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1990-10-08
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SKYCHART sky planetarium ...
----------------------------
This program is a demo of a PC planetarium under OS/2 (1.1 and up).
Registration for the DOS version.
---------------------------------
There is also a DOS version available when you register for $30. Then you get
a solar and lunar eclipse program too (range from 1100 AD to 2700 AD).
The DOS version requires DOS 3.00 or higher, 384 KB of RAM and an EGA, VGA or
Hercules card. 800x600 VGA mode is also supported. CGA is only supported in a
limited way (because of the too low vertical resolution). This version also
runs fine under any 386 DOS multitasker, including OS/2 2.0. The planet
calculation and zoom functions are much faster when a math coprocessor is
installed. The functionality of the DOS version is exactly the same, and also
consists of pop-ups menus and help. The DOS version is much faster because of
the large overhead for plotting dots under OS/2. (When run in a window of
DesqView/386 or OS/2 2.0 the performance is slow, because of the video
virtualization, but most users don't use this.)
Even on an 8 MHz XT the performance of the running sky is adequate. A planet
phenomena program and routines to calculate high planetary and lunar
positions is under development now.
How it works.
-------------
The program shows half the visible sky at a time as a 'dome'. Any direction
can be the middle. When South is in the middle, the program shows the sky
from east to west through the South and until the zenith. Animation (a
running sky as in a planetarium) is also possible. For fast loading, all the
star and planet data is hardcoded in the EXE file rather than in separate
files.
This program is a true OS/2 program, so it does not run under DOS or the DOS
compatibility box. Requirements: OS/2 version 1.1 or higher (including the
2.0 beta release), IOPL=YES (or IOPL=SKYCHART) in CONFIG.SYS (or CONFIG.OS2).
Note on palettes:
The last requirement because of the fact that palette modification is not
supported by the current versions of PM, so I included an IOPL routine for
modifying the palette registers directly. This works only with (super-) VGA
and when the -c switch is set. When skychart is the active window, some
colors of other windows can be changed. When Alt-Esc or Ctrl-Esc is pressed
or another window is selected by the mouse, the default PM palette is
restored. I use the palette modification for smooth and fast color change of
the sky background when it gets dark and of change the color of the setting
Sun or Moon.
Range:
- Date from 1700 to 2100.
- Location anywhere on Earth between 89 degrees latitude North and South.
- Precession and proper motion between 9800 BC and 13800 AD (no planets).
Accuracy:
This is not a high accuracy program. The accuracy is sacrified for the speed
to animate a planetarium. But high accuracy moon and planet calculation
routines are under construction now.
- Rise and set one minute (for the Moon sometimes a few minutes).
- Moon phases one minute.
- Star/planet positions: 1/4 degree (can be worse when the date is close to
1700 or 2100 or when the latitude is close to 89 degrees.) When zoomed out,
the accuracy is much better with sacrifice of speed when no coprocessor is
present.
Command line switches:
SKYCHART nnn <switches>
nnn is the location code. This three letter location code can be found in
LOCATION.DAT.
-c: Enable color palette changes for sky background color change and color
change for low Sun and Moon (VGA and Super VGA only).
-w: Start up SKYCHART in a window rather than in full screen (maximized).
-thh mm
Time difference of your computer's real time clock and GMT. When your
time is behind GMT (as in the U.S.) add 24 hours. E.g. for PST specify
-t16, for PDT -t17.
In the program the F10 key toggles the title bar+menu bar on and off.
Help is available by pressing F1, and item specific help is available by
highlighting a menu (by pressing Alt and moving the arrow keys) item and
then pressing F1.
When the sky is dark enough, a cross is displayed when the mouse pointer
within the sky dome. Pressing Enter or the Left mouse button searches the
nearest object (not Sun and Moon) and displays some information about this
object (planet or star) in a message box.
Note: The Esc, F or F10 options stated in the Zoom help text do not apply to
this version. When the mouse pointer is inside the sky dome, the 'Z' key or
th right mouse button zooms a part of the sky around the mouse pointer and
shows all stars until magnitude 7.0.
The REAL sky is even more beautiful.
------------------------------------
When it's dark outside and the sky is clear (especially when you are far from
big cities), please go outside and watch the output of this program in the
real sky rather than on this computer screen. This program does NOT match the
beauty of the night sky and is just a tool for cloudy nights (of which there
are many here in Holland...).
LOCATION.DAT
------------
This text file can be edited by any ASCII text editor to put your own custom
locations in the file. On the top of the file is stated how to do that. This
file should be in the same directory as SKYCHART.EXE.
Known problems.
---------------
When the sky is running in animation mode and a task switch is performed
(e.g. Ctrl-ESC or Alt-ESC) the program sometimes first overwrites other
windows with stars and then clears them.
Authors:
Hans Bloemendaal
Klaas van Ditzhuyzen
Corona Borealis Public Observatory
Hogestraat 12
Dieren Holland.
or leave a message for Klaas (via /839) on Gilmore BBS
(805) 581-1275
Acknowledgements:
-----------------
YALE star catalog (epoch converted from 1875.0 to 2000.0)
Jean Meeus: Astronomical Formulae for Calculators (1982)
Jean Meeus: Tables for Sun and Moon (1961)
Microsoft C Compiler Version 6.00
Microsoft OS/2 Programmer's Toolkit Version 1.2
NuMega Technologies Soft-ICE 2.5 (for the DOS version)
NuMega Technologies MagicCV 3.00 (for the DOS version)
Tandon 386/16 PC and Compaq Systempro 386/33.