home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Fritz: All Fritz
/
All Fritz.zip
/
All Fritz
/
FILES
/
EDUCNOMY
/
ASTRONOM.LZH
/
ASTRONOM.DOC
< prev
next >
Wrap
Text File
|
1988-04-15
|
35KB
|
809 lines
This program is designed to run on the *IBM PC
and 'true' compatibles. It requires at least 256 K of
memory and CGA Graphics capability or equivalent.
Copyright 1987 by Ed & Stewart Vernon. All rights reserved.
Ed Vernon
P.O. Box 61095
Raleigh, N.C. 27661
This Program is made available to be copied and passed
on to others, as long as it is copied in it's entirety and
not altered in any way. It is not Public Domain.
This Program is solely the property of the Author, and
no remuneration may be made for it except to the Author at
the address listed above. Try this program, and if you con-
sider it usefull, or worthwhile, send $20, or whatever you
consider it's worth, to the address listed above. In any
case, pass it on to a friend to evaluate.
This Program may be freely Uploaded and Downloaded to
and from Bulletin Boards, and related public access facil-
ities, as long as no charge is made, and all the Program
is passed-on without change or modification.
*Registered trademark of IBM Corporation.
Page 1
Before Running this program, it is desirable to Enter
the correct Time and Date into your DOS System, as the pro-
gram utilizes this Time and Date initially to establish a
reference. If you would like Graphic Printouts of the star
maps, it will be necessary to also pre-load the Graphics
function that comes with your DOS operating system. Follow
the instructions that came with your system to load, and
actuate the Graphics program.
Page 2
ASTRONOMY
Copyright 1986 by Ed & Stewart Vernon
All Rights Reserved
In general this Astronomy program is intended as an aid
to the Amateur Astronomer or the serious student of Astro-
nomy. It can draw a map of about 900 of the brightest stars
for any time of the day, at any location on the Earth. It
can locate all of the planets, as well as the Sun and Moon,
on this map, or give you a list of their coordinates. It
can outline all the 88 Constellations, and plot the path of
the Sun, Moon, and Planets against the background of Stars.
You can Enlarge any portion of the Starmap, and locate any
point according to astronomical coordinates.
A bit about Stellar Magnitudes
The Greek astronomer Hipparchus first conceived the idea
of dividing all visible stars into six arbitrary grades of
brightness. The brightest group of about 20 stars, were cal-
led first magnitude stars. Later on Ptolemy refined this
method somewhat and introduced fractions of a magnitude.
With the invention of the telescope, many more stars
became observable, and more exact comparisons between stars
were needed. Instead of opinion and guesswork, each magnitude
differed from the next by a factor of 2.512 or about two and
one half times. The difference between five magnitudes being
equivalent to a ratio of 100 to 1.
It was found that some stars were actually brighter than
first magnitude, so the concept of 0, and even minus values
of magnitude was introduced. For instance, Sirius, or Alpha
Canis Majoris, which is the brightest star in the sky is at
magnitude -1.4. Our Sun is magnitude -26.7 and our Moon is
magnitude -12. However, under perfect viewing conditions,
only stars to the sixth magnitude can be visible to the un-
aided eye.
This program contains stars to about magnitude 4.5, so
there are approximately 900 that may displayed. It is impor-
tant to remember that the higher the positive magnitude, the
dimmer the star. Seven different symbols represent stars of
seven different magnitudes. You can change the magnitudes
that correspond to each symbol from it's default value if
you wish. You can also change the lower magnitude limit of
stars drawn on the starmap.
By making the magnitude limit a lower number, correspond-
ing to a brighter star, you decrease the number of stars on
the display, therefore increasing the speed at which the
screen is drawn. This capability is quite practical when you
have to go back and forth between different starmaps and/or
other screens.
Page 3
Program Operation
Before attempting to Run the Astronomy program, the first
thing to do is make a "back-up" copy for general use. Use the
"Diskcopy" function of your computer. Put the original safely
away and run the back-up copy only.
Type ASTRONOM and press the Enter key. You should get a
Title screen, which tells you to wait while the program Data
is being loaded.
Generally, Upper and Lower case does not matter, and
input functions for the most part are automatically limited
by the Computer to the proper type and length. One case in
particular where the input is not limited, is the Star Magni-
tude Breakpoints. Since Magnitude values may be + or -, and
different decimal values over a broad range, these numbers
are not limited. You could possibly limit your Star Presen-
tation to Zero Stars, by choosing extreme values here.
After the Program has fully loaded, the first screen to
appear is the Title Screen showing Local Co-ordinates, with
an Option to Change. If 'C' to Change is pressed, the program
will ask if you know your Longitude and Latitude. If 'N' for
no is pressed, a World Map will be drawn. If any key other
than 'N' is pressed, you will be asked to Enter each Local
value at the prompts. If you don't know your Time Zone, 'O'
for Other may be used for any location. Upon completion you
will be asked to press 'S' to save Local Co-ordinates on
disk, or any other key for Temporary use.
If you selected 'N' you will get a World Map which is
Cylindrical Orthomorphic, or Mercator, after the 16th Century
Cartographer who invented the style. The sizes of land masses
at the Poles of the Earth are exaggerated to keep longitude
lines parallel.
On PC type Keyboards...
Arrow keys locate the crosshair, which initially appears at
the approximate center of the screen. Holding Shift and pres-
sing the arrow keys will move the crosshair more rapidly.
On the Tandy 1000...
Engaging 'Num-Lock', then using 8,6,2 & 4 on the numeric pad
as up, right, down & left respectively, will facilitate the
rapid crosshair movement.
Press Enter when you are finished, and the screen will
display the correct values of your chosen Longitude and Lati-
tude, and wait for you to press a key. You then choose to
save these values on Diskette, or just have them for tempor-
ary use during this program run.
Page 4
FUNCTION MENU
The next Screen is the Function Menu, where you would
have already arrived if you had not chosen to change the lo-
cal coordinates. This is the Main screen, and is where the
program generally returns you after each function is complet-
ed. Pressing a Single Key actuates the indicated Function. A
real-time clock is situated above the Menu for convenience.
The Function Menu Screen looks something like the following;
Astronomical Ephemeris and Planetarium
(C) 1987 by Ed & Stewart Vernon
All Rights Reserved
(Real-Time Displayed here)
F U N C T I O N M E N U
A lter the local co-ordinates
C hange graphics color sets 1
S et-up magnitude breakpoints
U pdate current time and date
D aylite saving toggle on/off
L ocate one particular planet
M ap of visible stars plotted
P lot daily planetary motions
O utlining the constellations
Q uit program & return to dos
Current Date is Displayed here
If Daylite saving time, it is indicated here
Pressing the first key in the line (which is hilited)
actuates the given function. Any other key will have no ef-
fect except to redraw the Menu screen.
Page 5
Function MENU
There are 10 Keys that perform a Function on this Screen.
These Keys at the start of each line, are Hi-lited for empha-
sis. You do not have to press the Enter key.
The Hi-Lited Keys Function as follows:
A - Alters the Local Coordinates.
Current Local Stats are displayed on the screen, with a
press 'C' to change capability. This is the same as the
Initial screen you are greeted with.
C - Change Graphics Color Sets.
Will allow the user to select between 4 color sets for
the graphics displays. The number of the current set is
displayed on the Menu Screen.
S - Set-Up Star Magnitude Breakpoints.
Will list the graphic symbol for stars less than each
given Magnitude, for 7 different levels, and the lower
limit of magnitude for display on screen. The initial
lower limit is 5, and all 900 or so stars in memory will
be displayed.
Press 'C' to change, or any other to return to menu is
displayed. After pressing 'C' you may press 'R' to Reset
all magnitudes to their original values, or press any
other key to Enter New Magnitude values. Pressing any key
other than 'R' will place the '<' cursor at each value to
Enter. Enter a value, or just press Enter to keep the
current one. The same applies to the magnitude lower lim-
it.
Making the magnitude lower limit smaller will display
fewer stars on the screen, but the Starmap will be fin-
ished sooner. There is therefore a trade-off between how
thorough you wish the map, and how rapid you wish the
display. For various reasons you may desire to go back
and forth between several displays, and speed would then
be important. After many times of this, you may then wish
to display all the stars for a final judgement, or per
haps for a Graphic Screen Dump.
The actual speeds will depend on your particular Com-
puter configuration. For instance, on the Tandy 1000 it
takes 1 minute and 58 seconds to draw the complete star
map, while on the PC AT, it takes 42 seconds. If you set
a magnitude lower limit of 3, the Tandy 1000 takes 22
seconds to display, while the PC AT takes 8 seconds.
Page 6
FUNCTION MENU (Cont)
U - Update Time and Date.
The current Time & Date are Updated from DOS and printed
at the bottom of the Menu. The real-time clock above
keeps the current time constantly, but the Time and Date
at the bottom of the Menu are the 'Active' ones for Menu
Functions. The Function Time and Date stay the same until
you change them, in case you wish to repeat the same.
D - Daylight Saving Time Toggle on and off.
You may want a starmap of a date before Daylight Saving
Time was conceived, or of an uncertain period. When act-
ive the time is automatically compensated to allow for
Daylight saving time. Pressing this also Updates the
Function Time and Date.
L - Locate a Particular Planet.
This is the Ephemeris Function. The Planets, Sun and Moon
are numerically listed for you to select one. If you just
press Enter, the Sun is selected. You may then have the
option of changing the Date and Time. The Time and Date
will remain the same for all functions, unless you change
them at an opportunity such as this, or Update from the
Menu Mode. The Planet is then located, and it's distance
from the Sun is printed, as well as it's rise and set
times.
If the selection is the Moon, no distance from the Sun
is displayed, but the phase is indicated.
Remember that a Planet or the Moon may actually rise
in the evening or night, and set in the morning. You must
then either interpret the set time as the following day,
or the rise time as the previous day.
M - Map of the Stars is Drawn.
You first get the opportunity to change the Date and the
Time. Then the Star Map is displayed according to the
established magnitude breakpoints and magnitude lower
limit you have previously set, or to the default values.
The Date & Time is displayed in the upper left of the
screen.
While the Starmap is displayed you may press 'F' to get
a list of the sub-functions available only from the
Starmap Display Mode.
Page 7
Sub-Functions from the Starmap Mode
D: Displays Date and Time in the Upper left Corner.
K: Writes Longitude and Latitude in Upper right Corner.
C: Draws Compass Points, N,S,E and W on Screen.
Z: A crosshair is drawn across the sky directly overhead
locating the Zenith.
E: Draws the Celestial Equator.
S: Draws the Ecliptic, or apparent path of the Sun.
P: Draws the Planets, Sun and Moon on the Starmap.
1-9 Draws Circles of N * 10 degrees from the Zenith.
( where N is the number pressed )
B: Lists Magnitude Breakpoints at the left side.
L: Locates points on the Map in RIGHT ASCENSION and
DECLINATION. Press 'L' and a crosshair appears approx
in the center of the screen, with the right ascension
& declination printed at the lower left. The crosshair
may be moved by the arrow keys. When you are through
with this Function, just press Enter.
M: Magnifies an area of your choosing to fill the entire
screen. As with 'L', a crosshair appears at the center
and can be located with the arrow keys. This time no
values for right ascension & declination are displayed
on the screen.
Locate the crosshair to one of the corners of the
area you wish to enlarge, and press the Enter Key. A
Full-Length Vertical & Horizontal line crossing at
your reference point will appear on the screen, and
the crosshair will re-locate back to the center. Now
re-position the crosshair to be diagonally opposite
from your first choice to form the total area you
wish to magnify and again press Enter. Another Vert.
& Horiz. line will appear, and a rectangle will
outline the selected area.
While the Rectangle is on the screen you may press
'K' and reset the magnitude breakpoints and magnitude
lower limit. Otherwise, just press Enter and the Star
map will be re-drawn magnified to your scale, and the
word Magnification will appear at the top when the
display is complete.
While in the Magnification Mode, pressing 'R' will
return to the original 'Full-size' Starmap. Pressing
Enter will return to the Function Menu.
N: In the Regular Mode or Magnify Mode, pressing 'N'
erases the bottom line of the screen. (In case the
name of a constellation is written there ...also see
'O' Sub-Function.)
F: Functions Display. ( This Screen )
Page 8
Sub-Functions (Cont)
R: Redo Screen and Redraw Starmap. The original Starmap
is redrawn without the Date and Time, erasing all of
the writing, Planets, and Cursors. However, when you
select 'F' from the Starmap Mode to view these
functions, whatever is on the screen at the time will
become the new 'Redo' screen. Thus if you want the
Redo screen to remain as the original Starmap, always
press 'R' before pressing 'F' while in the Starmap
Mode.
O: Outline Constellations on the Current Starmap. Press
'O' from the Starmap Mode and get the list of all 88
Constellations to select from. You must enter the name
of one, spelled correctly, but upper or lower case is
unimportant. After typing the name and pressing Enter
you will return to the Starmap screen and the selected
constellation will be outlined by it's Official
Boundaries, if it is located on the screen at this
time. If all or part is off the screen, the words
'Plots Beyond Horizon' will appear in the upper right.
You may repeat this function as many times as you
like, with the previous constellations staying on the
screen. The most recent constellation drawn will be
named at the bottom of the screen. Pressing 'N' in
the Starmap Mode will erase this name. Magnify can be
selected, and Magnified Constellations may be drawn.
While in the Plotting Mode Only, pressing 'A' allows the
track of a second Planet to be plotted on the first in a
different color. The same Date and Time, and length of Plot
will be used for both Planets, however.
In the Constellation Mode Only ... This is the Constellation
Mode selected from the Main Menu, not from the Starmap Mode:
N: Writes the Constellation name at bottom of screen.
T: Writes Time the Constellation is at it's Zenith in the
upper left corner of the screen.
Pressing Enter leaves the Starmap & returns to the Main Menu.
Page 9
MAIN MENU FUNCTIONS (Cont)
P - Plots of Daily Planetary Motion.
Pressing 'P' reveals a short explanation, and an oppor-
tunity to abort if accidentally selected. Pressing 'P'
again gives you the chance to change the Date and Time.
The current Date is the first day of the Plot, and you
are required to enter the number of days you want the
plot to run. You must enter a value from 1 to 365. Then
the Planets are listed for you to select from. Pressing
a number then allows the Starmap to be drawn for the Day
and Time of the first Plot. The upper left of the screen
displays how many days, and which Planet you're plotting.
The first plot will be a + sign, and all other plots
will be small circles. The lower left portion of the
screen displays the start and end Dates. As the plots are
being calculated, the current plot number is also shown
for your reference. It will be erased when the last plot
is made. Pressing 'A' after the plot will allow you to
plot another on top of the first. The Planets are again
listed for your choice, then the second Planet is plotted
in a different color. The name of the second Planet is
printed in the upper right and the Dates in the lower
right. Pressing any key will then return to the Menu.
If 'A' is not selected, pressing any other key twice will
return to the Main Menu.
O - Outline a Particular Constellation.
Pressing 'O' gives you a list of all 88 Constellations
visible in the entire sky. You must enter a constellation
name, spelled correctly, although upper or lower case
doesn't matter. After typing the name and pressing Enter
you get a chance to change the Date. Then the Time at
Zenith, or the time the constellation is directly over
head on this Date, is listed on the screen. You may then
choose 'R' to repeat for another constellation, or 'M'
to return to the Main Menu, or any other key to display
your selected constellation. The constellation will be
drawn as it will look when directly overhead, as the
entire Starmap is now reset for this Time.
Other constellations may be outlined on this map by
selecting 'O' after the original outline is finished, but
while the Starmap is still on the screen. Press Enter to
return to the Main Menu.
Copyright 1987 by Ed & Stewart Vernon
All Rights Reserved
Page 10
Operational Hints
The Zodiac signs do not exactly correspond to their
counterparts in the 88 Constellations. That is to say, the
Zodiac signs do not occupy the same space as the constella-
tions of the same name. The Zodiac divides the sky circle
into 12 equal parts, each one being a sign taking the name
of a constellation. The actual path of the Sun through the
actual constellations is considerably different. It is al-
most twice as long in Taurus as it is in Aries. However,
for approximation, they can be used interchangably for the
purposes of locating the Planets.
If you wish to find a given Planet, say Jupiter, for
instance, on some future date, such as April 17, in the
year 2000. Use the Locate Planet Function, and set the
proper date. Select the planet Jupiter, and for an Eastern
United States location the screen indicates it will be 12
degrees in the Constellation Taurus along the Zodiac. Now
go back to the Menu by pressing any key. Press O for out-
lining the Constellations, and leave the date as is. When
the screen lists the constellations, type in Taurus and
press Enter. Leave the date as 4-17-2000, and the screen
will indicate that on this date the constellation Taurus
will be directly overhead at 10:16 in the morning.
Return to the Main Menu and press M for Starmap to be
drawn. Leave the date as 4-17-2000, and the time as 10:16
A.M., and after the map is finished, press P to draw the
planets on the screen. You will need to watch while the
planets are initially drawn, as some of them will over-
write each other due to their relative closeness on the
screen. You will find the Planet Jupiter is slightly out-
side the actual constellation of Taurus, in Aries. How-
ever, it is very close, and enabled it to be easily lo-
cated.
You can press O while this same screen is still on,
and select Taurus to be outlined, and you can verify
Jupiter is slightly to the right, in the constellation
Aries. Press O again and select Aries to be outlined,
and you have more proof.
The Planets will often "over-write" each other as
they are drawn on the screen, due to the closeness. You
need to watch carefully as they are drawn, and there is
always enough time between planets to recognize where
each is located.
Page 11
If the Planets had moved in nice smooth arcs across
the sky, the ancient astronomers would have had little
difficulty in devising a workable theory. Folks such as
Ptolemy, Kepler, and Copernicus would have found it easy
to describe the planetary motion mathematically. As it
turns out in real life however, the planets do strange
loop-the-loops, often going completely backward in the
sky as they wander about.
Of course, nowadays it is commonly known that the
planets actually orbit the Sun in ellipses, and that
their orbits are sometimes above, and sometimes below
the plane of Suns apparent orbit. Also the inner planets
move faster than the outer, and as the inner ones catch
and pass the Earth, or the Earth catches and passes the
outer, apparent reverse motion is observed.
This loop-the-loop behavior is not readily observa-
ble unless one watches over an extended period of time.
Therefore most observers these days don't even notice
what gave the ancient philosophers such a hard time.
The Plotting Function enables you to observe this
odd planetary behavior in a realistic way, without hav-
ing to spend long nights out in the weather. Just press
P from the Main Menu, then press P again when the veri-
fication message comes on the screen.
Select the Date of September 1, 1986, at 3:00 in
the afternoon. Then choose 120 days as the time period.
Now select the planet Venus, and watch as the starmap
is first plotted, then the path of Venus over the 120-
day period beginning with 9,1,1986 is plotted. The star
map stands still while this is plotted, but this is a
matter of practicality in presentation. In reality, of
course, the stars would shift to the right each night,
as the planet shifted to the left. For simplicity the
stars are held still while planets path is plotted a-
gainst their backdrop, the relative location between
the two being accurate just the same. The time of 3:00
is accurate only for the first day, however.
Notice the loop path formed as Venus appears to
stop, back up, and curve upward then continue on it's
forward motion. If you now press A, you can plot an-
other planet's path on top of the path of Venus. You
must use the same date and time, but you should now
choose the Planet Mercury. Watch as the path of Mer-
cury is plotted in a different color, and covers a
longer distance for the same time period. For this
period the path of Mercury forms a sort of Z as it
does a double loop.
Page 12
When in the starmap mode and you press either the
sub-function E for the Celestial Equator or S for the
Ecliptic, the screen may appear to pause for a while.
This is a normal occurrence, and is no reason to be
alarmed. Both these curves are plotted on the screen
referenced to the first point in Aries. As they pass
off the screen to the left, or even start off to the
left, the data must be "chewed-up" to again start at
the right side of the screen. This "chewing-up" takes
a few seconds, and the screen appears to pause.
RIGHT ASCENSION is the celestial equivalent to Longi-
tude, and is measured in Hours, Minutes and Seconds,
starting at the first point in Aries.
DECLINATION is the celestial equivalent to Latitude,
and is measured in Degrees North or South of the
celestial Equator.
The CELESTIAL EQUATOR is simply the Earth's Equator
projected on to the celestial sphere overhead.
SIDEREAL TIME is the time reckoned according to the
sphere of the stars, or startime. The sidereal time
is the difference between the first point of Aries
and the observer's longitude projected into the
sphere of the heavens.
The ECLIPTIC is the approximate path of the Sun thru
the celestial sphere. All the planets and the Moon,
follow this path fairly closely.
ZENITH is the point in the sky directly overhead.
The FIRST POINT of ARIES is the position of the Sun
as it crosses over the celestial equator at the
time of the Vernal (Spring) Equinox.
LONGITUDE is measured in Degrees East or West of a
line passing through Greenwich England and the Poles
of the Earth. (Max 180 Deg)
LATITUDE is measured in Degrees North or South of
the Earth's Equator. (Max 90 Deg)
Page 13
FUNCTIONS AVAILABLE FROM THE STARMAP SCREEN
D - Date and Time in the upper left corner of the screen
K - Longitude and Latitude printed in upper right
C - Compass points N, S, E, and W drawn on the screen
Z - Zenith cursor, lines North to South & East to West
E - Draws celestial equator on the screen
S - Draws the path of the ecliptic on the screen
P - Draws the Planets, Sun and Moon on the screen
1-9 Circles N * 10 degrees from Zenith are drawn
B - Lists Mag breakpoints at the left side of the screen
L - Locate points in Right Ascension and Declination
M - Magnify an area of the screen
N - Erases the bottom line of the screen
F - Functions Display ( This set of Fumctions )
R - Redraw original starmap screen
O - Outline Constellation on this starmap
In Plotting Mode Only
A - Plots another Planet, Sun or Moon on the same screen
In Constellation Mode
N - Prints Constellation Name at the bottom of screen
T - Time Constellation at Zenith printed in Upper Left
(C) 1987 by Ed & Stewart Vernon
All Rights Reserved
Page 14
INDEX
Item Page
-------------------------------------------------------------
"back-up" ................................................. 4
Alters the Local Coordinates .............................. 6
Change Graphics Color Sets ................................ 6
Constellation ............................................ 10
Daylight Saving Time Toggle on and off .................... 7
DECLINATION ............................................... 8
Ephemeris ................................................. 7
FUNCTION MENU ............................................. 5
Hipparchus ................................................ 3
Locate a Particular Planet ................................ 7
Magnification ............................................. 8
Magnitudes ............................................. 3, 6
Map of the Stars .......................................... 7
Operation ................................................. 4
Operational Hints ........................................ 11
Outline a Particular Constellation ....................... 10
Outline Constellations .................................... 9
Plots of Daily Planetary Motion .......................... 10
Ptolemy ................................................... 3
Redo ...................................................... 9
RIGHT ASCENSION ........................................... 8
Set-Up Star Magnitude Breakpoints ......................... 6
Starmap ................................................... 7
Sub-Functions from the Starmap Mode ....................... 8
Update Time and Date ...................................... 7
Zodiac ................................................... 11
