Jason Aller Floppy Collection/219.img/DEPSPAC1.ZIP/README.DOC

Text File | 1987-08-11 | 26KB | 569 lines

<                                  ORDER FORM
<
<(Make checks payable to David Chandler Co., P.O. Box 309, La Verne, CA 91750)
<
<    Registered Copy of DEEP SPACE                         $49   __________
<      (Comes with a copy of THE NIGHT SKY and
<       EXPLORING THE NIGHT SKY WITH BINOCULARS)
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<    3-D Viewer Kit (Purchased with Resistered copy        $10   __________
<       of DEEP SPACE)
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<    3-D Viewer Kit (Purchased separately)                 $25   __________
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<    Unregistered Copy of DEEP SPACE                       $15   __________
<      (For evaluation purposes only.  Comes with coupon
<       for $15 off registration price.)
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                                  QUICKSTART

Type:

  README   to print or list this documentation file
  CONFIG   to specify your system configuration on first startup
  DS       to run DEEP SPACE (fast version--only with 8087 math co-processor)
  DSS      to run DEEP SPACE (SLOW version without 8087 math co-processor)
  PLANETS  to run PLANETS (no 8087 chip needed)

  (The second disk has six files containing data on 18,000 stars.)

DO NOT DELETE ANY OF THE PROGRAMS FROM THE DISTRIBUTION DISK.  AS YOU COPY
THE PROGRAMS AND DISTRIBUTE THEM TO YOUR FRIENDS AND COLLEAGUES, PLEASE COPY
ONLY COMPLETE, UNALTERED DISK PAIRS.

When in doubt type <ENTER> for a default or <ESC> to exit.  These work many
if not most places.  It is recommended that you run the programs after a
fresh re-boot.  Strange things can sometimes happen otherwise.  The programs
need a minimum of 512k of memory.
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                                   FEATURES

     Two clusters of programs are included here.  DEEP SPACE and PLANETS.
The most unique feature of DEEP SPACE is its ability to produce pairs of star
maps which show up in true 3-D when viewed with a special 3-D viewer which is
available upon registration of the program.  The path of any comet can also
be seen in vivid 3-D, swooping in from the distance and returning to the
depths of space, either as seen from the earth or from any chosen vantage
point in space.  This is real data you are seeing: real star distances and
real orbits of real comets, either known already or newly discovered!
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DEEP SPACE also allows you to do all of the following and more:

    Plot accurate custom star maps, either flat or in 3-D
     ... for any part of the sky, to any scale
     ... for any given day, time and latitude
     ... with or without constellation lines drawn in
     ... with or without labels
     ... in your choice of projection system
     ... to any brightness cutoff down to magnitude 7.2

    Compute an ephemeris (an observing schedule) for any comet that is
    discovered, and plot an accurate finder chart.
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PLANETS allows you to:

    Plot a planet finder chart for an entire year as seen from earth.

    Plot planet orbits as seen from space.

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For the convenience of teachers, both parts of the program can be plotted for
either the calendar year or a school year.
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                         Configuration Considerations


HOW TO ...

... get started

     The first thing you need to do is run the configuration program by
typing: CONFIG.  This sets up a file called CONFIG.DAT that tells the program
how many disk drives, the kind of graphics card and monitor you have, and
whether you have an 8087 math co-processor.  After configuring, type DS if
you have an 8087 math co-processor or DSS (ie. DEEP SPACE--SLOW!) if you
don't.
>
|HOW TO ...

... use different numbers and types of disk drives

     The configuration program gives the options of using a single floppy
drive, two floppy drives, or a hard disk drive.  In particular, note that on
a hard disk, all files from both the data and program disks must reside in
the same directory.

... configure for video board and monitor

     In its present form DEEP SPACE requires a CGA board (Color Graphics
Adaptor) if graphics are to be seen on the screen, whether or not a color
monitor is used.  If you do not have a CGA board you can still use DEEP SPACE
in non-screen-graphics mode.  The printouts are not dependent on the screen
display.  The only limitation in printed output is that you cannot get
constellation labels or other text on the star maps, since these must be
placed interactively while seeing the screen graphics.
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|HOW TO ...

... configure for 8087 math co-processor

     DEEP SPACE should ideally run on a computer with an 8087 (or equivalent)
math co-processor.  This is because it uses rather heavy "number crunching"
in its routines.  There are 18,000 stars in the file.  Processing time really
adds up!  The 8087 version can print a star map about 5.5 times as fast as
the non-8087 version.  Still, you can get the same final results without the
8087 if you are very patient.  You might want to take up meditation to help
you through the slow parts, especially in the star mapping routines.
>
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                              Star Map Features

HOW TO ...

... plot star maps

     At the main menu, choose the star mapping option.  You will then be
presented with three options.  Options 1 and 2 are easy to use.  To take full
advantage of option 3 you must know a little more about the sky.

... plot a star map for the given day and time

     The first option asks for the day, time, latitude, and magnitude cutoff.
Day and time are easy.  You can find your own latitude in an atlas, or  be
adventuresome and choose some other part of the world.
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|HOW TO ...

... plot more or fewer stars on your map

     The brightness of a star is its "magnitude".  First magnitude refers to
the brightest stars.  Sixth magnitude is as faint as most people can see with
unaided eyes.  The stars in the data file go down to about magnitude 7.2
(18,000 stars).  You will want to limit your maps to about magnitude 4 or 5
if you show the whole sky, or they will look too cluttered.  If you are
selecting a smaller area, going fainter makes sense.
>
|HOW TO ...

... plot a star map for a given part of the sky

     You can select any part of the sky with map options 2 or 3.  Option 2
decides the scale and projection for you and eliminates options you may not
understand if you are a beginner.  You choose the part of the sky by
selecting a constellation.  Option 4 prints out a list of constellations with
their abbreviations.
     Option 3 gives maximum flexibility, but assumes a little more knowledge.
If you are a beginner, you can get through option 3 by typing <ENTER> to
select the default for options you don't understand.
     Coordinates may be unfamiliar to you.  If you select Equatorial
Coordinates, a position in the sky can be selected either by constellation or
by numbers.  In equatorial coordinates R.A. (Right Ascension) measures around
the equator like longitude on the earth, except R.A. is measured in hours
instead of degrees (24 hours is a full circle).  Dec. (Declination) measures
north or south of the equator in degrees just like latitude.  The North and
South poles are +90 and -90 degrees, and the equator is 0 degrees.
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|(cont.)
     Ecliptic coordinates are most useful when studying motions of objects in
our solar system.  They are related to the plane of the solar system.
Similarly, galactic coordinates are based on the plane of the Milky Way and
will be of most interest when galaxies, nebulae, and star clusters are added
in a future release.
     One of the extras that comes with registering DEEP SPACE is a printed
star dial called THE NIGHT SKY.  Besides being a handy aid for identifying
constellations at night, it can be used to look up coordinates.  R.A. is
marked along the equator.  Declination is marked along the radial lines.
     The projections are a fine point.  They are like projections of earth
maps.  Since the sky appears to be a sphere the idea is to try to flatten it
out with as little distortion as possible.  For small areas of the sky any of
the projections will work fine.  For larger areas distortion is of more
concern.  Stereographic and Mercator projections distort sizes more than
shapes: Stereographic exaggerates sizes far from the center, Mercator
exaggerates sizes far from a center line.  A Gnomonic projection is like a
photograph, again best at the center.  Polar Equidistant stretches the east-
west dimension far from the center.
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|HOW TO ...

... plot a 3-D star map

     We see 3-D in everyday life because we have two eyes that see the world
from two different points of view and act like built in range finders.  The
reason we don't see depth in the sky is because the sun, moon, and stars are
all so far away.  We can put 3-D back into the view if we exaggerate the
separation of our eyes and calculate where the stars would appear from those
points of view.  The farther apart you place your eyes the more depth there
will be.  In order to see 3-D you need a special viewer so each eye sees a
different view of the universe.
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|HOW TO ...

... identify individual stars on a star map

     Once a star map is plotted on the screen you can identify any star by
using function key F2 to bring up a cursor, and using the arrow keys to move
it around.  Holding the shift key down with the arrow keys makes the cursor
take larger steps.  Typing the <Enter> key when the cursor is centered
exactly on a star will bring up an identification at the top of the screen.
Typing any key will clear it.

... connect the constellations to see the patterns

     The F4 key causes the constellation lines to be drawn on a finished star
map.  The whole constellations will be drawn whether or not all the stars are
present.  Most of the stars making up the constellation patterns are brighter
than magnitude 4.5, but there are a few that are about 5th magnitude.
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|HOW TO ...

... label the constellations on a star map

     Typing the F5 key causes the program to enter constellation labeling
mode.  A three letter abbreviation for a constellation will show up at the
top left corner of the screen and a blinking cursor will jump to the
brightest star in that constellation.  Place the cursor wherever you want,
hopefully somewhere near the constellation and not overriding the lines or
stars.  The cursor marks the top left hand corner of the name.  Type <Enter>
and the name will plop down and the cursor will jump to the next
constellation.  Continue the process, typing the space bar to skip any
constellation, until the process is finished.  Typing <ESC> will abort the
process.
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|HOW TO ...

... redraw / zoom

     Any star map may be redrawn using the F7 key, with options to retain or
omit any of the overlays, such as lines, labels, or comet paths.  Labels may
not only be omitted, but deleted to allow the labeling process to be
repeated. Anything that is omitted may be regained by typing F7 again.
     If you opt for a whole sky view or the North-South printout format in
option 3, the stars will look rather crowded on the screen.  F7 followed by
the up or down arrow keys will allow you to zoom to either the top or bottom
portion of the map.  The scale of the zoomed map will be approximately the
same as the printed output, depending on the size of your monitor, of course.
You can return to the original size by typing F7 followed by the <Home> key.
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|HOW TO ...

... print out a star map

     F3 will print out beautiful star maps if you have an IBM or Epson
compatible graphics printer.  If you have a dot matrix printer and
the print feature will not work properly, please send in a copy of the
graphics instructions for your printer.
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                                Comet Features

HOW TO ...

... find orbital data on new comets

     A number of comets are already entered in a file, as you will see when
you try out the comet option.  You are not limited to these.  You can compute
the positions of new comets as they are discovered, both to get accurate
finder charts and, using the 3-D graphing capability, to gain an intuitive
grasp of how they are moving through space.
     Six numbers are used to determine the motion of a comet.  These are
called its orbital elements.  Whenever a comet is discovered astronomers at
the Smithsonian Astrophysical Observatory and elsewhere compute these six
numbers from observations.  When you enter those six numbers DEEP SPACE can
compute an "ephemeris", a timetable of when and where it will appear in the
sky.
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|(cont.)
     The most interesting comets are the ones we haven't discovered yet!
Many comets come near the sun only once every million years or so.  With less
exposure to the heat of the sun, they tend to be bigger and give a better
display.  Comets are essentially ice and dust.  They evaporate to form their
tails when they come near the sun, but that also makes them wear out.
     So where do you get the numbers to plug in?  As new comets are
discovered you can ask at your local planetarium, but only exceptionally
bright comets gain the attention of the mass media.  If you want to keep up
on all the comets that are discovered you can subscribe to various comet news
services.  (Try Comet News Service, McDonnell Planetarium, St. Louis, MO
63110.)
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|HOW TO ...

... enter comet orbit data into the program

     The six orbital elements have funny names and symbols.  Two give the
size and shape of the orbit, three are angles that tell the orientation of
the orbit in space, and one is the time the comet is closest in the sun.  You
don't need to know more about them to use the program.  Either ignore them or
read up on them in an astronomy text.  All you have to do is figure out which
is which and type them in.
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|HOW TO ...

... understand the information given in the printout

     The printout shows the range of dates down the left side of the page.
  R.A. & Dec --position in the sky
  R          --distance from sun to comet
  Delta      --distance from earth to comet
  Elong.     --elongation, angle from sun to comet seen from earth
  Phase      --for a comet this tells to what extent the tail points away
               from us (the tail points away from the sun)
  PA         --position angle, the angle counterclockwise from north that the
               tail appears to extend from the comet
  ---------
  Mag.       --depending on the information you type in, the printout may
               have an estimate of the magnitude (emphasis on estimate!)
>
|HOW TO ...

... plot a comet finder chart

     The real beauty of this comet ephemeris is that you can save a file of
comet positions and access it from the star mapping routine.  The custom star
map option of the mapping routine can plot a comet path along with an
"artificial" tail.  The tail is artificial in the sense that it is of fixed
length (0.1 A.U., ie. 1/10 of the distance from the earth to the sun). Since
the length of the artificial tail is not changing, only the angle of our line
of sight and the distance of the comet cause the artificial tail to change
its apparent size.  A comet is actually like a big chunk of ice.  The tail of
a real comet will be virtually nonexistent when it is far from the sun.  As
it warms up coming into the inner solar system the ice evaporates (sublimes)
and the dust blows away, often causing a tail to grow, sometimes much longer
than 0.1 A.U.
     A finder chart and a pair of binoculars is frequently all you need to
see a "bright" comet.  Comets with short periods, on the other hand, have
passed near the sun so often that most of their ice has evaporated and blown
away.  These comets usually have little or no tail and may require a
telescope to see.
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|HOW TO ...

... plot a comet path as seen from earth in 3-D

     If you choose the 3-D option for a star map that contains a comet path a
different heading will appear.  Since comets are very local compared with the
stars, comets and stars can't both be seen in 3-D at once.  The comet path
will look 3-D and the stars will be flat in the distance.  The eye spacing is
now given in A.U.'s (Astronomical Units) rather than Light Years.  One A.U.
is the distance from the earth to the sun.
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|HOW TO ...

... visualize the orbit of a comet relative to earth's orbit

     First, a practical consideration: if you want to visualize the orbit of
a comet relative to the earth's orbit, it is best to run an ephemeris for a
period of at least a year.  The defaults in the program will compute 146
points at whatever interval you choose.  That would be two years at 5 day
intervals or 4 years at 10 day intervals.  The locations of the comet and the
earth when the comet is nearest the sun (called the perihelion point) are
marked.  The mapping routine limits itself to the first 166 positions in this
mode due to memory limitations.  If you want to see a larger portion of the
comet orbit, make the spacing between points larger to keep the total under
166.
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     If you plot comet paths on star maps as seen from the earth, you may
be puzzled by the complicated apparent motions.  The complication is that the
comet is being viewed from a moving platform, the earth.  The earth-based
view is necessary for finder charts because most of us are stuck on this
planet for life.  The view from space, however, makes things clearer.
     To separate the path of the comet from the path of the earth, choose the
option to view the comet from a fixed point in space.  You will be asked how
far from the sun you would like to position yourself measured in A.U.'s.  The
viewing direction will be determined by what part of the sky you have chosen
to look toward.  Your position is chosen so that the sun will be in the
center of the field lined up with your chosen part of the sky.
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     Now the different coordinate systems show their colors.  The Equatorial
system is tied to the equator of the earth, which seems quite natural as long
as we stay on earth.  Once we leave the earth tying ourselves to the earth's
equator is silly.  For solar system objects the Ecliptic system is more
natural.  The "Ecliptic Plane" is the plane of the earth's orbit around the
sun.  If you pick a fixed viewing point in space for looking at a comet
orbit, the earth's orbit will appear horizontal if you choose to view it in
the Ecliptic system.  Since the coordinates you specify are the coordinates
you are looking toward, a latitude of -90 will put you directly above the
solar system looking down.  Zero latitude will make the earth's orbit appear
to be a horizontal, straight line oscillation, as seen from the earth's
orbital plane itself.
     Even the ecliptic system is provincial when we consider the stars.  The
solar system is oriented randomly relative to the plane of our galaxy.  If
you choose to view the orbit of a comet in Galactic coordinates, the galaxy
will appear horizontal and the earth's orbit will appear highly inclined.
Viewing toward Galactic zero latitude and zero longitude is looking toward
the center of our galaxy, in the constellation Sagittarius.
     Speaking of provincial, the bottom line, of course, is that our own
galaxy is oriented randomly in space ....
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                                    PLANETS

HOW TO ...

 ... run the planet options

     Type PLANETS to run the planet options.  Only one version of PLANETS is
compiled on the disk.  It does not use the 8087 math co-processor.


 ... plot orbits of the bright planets

     The planets Mercury, Venus, Mars, Jupiter, and Saturn are bright enough
to be seen easily without optical aid.  Venus, Mars, and Jupiter get brighter
than any star.  The orbit plot routine shows the orbits of these planets as
seen by a hypothetical observer hovering over the Solar System.
>
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     One use of the printouts is to use push-pins to keep track of where the
planets are at any time during the year.  The starting point and the time
interval are indicated at the top.  The easy way to mark out the dates for
the earth is to use the dates running along the side of the planet motion
graph (see later in this "How To..." file).
     One of the things to look for is various alignments.  Be conscious of
the angle between a planet and the sun as seen from the earth (this is called
the elongation of the planet).  The farther the planet is from the sun, the
easier it is to see.  When the outer planets are opposite the sun (at
"opposition") they are also closest to the earth.  This is the best time to
observe them, especially Mars, which gets very close at opposition and quite
far away at other times.
     Consider the sun at noon.  If there is a planet to the left of the sun
(even though you can't see it in the sun's glare), it will follow the sun as
the sun moves toward the western horizon.  Thus the planet will still be in
the sky when the sun sets.  Any planet to the left of the sun is visible
in the evening sky.  Any planet to the right of the sun sets before the sun,
but it also rises before the sun, making it visible in the morning sky.
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|HOW TO ...

... plot a planet finder chart

     Plotting the chart is easy.  Choose whether you want a calendar year or
school year version (all of these printouts lead to interesting classroom
activities for teachers) and the year.  The program does the rest.  You get a
neat chart which you might not understand at first, so keep reading.
>
|HOW TO ...

... use the planet finder chart to understand planetary motion

     First, notice that the dates go down the left side.  This chart is
essentially a calendar.  The line down the center represents the sun.  We are
looking at how the planets move in relation to the sun.  Mercury and Venus
appear to spiral around the sun (ie. they circle it, but the circle is
stretched out along the time axis).  The plot indicates when they pass behind
or in front of the sun.  They happen to change in brightness and phase (like
the moon) as they go around it.  The outer planets also spiral around the
sun, but in the opposite direction.  Actually they appear to move backward
because the earth is moving faster than they are, so we are constantly
passing them by.  (The earth is not shown because this chart represents the
sky as seen from the earth's point of view.)  Try correlating the view of the
planets on this chart with the orbit diagrams.  It's the same data in a
different form.  Keep your mind on the angle between the sun and the planet
as seen from the earth's point of view.
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|HOW TO ...

... use a planet position chart for observations

     The planet motion chart is an excellent guide to when and where to look
for the planets.  Mercury, Venus, Mars, Jupiter, and Saturn are as bright or
brighter than the brightest stars.  All of the planets follow the same
general path through the sky called the ecliptic, which is marked out by the
motion of the sun through the sky.  In order to locate a planet it is usually
sufficient to know about how far and in what direction a planet is from the
sun.  Any planet too near the sun will be hidden by the sun's glare.
(Mercury is always near the sun, so it is almost always hard to find.)  Any
planet to the left of the sun is visible in the evening sky, and any planet
to the right of the sun is visible in the morning sky.  The outer edge of the
chart wraps around.  When a planet disappears off one edge, it reappears on
the opposite edge.  The dashed lines are 90 degrees from the sun, so a planet
on the dashed line to the left of the sun is visible "overhead" at sunset.
(Actually it will be to the south of overhead if you are a northern
hemisphere observer.)  When an outer planet is near the outside edge of the
chart it is near opposition: overhead at midnight and closest to the earth.
The motion of the planets is easiest to detect in the sky when two planets
pass.  You can use the chart to look for occasions when this will happen.
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                                  Conclusion

     This is a start of what I hope will grow into an integrated
computer/handbook guide to astronomy.  You can get in on the ground floor and
participate with the growth of this project by becoming a registered owner,
by helping to distribute it to interested friends and colleagues, and by
writing in about bugs, incompatibilities, and suggestions for improvements.
>