StarChart version 2.0 by Tim Wentworth, January 10, 1987.
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StarChart is a standalone program that will plot a portion of the night
sky on the Macintosh screen.  Several new features have been added to
this version of StarChart.  Here is how to use the program:

1. StarChart will plot a section of the sky based upon information given
to it by the user.  Under the StarChart menu, you will see four menu
options.  The first is Plot New Chart....  After choosing this command,
you will see a dialog box where you can enter three numbers, View Angle,
Right Ascension and Declination.  If you don't know what these terms
mean, the picture may help you.  Note that the View Angle must be between
1 and 360, Right Ascension must be between 0 and 24, and Declination must
be between -90 and 90.  Click the mouse on Plot to begin plotting that
portion of the sky.

2. The next menu choice under the StarChart menu will bring up a list of
the 88 constellations.  StarChart will plot the section of the sky that
contains the constellation that you choose.

3. The next menu choice will list Messier objects.  StarChart will plot
the section of the sky that contains that Messier object.  The object
will be plotted at or near the center of the screen.

4. The next menu choice will list popular star names for 88 of the
brightest stars in the sky.  As above, after choosing one of these,
StarChart will plot that portion of the night sky.  The star chosen
will be plotted at or near the center of the screen.
 
5. StarChart will take from a few seconds to several minutes to plot
the sky.  The plotting time depends on the coordinates given.
Generally, the farther away from 0 the declination gets, the longer
the plotting time.  Also, larger view angles will increase the plotting
time.  Just click the mouse if you wish to cancel the plot at any time.
 
6. After StarChart has finished plotting, you may retrieve data about
any object on the screen by pointing to it with the mouse and clicking.
A menu will appear in the menu bar that contains information on that
object.  If the star does not have a popular name, the title of the
menu will be its abbreviated Greek designation.  For example, the star
"Beta Scorpio" would be abbreviated "BETSCO".  The Greek letter usually
represents the rank in brightness in that constellation.  For example,
"Beta Scorpio" would probably be the second brightest star in the
constellation Scorpio (but this is not always true).  If the star does
have a popular name, that name will be the title of the menu, and its
Greek designation will be the first entry under the menu bar.  Below
this information is the Right Ascension, Declination, Magnitude and
Color Index of the star.  The magnitude will range any where from -.1
to 9.9, the larger the number, the less bright the object.  (A few
Messier objects had magnitudes above 9.9.  These were entered in the
database as "9.9".)  The Color Index is an indicator of the color of
the star.  It ranges from -.25 to +2.5.  A lower number means the star
is bluer; a higher number means the star is redder.  Note that Messier
objects do not have a Color Index.
 
7. Under the "Draw" menu is the option "Draw Grid".  Choosing this
option will draw a labeled grid across the screen, with lines
representing hours of Right Ascension and 10 degrees incriments in
declination. This facilitates star-hopping with a telescope.
 
8. By holding down the command key, you may draw straight lines across
the screen.  This is useful for outlining constellations or other
objects.  The lines that you draw may be erased with the "Erase Lines"
option in the "Draw" menu.
 
9. The third option under the "Draw" menu allows you to invert the screen
so that the stars appear black on a white screen.  This is useful in
case you want to print the contents of the screen using the Command-
Shift-4 key combination.
 
10. The "Brightness" menu allows you to selectively plot certain
magnitudes of stars.  All magnitudes of stars will be plotted if "Plot
All Stars" is chosen.  If you wish to see only stars between magnitudes
2.0 and 2.9, choose that option.  Note that you can choose any
combination of magnitudes; for example you can choose to see only stars
brighter than 1.0 and dimmer than 5.0.  Choosing "Plot All Stars" cancels
all options previously selected.  Note that limiting the stars that
StarChart has to plot speeds up the plotting greatly.
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Modifying StarChart
 
You may modify StarChart if you are familiar with a few Macintosh
utilities such as ResEdit and FEdit.
 
1.  The StarChart database is contained in the data fork of the program.
This may be accessed using a program such as FEdit and opening the
data fork.
 
2.  The data is ordered by right ascension, from 0 to 24 hours.  The
format of the data is:
 
ALPLEO 10084+1158+1.4 -0.11 178
 
starname (6 characters)
space
right ascension (5 digits)
declination (4 digits plus sign)
magnitude (floating point number plus sign)
space
color index (floating point number plus sign)
space
popular star name index (3 digits)
 
3. If you are unhappy about the coordinates of any object, you may use
FEdit to change those numbers.  Likewise with the magnitude or the
color index of a particular object.
 
4. When you choose to plot a constellation, Messier object or star by
popular star name, StarChart looks up the coordinates of that object
in a STR# resource.
 
STR# 128  Constellations
STR# 129  Popular Stars
STR# 130  Messier Objects
 
Following each name is the view angle, right ascension and declination
in integers that StarChart uses to plot the general area of the sky 
that contains that object.  Using a program such as ResEdit, you may
change or fine tune any of these numbers to your liking.
 
5. 233 of the stars in the database have popular star names.  This name
will appear in the menu bar whenever you click on that star with the
mouse.  The list of popular star names is not exhaustive; there are
probably others that have not been included.  It is possible to add
a popular name to a star this way:
 
First, the last three digit number in the data base for any particular
star is its popular star name index.  See above: the index number for
Alpha Leo is 178.  This means that the popular star name for Alpha Leo
is the 178th string in STR# resource 131.  If a star does not have a
popular star name, the index number is 000.  By changing this number
(using FEdit) and adding another string to STR# 131 (using ResEdit)
you can add your own popular star names.  Warning: the first index
number you should use should be 234, since 1 through 233 have already 
been used.
 
Since many stars have different popular star names (depending on the
culture that originated the name) you may also wish to simply change
the popular star name already contained in STR# 131.
 
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StarChart may have trouble when used on a 128k Macintosh.  The program 
may crash when used under these conditions.  Please make a backup
first before running the program so you won't have to re-download.

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StarChart 2.0 is public domain, is not copyrighted, and may be used and
passed on freely.  I would be interested to hear any comments you 
have on StarChart 2.0.  You may leave mail for me on:

CompuServe  74146,2362
Genie       WENTWORTH

Enjoy the program.  Tim Wentworth.