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/--------------------------------------------------------------\
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| StarWorks |
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| Planetarium Simulator |
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| User Guide |
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| Copyright 1993 |
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| Sci-Vision |
| PO Box 941532 |
| Suite 269 |
| Dallas, Texas |
| 75094-1532 |
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| |
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| Document Revision 2.01 |
| |
| Printed December 13, 1993 6:45 PM |
| |
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| |
\--------------------------------------------------------------/
Table of Contents
Introduction 1
Horizon Display Description 2
Zenith Display Description 3
Sky Map Display Description 4
Orbital (zenith) Display Description 5
Orbital (ecliptic) Display Description 6
Jupiter's Moons Display Description 7
Planet Size Display 8
Planet Position Display 8
Planet Distance Display 8
Planet Rise Times Display 9
Pick Mode 9
Find Mode 11
Menu Screen Descriptions 11
Main Menu 12
Setup Menus 13
Time Setup Menu 14
Star Setup Menu 14
Planet Setup Menu 15
Location Setup Menu 16
Trails Setup Selection 16
View Direction Setup Selection 16
Zenith View Angle Setup Menu 17
Sky Window Setup Menu 17
Save Setup Selection 17
Restore Setup Selection 18
Files used by StarWorks 18
STARFILE 18
COMETFIL 19
STARWORK.MNU 19
Technical Notes 19
Program Call 20
STARWORKS Environment Variable 21
GMT / Local Time /Daylight Savings Time 21
Phase 22
Altitude and Azimuth 22
AU Astronomical Units 23
Formulas used by the program 23
Development System 23
Program Accuracy 23
Astronomical Experiments 23
Caveats 25
Terms of License 26
Copyright Notice 26
Introduction
StarWorks is a program which provides astronomical simulations
the same way as seen in a planetarium. StarWorks will show the
past, present and future skies as viewed from anywhere on Earth.
The program will display the position (with real time updating)
of the planets and comets in orbit around our Sun as well as
calculate specific data about celestial bodies. StarWorks will
even display the moons of Jupiter as they orbit the planet.
Program options allow the user to select the date and time to
view, the direction of view, the viewer's latitude and longitude
on Earth, and much more. Using the display updating parameters
StarWorks can display a complete day's movement of the heavens,
or demonstrate the retrograde motion of the planets.
StarWorks will run on any DOS based system (DOS version 2.0 or
greater) which has SuperVGA, VGA, EGA, CGA or Hercules graphics
and a hard disk. Note that although the program will run in CGA
mode, the display quality is poor because of the lack of resolu-
tion and colors.
StarWorks will run with or without a math co-processor, however,
it can be very slow without one because of the intense floating
point arithmetic involved.
If the version number displayed on the first screen ends with
'(Limited),' this version of StarWorks is being distributed as a
Limited Demonstration version. Its only limitations are that it
will work for a limited date range and that it includes fewer
stars/objects in the data base. The Full Function version will
work between the years 1700 and 2500. The full function version
also includes over 11,000 stars and messier objects.
The Full Function version can be requested by sending a support
donation using the form at the end of this document.
Horizon Display Description
The Horizon display attempts to show the sky as seen from Earth
when looking in a specified direction at a specific time of day.
The left side of the display is what would be seen over your left
shoulder as is the right side over your right shoulder. The top
of the display shows what you would see directly over your head.
Because of the transformation from 3-dimensions to 2-dimensions,
the distortion increases as you approach the edges of the arc.
Another way to think of what the display is representing is image
you are sitting in the middle of the planetarium. You see in
front of you half of the dome. The difference is that at the
planetarium your field of view would not be large enough to see
the complete half dome all at one time. With the program the
complete half dome is compressed onto the flat screen.
The Moon is drawn in its approximate phase with the New Moon
represented with an empty circle. The drawing of the phase of
the Moon is rounded to the nearest quarter (New, First Quarter,
Half, Third Quarter, Full, etc.).
By using menu selections you can control the brightness/size of
the stars/objects, direction of view, select Real Time display
or a User Defined time, change the update rate of the display and
much more.
Note that the time and date displayed at the top of the screen
represent Local Time and assume that the system clock is set to
daylight savings time when applicable (see technical notes for
more details on daylight savings time). When 'Leave Trails' is
turned on the time/date displayed on the left is the start time
and the time/date on the right is the current time.
CONTROL KEYS for this display are:
p : Pause the updating of this display and put the
display in PICK mode (See Pick Mode)
Escape: Exit Pause/Pick Mode.
Enter : Pick Star (while in Pick Mode). Any key press
releases pick.
t : Toggles whether objects leave a trail as they move
s : Toggles between Local Time and Sidereal Time
o : Outline the Constellations (In Pick Mode)
l : Dump current screen to an IBM compatible printer
(Best results are obtained in EGA Mode)
left/right arrows: scroll display view to the left/right.
(changes view direction)
Zenith Display Description
The Zenith display attempts to show the sky as seen from Earth
when looking directly over head at a given time of day from a
specified location on Earth.
The top of the displayed circle represents the compass direction
of North, the bottom of the screen is South, Right is to the West
and the left side of the circle is toward the East horizon.
Keep in mind that distortion increases as you approach the edges
of the circle, especially for wide View Angles.
The Zenith View Angle specifies the lowest altitude an object may
be at and still be plotted on the display. For example, if Zero
is entered, then all object whose altitude is currently above the
horizon will be plotted. If 89 is entered, only objects whose
current altitude is greater than 89 degrees will be display. Thus
only objects within one degree of vertical to be displayed.
The Moon is drawn in its approximate phase with the New Moon
represented with an empty circle. The drawing of the phase of
the Moon is rounded to the nearest quarter (New, First Quarter,
Half, Third Quarter, Full, etc.).
By using menu selections you can control the brightness/size of
the stars, direction of view, select Real Time display or a User
defined time, change the update rate of the display and much
more.
Note that the time and date displayed at the top of the screen
represent Local Time and assume that the system clock is set to
daylight savings time when applicable (see technical notes for
more details on daylight savings time). When 'Leave Trails' is
turned on the time/date displayed on the left is the start time
and the time/date on the right is the current time.
CONTROL KEYS for this display are:
p : Pause the updating of this display and put the
display in PICK mode (See Pick Mode)
Escape : Exit Pause/Pick Mode.
Enter : Pick Star while in Pick Mode. Any key press
releases pick.
t : Toggles whether objects leave a trail as they move
s : Toggles between Local Time and Sidereal Time
o : Outline the Constellations (In Pick Mode)
l : Dump current screen to an IBM compatible printer
(Best results are obtained in EGA Mode)
Sky Map Display Description
This display is used to create a Sky Map located at given Right
Ascension/ Declination coordinates. All objects within the
boundaries of the window are displayed. This display is useful
for 'zooming' in on a region of the sky the same way a more
telescope would be able to zoom in on a particular area of the
sky.
The initial center and width of the display are determined from
the values entered into the menu. The width is interpreted as the
amount of right ascension covered from the left side of the
window to the right. The amount of declination covered in the
display is calculated automatically to give the correct scaling.
The scaling factor also takes into account the aspect ratio of
the display device.
While viewing the sky map, the center of the display can be
shifted in Right Ascension using the left/ right arrow keys and
can be shifted in Declination using the up/ down arrow keys. The
window width can also be increased or decreased using the '-' and
'+' keys.
Note that star brightness/size is controlled as described for the
Horizon and Zenith displays and the time/date are displayed as
described for the Horizon and Zenith displays.
CONTROL KEYS for this display are:
Left / Right Arrows : Pan Display Window Left / Right
Up / Down Arrows : Pan Display Window Up / Down
+ : Zooms in on the Center of the Window
- : Zooms out from Center of the Window
m : Toggle Between Current View and Full-Sky View
p : Pause the Updating of the Display
and Enter Pick mode.
Enter : Select Object at Cursor (Pick Mode)
t : Toggles whether objects leave a trail as they move
s : Toggles between Local Time and Sidereal Time
f : Finds object matching user entered name (Object Find)
o : Outline the Constellations (In Pick Mode)
l : Print Current Display to Print Device
ESC : Exit the Display
Orbital (zenith) Display Description
This attempts to show the position of the planets and comets as
they orbit the Sun. The view is from above the plane of the
solar system with planets moving counter clockwise around the
Sun.
By using the control keys you can zoom in toward the Sun or back
away from it. The 't' key toggles whether the planets leave a
trail as they move. The control keys will also allow you to
freeze motion.
Note that the time and date displayed at the top of the screen
represents Local Time and assumes system clock is set to day-
light savings time when applicable (see technical notes for more
details on daylight savings time). When 'Leave Trails' is turned
on the time/date displayed on the left is the start time and the
time/date on the right is the current time.
CONTROL KEYS for this display are:
p : Pause the updating of this display and enter
Pick Mode
Enter : Select Object at Cursor (Pick Mode)
t : Toggles whether planets leave a trail as they move
+ : Zooms in on the Sun
- : Zooms out from the Sun
* : Zooms out from the Sun (x10)
r : Restore Default Zoom value
l : Dump current screen to an IBM compatible printer
(Best results are obtained in EGA Mode)
Orbital (ecliptic) Display Description
The Ecliptic Orbital Display attempts to show the position of the
planets and comets as they orbit the Sun. The perspective of
this view is the ecliptic plane of the solar system. It is viewed
edge-on as seen from a position at the bottom of the screen on
the Orbital (zenith) Display.
By using the control keys you can zoom in toward the Sun or back
away from it. The 't' key toggles whether the planets leave a
trail as they move. The control keys will also allow you to
freeze the motion of the planets.
As in all displays, the Escape key exits from the display.
Note that the time and date displayed at the top of the screen
represents Local Time and assumes system clock is set to daylight
savings time when applicable (see technical notes for more de-
tails on daylight savings time). When 'Leave Trails' is turned
on the time/date displayed on the left is the start time and the
time/date on the right is the current time.
CONTROL KEYS for this display are:
p : Pause the updating of this display
t : Toggles whether planets leave a trail as they move
+ : Zooms in on the Sun
- : Zooms out from the Sun
* : Zooms out from the Sun (x10)
r : Restore Default Zoom value
l : Dump current screen to an IBM compatible printer
(Best results are obtained in EGA Mode)
Jupiter's Moons Display Description
The Jupiter Moon Display shows the position of the four major
moons of Jupiter as they orbit the planet. The view perspective
begins as you would see Jupiter and its moons when looking
through a telescope. Using the UP/DOWN arrow keys the perspec-
tive can be changed. Pressing the UP arrow key moves the perspec-
tive of the observer up from the plane of the moon's orbits
toward the North Pole of Jupiter. Pressing the Down arrow key
moves the observers perspective back down to the plane of moon's
orbit.
In the upper left corner of the screen is displayed the current
simulated width of the screen in Million Kilometers. In the
upper right corner of the screen is the observers angle above the
plane of the moon's orbit. When the Tilt is zero, the display
simulates the view an observer would have from earth. As the
Tilt is increased, the view changes to the view an observer would
have looking down on Jupiter from its North Pole.
By using the control keys you can zoom in toward Jupiter or back
away from it. The 't' key toggles whether the moons leave a
trail as they move.
As in all displays, the Escape key exits from the display.
Note that the time and date displayed at the top of the screen
represents Local Time and assumes system clock is set to daylight
savings time when applicable (see technical notes for more de-
tails on daylight savings time). When 'Leave Trails' is turned
on the time/date displayed on the left is the start time and the
time/date on the right is the current time.
CONTROL KEYS for this display are:
t : Toggles whether moons leave a trail as they move
o : Toggles display of the orbital paths of the moons
+ : Zooms in on Jupiter
- : Zooms out from Jupiter
Up : Move view perspective up towards Jupiter's
North Pole
Down : Move view perspective down towards the plane of
the moon's orbit.
* : Zooms out from Jupiter (x2)
r : Restore Default Zoom value
l : Dump current screen to an IBM compatible printer
(Best results are obtained in EGA Mode)
Planet Size Display
The Size display allows the user to visualize the difference in
size between any two planets, the Sun, Moon and other bodies.
The display draws the two bodies to relative scaled size and
labels them at the bottom of the display. Above each of the
bodies is their diameter in Miles. The figures which appear
between the two bodies show the ratio of the size of the larger
to the smaller one.
Note: If the ratio of size is written in Red, then the size dif-
ference was beyond the resolution of the screen.
Pressing the Esc key will exit the display.
* Refer to Update Mode description of the Setup Time Menu.
Planet Position Display
This screen provides numerical information about the planets, Sun
and Moon's position as viewed from Earth.
The Right Ascension and Declination for each body are given along
with its Altitude and Azimuth.
Each time a key is pressed (excluding the Escape key and the
'A' key) or the Left mouse button is pressed, the display time is
updated according to the Update Mode and the fields are recalcu-
lated and redisplayed.
Pressing the 'A' key or the Right Mouse button will cause the
display to continuously update until another key is pressed.
Pressing the Esc key or pressing the mouse Left and Right button
will exit the display.
* Refer to Update Mode description of the Setup Time Menu.
Planet Distance Display
This screen provides numerical information about the distance of
the planets from the Earth and Sun.
It displays the distance from the Earth to each of the Planets
and the distance from each of the Planets to the Sun. The dis-
tance is measured in Astronomical Units (AUs) and in Millions of
miles.
AUs are equal to 149.6 Million Kilometers or 92.96 Million Miles.
Each time a key is pressed (excluding the Escape key and the
'A' key) or the Left mouse button is pressed, the display time is
updated according to the Update Mode and the fields are recalcu-
lated and redisplayed.
Pressing the 'A' key or the Right Mouse button will cause the
display to continuously update until another key is pressed.
Pressing the Esc key or pressing the mouse Left and Right button
will exit the display.
* Refer to Update Mode description of the Setup Time Menu.
Planet Rise Times Display
This screen provides numerical information about the rise and set
times of the planets, Moon and Sun.
This display shows the rise and set time of each of the planets,
the Sun and the Moon. The Total Rise column gives the amount of
time the body is above the horizon.
The Phase and Apparent Magnitude of each of the bodies are also
listed.
Each time a key is pressed (excluding the Escape key and the
'A' key) or the Left mouse button is pressed, the display time is
updated according to the Update Mode and the fields are recalcu-
lated and redisplayed.
Pressing the 'A' key or the Right Mouse button will cause the
display to continuously update until another key is pressed.
Pressing the Esc key or pressing the mouse Left and Right button
will exit the display.
* Refer to Update Mode description of the Setup Time Menu.
Pick Mode
When in the HORIZON, ZENITH, SKY MAP or ORBITAL (zenith) display
modes, the user has the option of picking an object on the dis-
play to identify it. The object to be identified is selected
using a graphics cursor. If the cursor is positioned within the
capture range of an object, and the Retrn key is pressed, it will
lock on to that object and display information about it. If the
cursor is not within the capture range of an object, the Alti-
tude/Azimuth and Right Ascension/Declination of the location
selected is displayed.
During Pick Mode, the user has the option of outlining the con-
stellations (Asterisms) by pressing the 'o' key. These outlines
can be left on during the 'Picking' process. To turn off the
outlines simply press the 'o' key again.
HOW TO USE THIS FEATURE:
While in a display which supports Pick Mode, press the 'p' key to
enter Pick mode. After all objects on the display have been
updated to reflect the displayed time, Pick Mode will be entered.
Move the cursor around the screen by pressing the arrow keys.
For finer cursor movement press the SHIFT or NUM LOCK key along
with an arrow key. When the cursor is pointing at the desired
object, press the Retrn key to select it. If the cursor is
within the capture range of an object the cursor will first be
repositioned to point at the object. A pop up window will then
appear which will provide details about the object. Depending on
display type being viewed, the following information may be
included:
? Altitude and Azimuth (See Technical notes for definition).
? Right Ascension and Declination.
? Distance from Sun and Earth
? Phase of the object.
? Apparent Magnitude of the object.
? Constellation the object is part of.
? Meaning of Constellation name.
Ie. Orion, "THE HUNTER"
? Name of the object.
? Spectral Type of the object.
? Object Type (Planet,Comet,Star,Double Star,Nebula,etc.).
A Microsoft Compatible Mouse can also be used in pick mode.
While viewing one of the displays that supports pick mode, press-
ing the left mouse button will enter pick mode, just as the 'p'
key does.
Once in pick mode, the mouse can be used to position the pointer
the same way that the arrow keys do. When the pointer has been
positioned to the desired object, the left button of the mouse
can be used to select the object just as the Retrn key will.
Pressing the right button of the mouse while in picked mode, with
nothing currently selected, will exit pick mode the same way the
Escape key will.
Pressing the center mouse button in pick mode will toggle con-
stellation drawing just as the 'o' key does.
Pressing the Left and Right mouse buttons together, while not in
pick mode, will exit the display and return to the main menu.
Find Mode
Find Mode will allow the user to select an object by name. If a
matching name is found among the planets, comets, stars or other
objects, the matching object will be displayed. Pick Mode will
automatically be entered with the cursor preset to point at the
selected object. This feature is available on the Horizon,
Zenith and Sky Map displays.
To use this feature, select the Horizon, Zenith or Sky Map dis-
play from the main menu. A press of the 'f' key will display a
pop-up menu. The name of the object to be located is entered at
the cursor. The entered name may contain letters, numbers and
wild-cards (discussed next). Pressing return accepts the input
name and the search begins. As objects are being search, matches
to the input name are display whenever found. The user is asked
whether this is the object they were looking for. If not, the
search continues. If the object found is correct, the display
boundaries will be adjusted if necessary to display the object.
At this point, Pick Mode will automatically be entered and the
cursor will appear pointing at the selected object. Pick mode
will work the same as previously described at this point. On the
Sky Map display, the display can always be adjusted to display
the matched object. On the Horizon and Zenith displays, the
display direction (or view angle) will only be adjusted if the
object is above the horizon.
Wild-cards are the '*' and the '?' characters. They can be
placed anywhere in the search string when the exact name is not
known. The '*' will match any amount of characters and the '?'
will match any single character.
Say we are looking for the star Betelgeuse in Orion but you're
not quite sure how to spell it. Just enter bet*. Any object
with its name starting with 'bet' followed by any other charac-
ters will be a match. Another example is, you're looking for
messier object M40-something. Enter the search string of m4?.
This will match any three character string with the first two
characters being m4.
Menu Screen Descriptions
This section describes the purpose and function of each of the
menu screens.
The overall layout consists of a main screen which has selections
for each different displays on the upper half.
Along the bottom of the menu are the sub-menu selections. Each
of these allows the default parameters of StarWorks to be 'Tuned'
to fit your specific application.
The Color of the StarWorks menu screens may be altered to suit
your individual taste. The default screen color starts out as
Blue but can be changed per execution by using the '-C' program
call option (see program call options for more details).
The default of Blue can also be changed. Anytime the 'Save
Setup' selection is made, the screen color currently in use
becomes the new default color. Remember, the default screen
color is used anytime the '-C' call option is not present.
Main Menu
The main menu is basically made up of two parts. One
part allows the user to select a display to view.
These graphic and table displays are listed below.
Refer to description of each display type in the
previous sections.
To select one of the following display types, simply
press the corresponding key to the display you wish
to view. Provided that all user entered parameters
from the setup menus are valid, a display will
appear.
If a mouse is active, a block cursor will appear
within the Display Selection boundaries. Position-
ing the block cursor near the display to be selected
and then press the left button. This will have the
same effect and pressing the selection key itself.
Key Display See Page
___ _______ ________
1 Horizon Display pg. 2
2 Zenith Display pg. 3
3 Sky Map Display pg. 4
4 Solar Orbit Display pg. 5
5 Jupiter's Moons Display pg. 7
6 Relative Sizes Display pg. 8
7 Distance Data pg. 8
8 Rise/Set Data pg. 9
9 Position Data pg. 8
I Information for Display Controls
Esc Exit Program
Setup Menus
The second part of the main menu is the Setup Sub-
menu selections. These are found on the bottom two
lines of the main menu. Using these setup menus,
StarWorks can be configured simulate different
events.
To activate one of the setup menus, use the tab or
arrow keys to cause the desired sub-menu box to
blink. Pressing return will then cause a pop up
menu to appear where new parameters can be entered.
If a mouse is installed, pressing the right button
will simulate the TAB key being pressed. Pressing
the left/right button combination will simulate the
RETURN key being pressed.
To change the values in a setup menu, begin by using
the Tab key to position the cursor to the field to
be changed. Enter the new value and press the Return
key. The back space key may be used during value
entry. When all fields are changed as desired, the
Esc key is pressed to return to the Main Menu.
If a mouse is installed, the left and right buttons
can be used instead of the Tab and Esc keys respec-
tively.
If a field in the setup menu was being entered and
the Return key has not yet been pressed, the Esc key
will treat the field as though the Return key had
been pressed before exiting back to the main menu.
The 'Trails' and 'View Direction' setup selections
do not have sub-menus. Instead they toggle/advance
the current value with each press of the Return key.
Time Setup Menu
This menu is used to define the time for which the
display is drawn and to define how much time each
consecutive display is advanced.
UPDATE MODE- If System Clock (0) mode is selected
then the system's clock is used to derive the time
for each consecutive display and the value of Update
Rate is ignored. The value of User Defined time is
also ignored.
Values other than 'System Clock' use the User De-
fined Time described below. Incrementing each
consecutive display is done by adding the Update
Rate to the displayed time according to the display
mode.
A Sidereal Day is one revolution of the Earth with
reference to the stars ( instead of the Sun). It is
approximately equal to 23 hours and 56 minutes.
A Lunar Day is one revolution of the Earth with
reference to the Moon (instead of the Sun). It is
approximately equal to 1 day and 50 minutes.
UPDATE RATE defines how much time is added to each
consecutive display. It is used whenever the 'System
Clock' Update Mode is NOT selected. See Update Mode
definition.
MONTH, DAY, YEAR, HOUR, MIN, SEC are used to set the
User Defined Time. See Update Mode.
* NOTE *: User defined time is specified in
Local Time including Daylight Savings Time when
applicable.
Star Setup Menu
This menu is used to configure how stars will be
displayed when viewing the Horizon, Zenith and Sky
Map displays. Stars can be turned on or off and the
viewable magnitude limits can be adjusted.
DISPLAY STARS selects whether or not stars are
displayed on the Horizon, Zenith and Sky Map dis-
plays (Note: our Sun is not considered to be in the
set of stars but is treated more like a planet)
ENLARGE STARS, If set, brighter stars will be drawn
larger than dimmer stars and comets will be drawn as
a cross. Although this selection creates stars
which are not true to size, it may be helpful for
Non-EGA/VGA monitors which can not show different
star intensities. It may also be useful for creating
more readable printouts on the print device. The
CUTOFF values used for determining intensities are
the same values used to determine plotting size.
FIRST CUTOFF, Stars with magnitudes between minus
infinity and the First Cutoff are displayed in a
high intensity white or largest size.
SECOND CUTOFF, stars with magnitudes between the
first cutoff and the second cutoff are displayed in
a medium intensity white or a medium size.
THIRD CUTOFF, stars with magnitudes between the
second cutoff and the third cutoff are displayed in
a low intensity white or a small size.
Stars with magnitudes dimmer than the third cutoff
are not displayed at all.
For SuperVGA mode, the above is basically still
true. The exception is that star intensities are
displayed in 55 different shades of white instead of
only 3. The intensity of each displayed star/object
is set in accordance with its brightness as propor-
tional to its magnitude. For brightness, only the
value of cutoff3 is important. The brightest star
shade is assigned to the magnitude of the brightest
star loaded from the star file. The dimmest shade
is assigned to stars with magnitudes equal to the
value of cutoff3. The remaining shades are assigned
based on the star's magnitude in respect to this
range. For enlarging stars/objects, all three
cutoff values work as they do in EGA/VGA.
These cutoff values allow the user to limit the
stars displayed, to the stars that can actually be
seen due to the amount of ambient city lights where
they are located.
Planet Setup Menu
This menu is used to select which bodies will appear
on the displays and which bodies will be listed in
the tables. Select 'Yes' to enable the display of
each body and 'No' to disable it.
Location Setup Menu
This menu allows the user to define where they are
located on the planet Earth. This information is
not used in the Orbital or sky map Displays. Nor is
it used on the Planet Distances display.
LONGITUDE is the observer's longitude on Earth.
This value is used in the Horizon and Zenith Dis-
plays and Positions Table. West of the Prime Merid-
ian is positive and East is negative.
Example: Mpls, Mn. is approximately +90
Columbus, Ohio is approx. +80
LATITUDE is the observer's latitude on Earth. North
of the Equator is positive and South is negative.
Example: Mpls, Mn. is approximately +45
Columbus, Ohio is approx. +40
TIME ZONE describes the difference between Greenwich
time and local time.
Example : Central Time is a +6.
Eastern Time is a +5.
New Zealand is in -12.
Trails Setup Selection
LEAVE TRAIL selects whether the bodies on the graph-
ical displays leave a trail behind them as they
move. This is useful for examining the paths they
are following.
View Direction Setup Selection
VIEW DIRECTION is used to select which direction you
are looking when using the Horizon Display. Direc-
tion is the same as it's measured using a magnetic
compass. The full 360 degree circle is broken into
eight directions; North, North East, East, South
East, South, South West, West, and North West.
Zenith View Angle Setup Menu
ZENITH VIEW ANGLE defines the lowest Altitude that
an object can currently be at, and still appear on
the Zenith display. The smaller the value, the
narrower the imaginary cone of view above you will
be. A value of zero provides a fish eye view of the
looking up, including the whole horizon around the
edge of the circle.
Sky Map Window Setup Menu
The values entered here define the location about
which the Sky Map will be centered and how much
Right Ascension will be included between the left
and the right edges of the window.
CENTER (RA) defines the value of right ascension
that the sky map display will begin at.
CENTER (DEC) defines the value of the declination
that the sky map display will begin at.
WIDTH (RA) defines the amount of right ascension
that will be displayed between the left and right
edge of the sky map display.
Save Setup Selection
SAVE MENU SETUP will save the current state of the
menu selections and definitions.
NOTE: The saved menu configuration is read in at
program startup from StarWork.MNU. This will enable
you to set items such as your longitude, latitude
and time zone, then have them come up as the default
every time you run the program.
Example, Go through all the menus setting up the
parameters the way they apply to your specific
situation. Then select the Save Menu Setup option by
moving the flashing-option cursor to the Save Menu
Setup box followed by pressing the Retrn key. A pop
up window will appear confirming the save. From now
on the menus will be setup this way every time you
start the program.
You may also choose to save other menu configura-
tions under different names. When restoring a menu
setup, you may enter the name of any of the saved
configurations.
Restore Setup Selection
RESTORE MENU SETUP will reread the StarWork.MNU file
and reload the default menu setup parameters that
the program starts up with.
When restoring a menu setup, you may also enter the
name of any of the saved configurations. The de-
fault file name will be the name of the last setup
file accessed.
Files used by StarWorks
This section describes the files used by StarWorks. It explains
their usage and where applicable, their format.
STARFILE
This file contains the star data used by StarWorks.
StarWorks will read as many of the stars from
STARFILE as will fit into the available memory on
your system. The chime tone will sound if the
number of stars read in was limited due to lack of
available memory. This file is in binary format and
contains the following information, which can be
seen when an object is PICKED in Pick Mode.
? Right Ascension of the object.
? Declination of the object.
? Magnitude (apparent) of the object.
? Which constellation the object belongs to.
? The name of the object.
? Spectral Type of the object.
? Object Type,
Ie. - Star, Double Star, Nebula, etc.
COMETFIL
This file contains the orbital elements for periodic
comets. The file has the format
field 1: Comet Type (p-periodic , n-nonperiodic
*-comment line)
**** for Periodic Comets ****
field 2: Perihelion Epoch
field 3: Perihelion longitude (degrees)
field 4: Longitude of ascending node (degrees)
field 5: Period (years)
field 6: Semi-major axis of orbit (AU)
field 7: Eccentricity ( only values < 0.98 )
field 8: Inclination of orbit (degrees)
field 9: Name of comet (no spaces, less
than 20 chars)
***** for Non-Period (Parabolic) Comets ****
field 2: Perihelion Epoch data
field 3: Perihelion Distance (AU)
field 4: Argument of Perihelion (degrees)
field 5: Longitude of ascending node (degrees)
field 6: Inclination (degrees)
field 7: Name of comet (no spaces, less
than 20 chars)
Any line with an asterisk (*) in the first column is
treated as a comment line.
*NOTE: ALL fields must be filled in for the particu-
lar comet type. Currently, minimal verification is
performed on the data.
STARWORK.MNU
This is the file used to save the current setup of
the menus. Refer to its definition under the Save
Setup section of the Setup-Menus description.
Every time StarWorks is started, this file is read
(if it exists) and the menu default parameters are
loaded from it. This file is also read to Restore
the default menu parameters on the 'Restore Menu'
option.
Technical Notes
Program Call
After moving to the directory which contains the
StarWorks.exe, starfile. and optional StarWork.MNU
files, the program should be called as follows:
StarWorks {-options}
Where current options are:
s -Do not pause during title display.
n -Do not correct for Daylight Savings Time.
( For Countries which do not use DST )
d -Use European Daylight Savings Time Dates.
A -Use Australian Daylight Savings Time
Dates.
v -Force VGA display mode.
(640x480, 16 colors)
V# -Force SuperVGA display mode.
1 - (640x400, 256 colors)
2 - (640x480, 256 colors)
3 - (800x600, 256 colors)
4 - (1024x768, 256 colors)
** NOTE ** (see CAVEATS section for
notes on SuperVGA modes)
e -Force EGA display mode.
(640x350, 16 colors)
E -Force EGA MONO display mode.
(640x350, 2 colors)
c -Force CGA display mode.
(320x200, 4 colors, palette 1)
m -Force Monochrome display mode.
(640x200, 2 colors)
h -Force Hercules display mode.
(720x348, 2 colors)
l# -Limit the stars loaded into the program
to those whos magnitude is greater
than #.
x# -Limit the Maximum number of stars loaded
from STARFILE to #
C# - Use the color # for menu screens where
1-Blue 2-Green 3-Cyan 4-Red
5-Violet 6-Brown 0-Black
M -Do Not invert the Foreground/Background
colors on sub-menu screens.
P# - Number of passes over the paper when
printing ( default is One )
S# - Selects alternative Symbols/Colors for
Solar bodies.
0 - (default) original StarWorks colors
1 - swaps colors of Sun and Moon
2 - naked eye visual representation
Examples:
StarWork -d -C2
{ Would use European DST correction and
would use Green for the Menu Color }
StarWork -v -n
{ Would turn off DST correction
AND force the program to override
the detected graphics mode and
use VGA graphics display mode
instead.
*** NOTE ***: OPTIONS ARE CASE SENSITIVE.
STARWORKS Environment Variable
If there is an environment variable named StarWorks
set, the program will use its value as the path to
access the files used by the program and you will no
longer have to change to your StarWorks directory
for the StarWorks program to find its files.
As an example, add the line SET
StarWorks=C:\StarWorks to the autoexec.bat file
(assuming the directory c:\StarWorks contains the
StarWorks program and all it's related files).
Reboot your system. Now change to any other
directory, say the root directory. Execute the
StarWorks program (c:\StarWork\StarWork). StarWorks
will still be able to find its working files even
though you are not in the StarWork directory.
GMT Time / Local Time /Daylight Savings Time
StarWorks thinks in terms of Greenwich Mean Time,
but interfaces with the user in their Local Time.
StarWorks uses the value you set in TIME ZONE (see
the Location Menu) to make this correction.
Your system clock should always be set to the cor-
rect local time. This includes daylight savings
time if applicable. If daylight savings time is not
instituted where you are located or you do not want
to set your system's clock in daylight saving time,
StarWorks can be called with the 'n' option. This
will instruct the program not to make any correc-
tions for daylight savings time and will expect the
clock to be set to Local Standard time.
NOTE: Daylight Savings Time is assumed to begin on
the FIRST Sunday in April and end on the LAST Sunday
in October (U.S. DST). European DST (see the 'd'
program call option) is assumed to begin on the LAST
Sunday in March and end on the LAST Sunday in Sep-
tember. Australian DST (see the 'A' program call
option) is assumed to begin on the last Sunday in
October and end on the First Sunday in March.
Phase
The phase of a body is defined as follows:
(using the Moon phases as an example)
0 or 360 degrees is the New Moon.
270 degrees is the first half (Waxing half).
180 degrees is the full Moon.
90 degrees is the last half (Waning half).
This applies to all other solar system bodies.
Altitude and Azimuth
Altitude and Azimuth describe the elevation and
compass direction an object is from the observer.
Altitude is measured in degrees above the horizon.
0.0 is on the horizon and 90.0 is straight up at
zenith. A negative altitude implies that the object
is below the horizon.
Azimuth is measured in degrees from North. 0.0 is
North, 90.0 is East, 180.0 is South and 270.0 is
West.
AU Astronomical Units
Astronomical Units are a measure of length which are
roughly equal to the radius of the Earth's orbit
around the Sun at its farthest point.
1 AU = 149.6 Million kilometers.
Formulas used by the program
The formulas used by this program were derived using
the book 'Practical astronomy with your calculator'
written by Duffet Smith, Peter. Published by Press
Syndicate of the University of Cambridge 1979, 1981.
Development System
This program was written using Turbo-C++ 1.01 on a
Unisys IT with an EGA/VGA display and a 80287.
Program Accuracy
The accuracy of the positions calculated and plotted
vary by a couple of minutes of arc at most. This
will produce plots that are well within the needs of
an amateur astronomer. StarWorks, however, should
not be used for the purpose of Interstellar
Navigation (you may get lost).
Astronomical Experiments
These are just some of the ways you can use
StarWorks to watch the heavens move. Many more are
possible, it's up to your imagination.
* Watch a complete day go by in minutes.
To see the Sun, Moon and the planets traverse the
sky while you watch it a simple task. Load the
predefined setup from fastday.mnu (Use Restore and
enter fastday as the restore file name). Select the
Horizon view and watch.
* Watch the stars circle the North Star as the
Earth rotates through a day.
The North Star is approximately aligned with the
Earth's axis of rotation. If you photograph the
northern sky with long exposures you will get a
picture with the stars forming concentric circles
around the North Star.
To create this picture using StarWorks, simply
restore the predefined menu 'polaris'. Select the
Horizon view and watch.
* Watch the Sun's height in the sky at noon change
through out the year.
As the Earth travels around the Sun, the angle
between an observer on the Earth and the Sun
changes. On the Winter Solstice the Sun is low in
the sky at noon and on the Summer Solstice it reach-
es its high point. To see this you can simply
restore the predefine menu 'sunheigh'. Select the
Horizon view to create the display.
* Watch the movement of the Sun during a Summer
day above the Arctic Circle.
At latitudes above the Arctic Circle the Sun will
not set on the longest day of the year, June 21. To
recreate this 24 hour day, restore the predefined
menu setup 'arctic'. Select the Zenith view and
watch the Sun skirt around the whole horizon without
ever setting.
If you display Planetary Data (from the main menu)
you will notice that the Rise/Set time for the Sun
is "Never Sets."
* Watch the retrograde motion of the planets.
The retrograde motion of the planets refers to the
way they wander through the constellations from
night to night. In fact, the word planet means
wanderer.
To see this motion, simply restore the predefined
menu setup 'retrogra'. Select the Horizon view and
let the screen paint. You will see the planets as
they wander amongst the stars.
* Watch comet Swift-Tuttle nearly strike the Earth.
In approximately March of the year 2128 A.D., comet
Swift-Tuttle will come uncomfortably close to strik-
ing the Earth. To view this occurrence, load the
predefine menu 'tuttle'. Select the Solar Orbits
display and choose the Zenith view. Watch as the
comet nearly strikes the Earth.
Caveats
Since this program was written on an EGA/VGA system,
the displays were optimized to look best in EGA and
VGA modes. Although the program does run in CGA
mode, the display is of lower quality (due to the
low resolution) and is limited in usefulness if any
detail is required.
Since SuperVGA modes tend to be non-standardized,
unpredictable results can occur if a SuperVGA mode
is selected which is not supported by the graphics
adapter. For the same reason, SuperVGA modes are
never selected automatically; they must be forced if
desired.
The program is very math intensive and needs a math
co-processor to run effectively, especially on
systems with slow clock speeds. The program will
run without math co-processor support. However, the
program becomes limited in its display updating
due to the long calculation times of the math emula-
tion routines.
If you have a math co-processor and are interested
in seeing just how slow this program will run with-
out it, do the following.
Before executing StarWorks (at the DOS prompt), type
"set 87=n". The program, when run, will detect this
value and use floating point emulation routines
instead of the math chip.
Now that you have seen what a good investment your
math co-processor is, you can enable it by exiting
StarWorks and typing "set 87=y."
NOTE: The " (Quotes) were not supposed to be typed
in.
Terms of License
As the licensee of the Full Function Version (ex-
clude limited version) of this program, you may use
the program on one computer. If you are an individ-
ual (not a company or an institution), you may use
the program on any other computer(s) that you own
personally. Companies and Institutions must regis-
ter one copy per computer or obtain a site license.
Copyright Notice
If the version number displayed on the first screen
ends with '(Limited),' this version of StarWorks is
being distributed as a Limited Demonstration ver-
sion. Its only limitations are that it will work
for a limited date range and that it includes fewer
stars/objects in the data base. The Full Function
version will work between the years 1700 and 2500.
The full function version also includes over 11,000
stars and messier objects.
Limitations on distribution and use include the
following:
No responsibility for the operation of StarWorks is
assumed or implied by Sci-Vision. The user of
StarWorks uses the program at their own risk. Sci-
Vision assumes no responsibly for damages caused by
use of this program.
This limited version of the program and its documen-
tation may not be distributed if any changes have
been made.
The copyright notice and statement of authorship
must not be modified or removed.
All copies of the Full-Function (Unlimited) version
must be registered and may not be distributed.
LIMITED versions of StarWorks may be distributed for
a nominal fee not to exceed $5.00(US).