anyone outside the GMT time zone.
          Fixed.



          24-Jan-93 v1.0

          Release of SkyMap 1.0, with basic facilities for drawing horizon
          map and plotting planetary and lunar positions.





































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