Club Amiga de Montreal - CAM/CAM_CD_1.iso/files/015.lha/StarChart.DOC

Text File | 1986-11-10 | 16KB | 365 lines

                                StarChart
                               Version 1.0
                                    by
                               Ray R. Larson
                            Copyright (c) 1987


I. About StarChart

   StarChart is a program that lets you display and identify about 600
stars, galaxies and nebulae visible in the Northern hemisphere. This
version of StarChart was written in Aztec C by Ray R. Larson. The star
data and original concept are derived from an AmigaBasic version by
Robert L. Hill of the Orange County, Calif. Amiga Friends User Group.

  StarChart may be freely copied and distributed, but may not be sold
without the permission of the author. Nominal charges for duplication
are excluded. Feel free to copy this program and give it away, but
please retain the above notice.

   The author can be contacted at the following addresses:

 Ray R. Larson
 6425 Central Ave. #304
 El Cerrito, CA 94530

 BITNET - LARSON@UCBCMSA
 CompuServe - 70446,766
 The Well - rrl


This documentation file simply reproduces the help messages available via
menu selections in the StarChart program.


II. Using StarChart

   StarChart will only run under AmigaDOS 1.2, and requires about
120K of free memory. It will take advantage of expanded (FAST) memory
and will permit multitasking (However, it does change some of the color
registers, so concurrent tasks may show up with different colors. The
default (preferences) colors are restored when you exit from StarChart.)
StarChart may be run from WorkBench by double-clicking the StarChart Icon,
or from the CLI by typing 'StarChart'.

A. The Display

   The initial display shows a Northern view of the sky from Southern
California at about 11:00 p.m. on September 18, 1986. This initial
display can be set for any location, time, date, and view by setting
the desired values in the Parameters requester and saving them to a file
called DEFAULT.STAR.  If the DEFAULT.STAR file is found in the current
directory when StarChart is started, the saved values are used to
calculate the initial display.  For more information on setting and saving
parameters, select the 'HELP for Parameters' item in the Parameters menu.

  Note that this program must map one quarter of the celestial sphere onto
a (relatively) tiny flat screen, so stars appear much closer together than
they do in the sky. The stars visible in the lowest portion of the screen
would be on the horizon, the stars at the top of screen would appear at
your zenith (directly overhead). The center of the screen is due North
(or due South, depending on the horizon set), and the sides are East or
West. Each inch on the screen represents about 15 degrees of arc.

  The text at the bottom of the screen shows your current viewing
location (Latitude and Longitude), the date, and the siderial time.
Siderial time is based on Greenwich Mean Time (GMT) corrected for your
location. The stars displayed are automatically updated for each hour
of siderial time that passes. You can change the rate of this simulated
time using the Options menu.

B. Identifying Stars and Constellations

   To display the name and star data for a particular star, position the
'starburst' mouse cursor so that the star shows as a white or blue spot
in the center of the cursor and click the LEFT mouse button. A window will
open showing the common name, Greek name, constellation, position
(Right Ascension and Declination), relative brightness (Magnitude),
distance from Earth, and comments on the color and name of the star,
galaxy or other stellar object. The selected star will be circled on the
display and highlighed in magenta while the star data is being displayed.
You can move and resize the star data window using the usual window
gadgets. Clicking on 'CONTINUE' will either close the window and return
to the normal display, or show additional star data if two or more stars
happen to be too close together to distinguish on the display.
  Clicking the RIGHT mouse button over a star will highlight all of the
stars in the constellation to which that star belongs, and the name of
the constellation will be shown in the title bar of the screen.

  Additional functions (and there are a lot of them) are accessed by
menu selections. Information about those functions can be seen by
selecting the 'HELP' item in each menu.

  Click on the close gadget in the upper left of this screen to return
to StarChart.



                           Project Menu Help

   Selections in the Project menu provide general information about
the Starchart program, what you are seeing, and how to use it, and
additional ways to identify stars and constellations.

1> About StarChart ...

   Selecting this menu item will display information about the Starchart
program, how to interpret the display, and how to use the mouse to
identify stars and constellations.

2> Locate Star by Common Name

   Selecting this menu item will bring up a text requester. Type in the name
of the star you wish to locate and press return. If the star is visible
it will be circled in magenta and blink in red. The complete star data will
then appear in a window. Click on the word CONTINUE at the bottom of the
information window to close the window and return to normal operations.
If the star you are looking for is not in the star table, a message stating
that will appear in the title bar of the screen. If the star is in the
table, but not currently visible, a message stating that will appear in
the title bar and also in the star information window. You can use the
Options menu to choose how stars located in this way will be displayed
(blink only, blink and star data, star data only).

3> Locate Star by Greek Name

   Selecting this menu item will bring up a text requester similar to
the Locate by Common Name item. The display functions are the same as
above. The Greek name of a star is composed of two parts, a Greek letter
and a constellation name. An example is ALPHA CENTAURI. The Greek letter
represents the apparent magnitude (brightness) of the star in the given
constellation. Thus ALPHA is brightest, BETA is next brightest and so on.
The Greek alphabet is:
        ALPHA, BETA, GAMMA, DELTA, EPSILON, ZETA, ETA, THETA,
        IOTA, KAPPA, LAMBDA, MU, NU, XI, OMICRON, PI, RHO, SIGMA,
        TAU, UPSILON, PHI, CHI, PSI, OMEGA
Use the spelled out name of the letter in searching (you don't have to
capitalize them). The program tries to avoid problems with Greek grammar
by ignoring the last two characters of the constellation name (for example
ALPHA CENTAURI, ALPHA CENTAURUS, or even ALPHA CENT will find the same star.
The constellations available can be viewed by going to the Constellation
menu.

4> Constellation Menu

   Selecting this menu item changes the available menus to the constellation
search menu. See the HELP item in the constellation menu for more
information on searching for constellations.

5> Help

  Selecting this menu item brings up this set of help messages.

6> Exit

  Selecting this menu item ends the StarChart program and returns you to
WorkBench (or wherever you came from before starting).




                             Parameter Menu Help

   The Parameters menu items let you change the location, date and time,
and viewing direction for your viewing position on Earth.

1> Set Parameters

   Selecting this menu item brings up the parameters requester window.
The parameters requester shows the values currently set for your viewing
location, date and time, and horizon view. To change any of the values
click on the value you want to change using the left mouse button. You
can then use the keyboard to type in new values. The DEL and BACKSPACE
keys can be used to delete values in each item. The program will only
let you enter numbers within the ranges indicated, and will only accept
numbers. If you enter a number outside of the acceptable range, the
screen will flash and a red question mark '?' will appear next to the
item with an invalid value. You will not be able to exit the requester
until all items are within the acceptable ranges. (You can, however,
click on CANCEL to escape from the requester and ignore all changes.)

   The parameters that may be changed are:
Longitude (degrees and minutes West(+) or East(-) of the Prime Meridian.)
Latitute  (degrees North of the Equator)
Date      (the year, month and day)
Time      (Hour, minute, and seconds for your local time on a 24 hour clock
           the siderial time will be computed from these values).
Horizon   (Click on NORTH for a Northern view, SOUTH for a Southern view
           from your location, the current view will be highlighted.)

  When you have changed all the parameters you want, click on the OK
at the bottom of the requester. The requester will vanish and the star
positions for the requested location, date, time, and view will be
calculated, and the star chart re-drawn.

2> Save Parameters

   Selecting this menu item will bring up a requester for a file name.
The name provided in the requester, DEFAULT.STAR, is a special file
that is used (if available) to calculate the initial star display when
StarChart is started. You can modify the file name to whatever you
wish, then press return to save the current location information.
(In the next version of StarChart, this will be replaced by a nicer
requester, and more save and retrieve features will be added. Stay tuned.)

3> Restore Parameters

   Selecting this menu item will reset your viewing location, etc., to
the initial start-up values. If the location information was read from
the DEFAULT.STAR file, the file will be re-read. This means that if you
have replaced the DEFAULT.STAR file with updated parameters, those new
parameters will be read when you select restore.

4> Help for Parameters

  Selecting this menu item displays this set of help messages.




                                Options Menu Help


   The Options menu provides several options for choosing how stars will
be displayed in the StarChart program.

1> Change Magnitude Display Levels

   Selecting this menu item calls up a requester that will let you set
the magnitude for different types of display on the main star chart.
Magnitude is a measure of the relative brightness of stars. It ranges
from slightly less than zero for the brightest stars to over 15 for very
dim (and distant) objects such as remote galaxies. The two values presented
in the magnitude requester can be changed to indicate the HIGHEST magnitude
values that will appear as a small plus sign '+', or as a white dot in the
display. All stars with magnitudes higher than the maximum value selected
for a white dot display will appear as blue dots. Using the magnitude
settings you can tailor the display to show, for example, only the stars
that would appear in a bright city sky (by setting magnitude for plus
to about 2.5 and magnitude for white dot to about 2.9. The default startup
settings for magnitude are 2.0 for plus and 5.0 for white dot.

2> Change Siderial Clock Speed

   Selecting this menu item brings up a request that lets you set the
speed that apparent time passes in the StarChart program. Normally, one
second of 'real' clock time passes for each second ticked off on the
siderial time display at the bottom of the StarChart screen. The clock
speed set for this normal time display is 1 -- that is 1 second of
simulated time for each second of real time. This ratio can be changed
up to 1800 seconds (a half hour of simulated time) for each second of
real time. Setting the simulated time that high means that the display
will be almost continually re-calculated and redisplayed, since the display
is automatically updated for each hour of simulated time that passes.
When you have a Northern horizon set, and a high simulated time ratio,
you can see how the stars rotate around Polaris, the Pole Star.


The following three menu items govern what sort of display is given when
a star is searched for by common name or by Greek name. They do not affect
the display given when selecting stars or constellations using the mouse
buttons.

3> Display Both Star and Info

   Selecting this menu item shows that located stars will be highlighted
and blinked on the screen, and then the full star data for the star will
be shown.

4> Display Star Only

   Selecting this menu item inhibits the display of the full star data.
Visible stars located will be blinked, but no additional data will be
shown. If the star is not visible a message to that effect will appear
in the title bar of the screen.


5> Display Info Only

   Selecting this menu item inhibits blinking of the located star, but
the full data will be shown regardless of whether the star is currently
visible.

6> Help for Options

   Selecting this menu item displays this set of help messages.





                        Constellation Menus Help

   The Constellation menus provide ways of searching for constellations
and for showing different groups of stars such as the Zodiac constellations,
Messier objects and NGC galaxies. There are four menus in the constellation
menus set. The first is discussed below. The other three menus contain the
names of the sixty constellations that can be identified by the program.
  To see any of these sixty constellations, just select it's name from one
of the menus. The name (and meaning of the name) will be shown in the title
bar, and all of the stars of the constellation will be highlighted in red.

Constellation Options Menu

  The first menu gives a number of options governing how the star information
for constellations is displayed.

1> Display Stars Only

   Selecting this menu item (the startup default) will simply highlight
all of the stars of a selected constellation in red, and show the name
and meaning in the screen title bar.

2> Display Both Stars and Info

   Selecting this menu item will highlight the stars of the constellation
as above, and then will highlight and circle each individual star in the
constellation and show the full star data for that individual star. If
particular stars of the constellation are not currenly visible (i.e. below
the horizon) the star information will still be given with a note that the
star is not currently visible.

3> Display Info Only

   Selecting this menu option will show only the star data for the stars
in the constellation. However, each visible star will be highlighted as
the information for that star is shown.

4> Display Major Stars Only

   Selecting this menu item will show only the major stars of each
constellation (in any of the display modes above). The major stars are
those identified with a Greek name. If you select this option, stellar
objects that are IN a constellation, but not considered part of it, will
NOT be displayed.

5> Show Zodiac Constellations

   Selecting this menu item will highlight all of the visible constellations
of the Zodiac in red. Then each individual visible constellation will be
blinked in blue and magenta and its name will be shown in the title bar
of the screen.

6> Show Messier Objects

   Selecting this menu item will display all of the objects of the Messier
catalog (galaxies, nebulae, etc.) that are included in the program. They
will be highlighted in red.

7> Show NGC Galaxies

   Selecting this menu item will display all of the objects of the New
General Catalog (NGC) of galaxies, nebulae, etc. that are included in the
program. They will be highlighted in red.

8> Constellation Menus Help

   Selecting this menu item will bring up this set of help messages.

9> Return to Main Menu

   Selecting this menu item will restore the main StarChart menu.