Fresh Fish 1/FFMCD01.bin/bbs/libdisks/d600t699/disk643.lha/DSDemo/Manual

Text File | 1992-04-26 | 40.8 KB | 941 lines

                      DISTANT SUNS 4.1 Demo Version
                     Copyright 1992 by Mike Smithwick

Welcome to the DISTANT SUNS demo! This is a near complete working copy
of the Amiga planetarium program, DISTANT SUNS available from Virtual
Reality Laboratories. This program may be freely redistributed as long
as this file is kept intact.

Originally named "Galileo" when it first appeared on the market in
1987, DISTANT SUNS has earned a reputation as one of the most complete
general purpose computer planetarium programs. Now in its fourth
version, DISTANT SUNS has collect numerous awards. It was named "Most
Innovative Educational Product of 1988" at the Summer 1988 Consumer
Electronics Show. In 1989 the readers of Amazing Computing selected it
as their favorite educational software, and in the same category, the
Amiga developer's community give DISTANT SUNS the "Developer's Choice"
award at the 1991 Commodore Developer's Conference.

DISTANT SUNS requires a machine with 1 meg of memory or more. While it
will run on a stock 68000 Amiga it is easy to load the program down so
much as to make the operation quite slow. Many tools are supplied to
turn off objects and features when not needed to speed up operation.

Two demo versions of DISTANT SUNS are available. The "1.3/FFP" version
runs under 1.3 and uses software floating point calculations. The
"2.0/FPU" version needs AmigaDos 2.0 and a floating point coprocessor,
such as the 68881 or 68882 chip (which will speed things up at least
3 times).

DISTANT SUNS is normally distributed on 3 disks, in order to trim it
down to fit on a single disk a number of compromises had to be made.
The normal distribution star database contains about 4200 stars which
had to be cut down to just over 3700 (all stars
brighter than magnitude 5.7), or about 2/3rds of what
the human eye can normally see (about 6000). The lunar images
have also been limited. In the real software different bitmapped
images are supplied for each day. These took up too much disk-space,
so only 6 lunar phases are supplied.

This demo will limit you to observing in the year 1986 only. 1986 was
selected so you could observe Halley's Comet in case you missed it.

AREXX has been disabled, as well as overscan support, although high-
res and medium resolutions are available. You cannot precess the stars
nor can you add new orbits to the system (comets, asteroids, etc.).
The anim facility has been disabled, however anims made by DISTANT
SUNS may be available on your local BBS. You cannot save a screen to
IFF or save events to a file. The "Twilight" and "Startrail" options
have also been turned off. You will be unable to use any of the
"Extended Star" databases, which would normally give you access to up
to 255,000 additional stars.

I know that this is probably overkill for a demo version, but some of
the options just took up too much space, so getting rid of them was
more out of necessity to free up room on the disk then to limit
usability.

                             Getting Started

The demo distribution disk is not bootable. Meaning that if you are
running only a floppy based system you will have to use your normal
Workbench disk in the normal fashion.

Before starting up the program, click on the "Install Fonts" icon.
This will install 3 fonts that DISTANT SUNS needs into your font
directory. Make sure to have about 5K of memory free if you're running
from a floppy based system. If you have a harddrive, simply drag the
"ds" icon over to the desired directory on the hard-drive. The
program must be started up from the parent directory, otherwise it
will not be able to find the need files.

Once installed, you may click on either of
the icons to start the program. "Ds_4.1" will start up the program in
it's default configuration, and "halley's comet" will start it up
looking back at the solar-system at the nearest approach of the comet.

The default startup configuration will center the north star, Polaris,
in the middle of the screen. The field-of-view (FOV) is at 180
degrees, so you see the entire northern hemisphere of the sky. Your
mouse serves as the main navigation tool. In the default "point and
center" mode, merely click anywhere on the screen with the left mouse
button, and this point will snap to the center.

You will also notice the simple control panel. The two buttons control
the field-of-view. You are limited to values between 180 degrees (like
a wide angle camera lens) and 1 degree. An angle of about 60 degrees
is most natural. (Besides those buttons you can also zoom in via the
FOV menu, under "Display" or by the drag-zoom mouse option found in
the "Preferences" menu, discussed later).

DISTANT SUNS defaults to a non-interlaced screen, 640x200. If you have
more than 1 meg you may want to run in interlaced mode doubling the
resolution and creating a much more pleasing display.
In order to do so you will have to change the tool-types
as described at the end of this document in the section called
"startup configuration".

                           BASIC CONCEPTS

It is at this point that we ought to take a brief moment to
explore some of the basic concepts of observational astronomy,
which will help you in working with DISTANT SUNS.

For starters, it is helpful to think of the sky in the same way
the early astronomers did -- by imagining the stars and planets
as being attached to the inside of a hollow sphere with the earth
at the center. This sphere, in turn, revolves around the earth,
creating the stellar motions.

Variations on this theme had each planet on a separate
crystalline sphere revolving on its own, which explained their
independent movements. But for now, the single sphere model will
do.

Another concept which is essential for understanding how
astronomers describe the various locations of celestial objects
is that of coordinate systems.

We are all familiar, in one way or another, with coordinate
systems. This is a method of specifying the location of a
particular place, be it on a piece of paper or the Earth. Our
home addresses for example, represent one coordinate system, the
earth's latitude and longitude lines are another.

In order to pinpoint the location of a star, astronomers have
developed their own system for the sky analogous to the earth's. The
sky's latitude is termed "declination", (or "dec")

and its longitude "right ascension", (or "RA").

In this "equatorial coordinate system", declination is measured
in degrees, as is latitude, and like latitude, ranges from -90
degrees to +90 degrees. Zero degrees declination is called the
"celestial equator".

Right ascension, on the other hand, is measured not in degrees,
but in hours, minutes and seconds, with each hour being the
equivalent of 15 degrees.

A second coordinate system that is important is the "horizon"
system used in specifying the location of an object in your own
sky. The two coordinates used are "azimuth", or compass heading with
North being 0 degrees, and "altitude", or the angular elevation above
the horizon. Both are measured in degrees. And while right ascension
increases by motion towards the left, azimuth increases to the right.
Because of the earth's rotation, horizon coordinates of a
particular object are constantly changing, while its equatorial
coordinates are constant. DISTANT SUNS defaults to using the
equatorial coordinate system called "Planetarium Mode", as opposed to
your local coordinate system. This was done for two reasons :

    * Planetarium mode is much faster which makes navigating
      around the sky all the easier.

    * Planetarium mode removes the ambiguities introduced by
      using your local system. That is, Rigel's equatorial coordinates
      are going to always be the same, but its local horizon position
      changes constantly.

                              MENU CHOICES

Now that you've had a chance to checkout the control panel, let's look
at the menu choices available to you. The following sections will
summarize the options. (Notice that a number of the menu items have
keyboard equivalents, and that some options are mutually exclusive
with others. Selecting these will automatically lock out others).

-------------------
SYSTEMS MENU
-------------------

The Systems Menu supports basic systems level and initialization
functions.

About DISTANT SUNS

This will display authorship and copyright information. It keeps the
lawyers happy. As this is a demo version it may be freely
redistributed as long as this file is kept intact and with the
software.

AREXX (not available in this version)

Selecting "open" will permit DISTANT SUNS to accept AREXX commands.
AREXX is a high-level language which was designed to control programs
externally. For instance, you may use AREXX to have DISTANT SUNS
control a telescope. Or you may create a new interface using a
combination of AmigaVision and a touch-screen for a museum exhibit. If
you are running AmigaDos 2.0, AREXX is included. Otherwise you may buy
it from your local dealer.

Clock (new to version 4.1)

The "control" option opens up a panel which will permit you to control
how the programs internal clock behaves. When first opened, the system
will read some interpolation tables off of the disk to initialize
internal arrays. There are 5 different clock modes selectable in the
"mode" cycle gadget, the default being "fast". With the fast mode
chosen, clicking on the left or right arrows with the left mouse
button will increment or decrement the date and time, based on the
selected increments and units.

Holding down the mouse button will cause the time to continue to
change as fast as the machine will allow, until the button is
released. (A math coprocessor is highly recommended for this feature,
increasing the speed by about 300%). When in this mode, the moon's
phase will not update until you release the button, nor will the solar
corona load in during an eclipse. This was done for the sake of speed.
Also, any object locks are temporarily disabled. In order to
demonstrate this, center the sun using the "search/sun" selection in
the Display menu. Set the increments to 1 day (should be the default),
mode to "fast", and click on the left arrow. You will notice the sun,
moon and planets all moving ahead in time. The moon will move the
largest amounts, covering about 15 degrees per day.

The "real" mode, sets the system to real time. The screen will update
about once every half minute, keeping track with the system clock.
This is useful if your are out in the field, so the display will match
the sky all of the time.

"Freeze" stops the clock activity altogether. "Manual" will quickly
update the clock once with each click on the arrows. This will give
you very fine control over the system to investigate more closely
timed related events. Manual is no different then changing the time in
the Environment window and hitting USE, and is included here for
convenience. Because of this, the "trail" options in the Prefs menu
have no effect.

"Auto" is just like manual except it will automatically update the
screen continuously, leaving a few seconds between updates so you can
have access to the menus. And like "manual" it too will not leave
trails.

Also in the Clock menu is the "real-time" and "freeze" options. These
are identical to the modes in the control window, acting as
alternatives to those selections if the window is closed. So if "auto"
is on and you wish to turn it off, instead of having to open the
window and cycle through the modes, merely select "freeze".

Environment

At startup, DISTANT SUNS will read the current date and time from
your computer's internal clock. If you haven't set it, you'll
need to put in these values yourself.

Selecting "environment" will open up a large window showing the
current time, location, etc. needed by DISTANT SUNS at startup.

You may change any of the values at will by simply clicking on
them with either of the mouse buttons. The left button will
increase the displayed value, the right will decrease it. A
single click of the buttons will change the value by one step,
whereas holding down on the button will cause the values to cycle
automatically. The longer the button is held, the faster they
will change. In order to make use of the right mouse-button the menus
are not available from this window. In order to access the menus,
merely activate any one of the other window and use the right button
in the normal fashion.

DISTANT SUNS tries to account for the proper time-zone depending
on the supplied longitude. Unfortunately, due to the irregular
nature of the zonal boundaries it is impossible to be sure if the
calculated figure is correct. Moreover, not all countries, states or
regions adjust for daylight vs. standard times. DISTANT SUNS
always assumes standard time. If the longitude is changed to another
time-zone, the value will be recalculated for standard time.

DISTANT SUNS will allow you to enter any date between 4713 BC and
9999 AD. However, the further you go from the current date, the
less accurate the calculations are likely to be. This is due to
the many subtle motions in both the earth and stars. Also with
this wide of time span we may come across precision limitations with
the systems math libraries.

If you made a mistake when changing the parameters, clicking on
"cancel" will return to the values present when the window was
opened. "EXIT" will merely close the window, while "ok" and cause the
program to make use of the new data but will not exit. (These button
conventions are consistent throughout the entire program.)

Clicking on "save" will save the location data, which will be used for
the default startup in the next session.

The "julian date" is the "absolute" date used to pinpoint astronomical
events. This is the number of days from the date (the "fundamental
epoch") January 1, 4713.

"UTC" is the "Coordinated Universal Time", better known as Greenwich
Mean Time, or the time at the Greenwich Meridian. This is used as an
absolute time whenever one needs to coordinate activities which
stretch across time-zones.

The default location is set for San Francisco.

Flushmem

If you are running with limited memory, you may run too low to perform
certain operations if too many objects are loaded. Flushmem will purge
the internal memory of some of these extra objects. Currently this
will take care only of the "Extended Stars".

Mem monitor

This will display a simple memory monitor which you may want to check
periodically when running on a 1 meg machine with alot of data loaded.

Quickview

Quickview will quickly set up the display in Local mode, oriented
toward any one of nine directions, much like a macro. The horizon
line, and constellation and planetary names will also be switched on.
This saves you the time it would otherwise take to turn on everything
separately and wait through several screen refreshes.

The horizon line indicates where your own horizon is, marking
every 10 degrees.

The "up" option will display the entire sky as seen from the selected
location. (Because of the wide field-of-view, the constellations near
the edges will be "scrunched up",looking like the sky is viewed
through a fish-eye lens.) The display is drawn as if you were
outdoors, oriented North, looking up. That way, North would be "below"
your chin, or down relative to your face.

No Exit is required from Quickview--just select your options as
you normally would.

Redraw

With the many options that DISTANT SUNS offers it is possible
that from time to time various screen elements may trash others.
Redraw will simply refresh the entire screen to clean it up if
possible.

Reset display

Sometimes you may want to turn off all of the objects and
identifiers previously loaded onto the screen. Reset will turn
off all selected items all at once, returning the sky to a plain
unadorned state.

Reset clock to present (new to version 4.1)

This is a painless way to reset the time and date to current values.

State

A "state" is the current configuration of the program, time, location,
options selected, lookangle, and so on. This option will permit you to
save and restore various states to your liking. One sample state is
available demonstrating Halley's Comet.

In this demo version you may not save a state.

Quit

Exits the program (so what else is new?).

--------------------
DISPLAY MENU
--------------------

The Display Menu will controls the major display elements and
operation modes.

Mode

There are two main display modes DISTANT SUNS uses : "Local" and
"Planetarium".

In Local mode, the sky will be displayed as seen from the
supplied time and location. Using Quickview under the System menu
is the suggested way of entering Local mode to save time spent in
setting up the screen to the most common configuration. Under this
mode, the sky changes from night to night and from one point on Earth
to another. Furthermore, the local coordinates of the stars, their
"altitude" and "azimuth", will change as the Earth rotates. If you are
in the Northern hemisphere you will notice the North Star, Polaris is
at an altitude above the Northern horizon equal to your latitude. Were
you exactly at the pole, the sky would resemble Planetarium mode. The
default location is set for San Francisco.

In Planetarium (the default) mode, the sky is displayed as if
there were no earth underneath to distort your perspective. This
removes any ambiguities that your own location introduces.

You will no doubt notice how much slower Local is when compared
to Planetarium mode. This is because DISTANT SUNS must do an
additional rotation for each star in order to shift the perspective to
your own frame of reference.

Constellations

The names of the constellations may be activated by selecting the
"names" option. The same applies for the outlines. Each may be
turned off by selecting the item a second time. Take note that
generally the names are located away from the center of the
constellation so as not to clobber important stars.

The 12 constellations of the Zodiac are identified by the yellow
names.

Deep-Sky

"Deep-sky objects" are those non-stellar entities outside of our
own solar-system, such as galaxies, star clusters, and so forth.

The "Messier" and "NGC" selections will display entries from two
of the most popular deep-sky catalogs. The Messier catalog
contains 110 entries, and the NGC or "New General Catalog" has
over 10,000 listings of which the best 1967 are shown here.

"Legend" opens up a window to aid you in quickly identifying the
various types of objects.

Extended Stars (not available in this demo)

This will load in stars on demand from a more detailed file. The files
will form a set of expansion disks, going down to about 10th
magnitude, covering the entire Skymap database of over 250,000 stars.
Since this database is about 20 meg in size, the user may purchase
areas of interest, ("Vanna, I'd like to buy Orion"). To load these
stars, merely zoom in to the area of interest, select the menu item,
and the stars in and around the visible region will be loaded.

These stars can take up a significant amount of memory, so using
flushmem is recommended if you don't anticipate needing them anymore.

Also, the dimmer stars are likely to be so dim you may want to either
turn  up the brightness of your monitor, or use a brighter colormap
option, explained later.

Field-of-View

This selection will aid you in quickly moving to a particular
field-of-view from 3 to 180 degrees. Besides this you can also use the
buttons on the control-panel, or the drag-and-zoom option with the
mouse.

Landscape  (not available in this demo)

Landscape will turn on an artificial horizon to simulate
mountains in the distance. With this activated, your vertical
scrolling is limited to a range of +/- 20 degrees in altitude. You may
adjust the landscape profile to match your own location, see the
chapter on User Data for further information.

Lookdown

Lookdown will display a view of the solar-system from above.
"Inner Planets" will show the orbits from Mercury to Mars.
"Middle Planets" covers earth to Jupiter, while "Outer Planets"
will show you Jupiter to Pluto.

These selections act merely as macros to the off-earth mode (discussed
below). That is, selecting the view of the inner planets is no
different than if you were to move your eyepoint to 10 astronomical
units directly above the sun, and then turn on the planetary orbits
option.

Markers

The Markers menu will display additional information to aid
you in further understanding how the stars are laid out in the
heavens. "Altitude" will turn on an altitude line when in Local mode.
This will show you the altitude above the horizon in degrees. The
"ecliptic" denotes the plane of the solar-system based on the earth's
own orbit. "Celestial equator" will display the projection of the
earth's equator up against the sky. This is the imaginary line which
separates the northern and southern hemispheres of the sky.

The "horizon-line", shows your own horizon projected against
the sky. In Local mode, it will be horizontal to the bottom of
the screen. (It will be 5 degrees above the true horizon if the
landscape is on.) In Planetarium mode you will see the line at an
angle because your own point of reference is itself tilted due to
your latitude.

The "Grid" selection will overlay a right-ascension/declination
grid on top of the stars, much like the grid in a star atlas.

Move

This permits you to move to a specific point in the sky, specified by
either equatorial or horizon coordinates. The slider may be used to
set the value, or you  may type it directly into the text-box for more
precise movement. The active "radio button" specifies which box the
slider is bound to. When the slider is moved the text value is
updated, along with the values in the alternate set of coordinates.
That is, if you want to change the declination, click on its button
that grab the slider. You will notice the declination value updating,
along with the values for the altitude and azimuth. The right
ascension will remain frozen.

Search

Selecting "antipode" will move your eyepoint to look directly "behind"
your current lookangle. So for instance, if you wanted to find the
earth's shadow, you could center on the sun and select this. (New to
4.1).

The "by name" option will let you specify an object by its name to
search for. (However the object must be loaded in order for it to be
found. That is, if you are hunting for an NGC object, and the deep-sky
objects have not been loaded, it will not be found.) When running the
AmigaDos 2.0 version, you may use the standard Amiga wild-card
convention. If you are running under 1.3, use a "*" instead. For
instance, if you were search for the constellation of Andromeda, you
could type "and*", and the "*" would effectively fill out the rest of
the name. Hitting "return" will cause the search to take place.

The "constellation" and "solar-system" selections will bring up a
scrolling list of the possible selections. Simply click on the desired
name, hit "ok" and the item will be centered.

"Other" is a user definable search list. As with above, a scrolling
list will open, but you may create the list of objects you have a
special interest in. Unlike the above search operations, this list
does not rely of loaded objects. Instead you specify the desired name,
location and field-of-view. This way you can center on interesting
parts of constellations or back out far to look at a large region.

The next two menu items provide quick access to the Sun and the Moon,
since these are likely to be the most commonly searched for objects.

"Zenith" will point you to the location directly overhead. (New to
4.1).

Viewpoint

This is perhaps one of the most interesting features in that it
permits you to move your eyepoint out from Earth and look back on the
solar-system as a celestial traveller might see it.

The "Earth" option is used to place your location back on earth.

"Fixed" will put your eye at some fixed point in space, out to some
400 astronomical units (one astronomical unit, or "AU" is equal to 93
million miles, the distance from the earth to the Sun) away from the
Sun or 10 times further than Pluto. The location of an object in the
solar-system is typically given in "Heliocentric (Sun centered)
Coordinates", measured in latitude and longitude. The heliocentric
latitude is measured from the plane of the earth's orbit and the
longitude from the "First Point of Aries". Both are expressed in
decimal degrees and the distance in AU. The default setting is 35
degrees above the plane of the ecliptic, 0 degs from the First Point
of Aries, and 10 AU from the Sun. Hit "OK" and stand back. Way cool,
eh? Changing the latitude to 90 degrees will put you directly over the
solar-system, identical to the lookdown viewpoint described above.

The "other" selection will attach your eyepoint to an object orbiting
the Sun. If the orbital traces are currently switched on you will see
a number of gray lines crossing across the center of the screen. You
can turn them off in the prefs window if you like. The objects own
orbital trace is turned off, otherwise it looks strange when compared
to the others.

"Prefs" will allow you to fine-tune the scene :

                orbits - toggles on/off the orbital outlines.

                orbit dlines - this will render droplines from the
                         object to the ecliptic. If the line ends in
                         a green dot, the object is above the plane
                         if red, it comes from below the
                         ecliptic. The droplines are best seen on
                         Plutos orbit or that of a comet. Since
                         each orbit requires many droplines, this
                         option will slow things up significantly.

                 object dlines - this will render a dropline from
                         each object to the ecliptic. As above
                         green indicates the object is above the
                         ecliptic, a red line, below.

                 grid - this will draw a grid on the plane of the
                        ecliptic, 10 units on a side.

                 grid-size - changes the size of the grid (in AU) from
                        .5 up to 20.

-------------------
EXTRAS MENU
--------------------

Earth's Shadow

Renders the earth's shadow as a large round circle at  the moon's
distance. Useful mainly to demonstrate lunar eclipses.

Lock

"Select" will choose an object to lock on. This means that the object
will always be centered no matter what. Hence none of the centering or
move modes will work. This is most useful when producing animations,
or when looking at an object over a long period of time saving you the
trouble from having to re-center it. Object locks are not recognized
when using the "fast" clock mode.

In order to break the lock, select "release".

Precession (not available in this demo)

Normally no precession is performed on the stars, since it takes
a long time whether it is needed or not. Selecting
"auto-precess" will cause the stellar data to be updated if the
date is changed by more than 200 years. The "stars" option will
precess the stars on demand, should you require greater accuracy.
Any extra objects such as deep-sky or user data, will also be
precessed. So the more you're displaying the longer things will
take.

Normal precession ignores the outline data. In part a time saving
measure, but this also permits you to compare the previous
stellar positions with the new ones, by using old outlines.

Sky-images

A practically useless option. "Dynamic" (the default) will rescale the
Sun and Moon images so they always present an authentic size for the
given field-of-view (between 3 degrees and 30 degrees). If for any
reason you feel the the images are too small for the wider fields,
selecting "fixed" will scale the images for 15 degrees no matter how
big or small the field is. This might be useful for auditorium
demonstrations when the audience is far away from the display.

Skylight (not available in this version)

Selecting Skylight will make DISTANT SUNS attempt to duplicate
the ambient light generated by cities or towns that wash out
dimmer stars. In other words, if you live in downtown Cleveland,
the sky will look a great deal different then it would from
Buffalo, Wyoming. In fact, many people find it hard to identify
constellations in a country sky because there are just too many
stars.

Star Data

This option will place the selected data field alongside each star on
the screen.

One word of warning: Use a fairly small field, otherwise the data
density could become so great, nothing will be readable. Also, the
more stars on the screen the longer the process will take. A field
wider than 30 degrees should be avoided when using the standard
database, or 15 degrees when using any of the extended databases.

Star Trails (not available in this demo)

A persons first encounter with astro-photography is usually
through the taking of stellar time-exposures with a camera fixed
on a tripod. The results will produce streaks, or "star trails"
caused by the motion of stars across the field-of-view. This
phenomenon may be simulated by going into Local mode, setting
the clock to automatic and increments to 5 minutes, and then enabling
this option.

Twilight (not available in this demo)

The twilight mode is meant to simulate daytime. Turning on
twilight will do different things depending on what viewing mode
you are in. If you're in Local mode the sky will be a bright blue
while the Sun is "up". As the Sun sets below the horizon, the sky will
darken and the stars will begin to emerge.

In Planetarium, since the Sun is always "up", the sky will be
blue all of the time, unless of course, there is a solar-eclipse.

Twinkle

Selecting this operation will cause the stars to twinkle while you are
on the Earth. If you're out in the solar-system there is no atmosphere
to interfere with the starlight so they cannot twinkle.

User Data (not available in this demo)

The user may supply a custom list of up to 20,000 objects, which is
loaded and displayed by this option.

------------------
PREFS MENU
--------------------

Control Panel

This will open the control-panel if it had been closed.

Colormap-IF

Depending on your specific needs you may want to change the colors of
the interface. "Dim" and "red" are used to preserve the "night-vision"
of an amateur astronomer who might have his/her Amiga propped up next
to the telescope. Night-vision is when your eyes have fully
adjusted to the darkness, maximizing their sensitivity. As it
takes over 30 minutes to reach this state, astronomers are
reluctant to use any lights during an observing session. When
necessary, red lights are traditionally used. The "red" selection
will turn everything in the display (except the stars) various
shades of red. For the more aesthetically oriented observer, the
"dim" option was added which preserves the colors, but merely
darkens them. This has a side effect of changing the colors on the
planets as well since they reference the same colors used by the
interface. "Normal" will cancel the other options.

Colormap-Stars

"Bright" will increase the apparent brightness of the stars. You may
want to use this if you are in a brightly illuminated room to make the
stars easier to read, or if you are using an expansion database with
many very dim stars.

"Color" will display the stars in a variety of different colors to
more clearly show the magnitude distribution.

Crosshair

Turning on the crosshair will pin-point the center of the screen.

Info

This will stamp basic information such as date, lookangle, etc, in the
upper-left corner of the screen. You would normally use this when
creating animations.

Mouse-control

This determines how the left mouse-button is to be used. The default
is "point-and-center". By putting the pointer over a location of
interest on the screen and hitting the left mouse-button, DISTANT SUNS
will center that spot.

The second mode is "identify". The mouse pointer will now change into
a crosshair. By centering an object in the crosshair and clicking the
left button, a data window will appear. Several windows may be
displayed depending on what the object is. For a star you will see the
normal data detailing the star's brightness, location, spectral type
and so on. Some stars will have associated comment files which will
give further notes, historical and otherwise. For deep-sky objects, in
addition to the data and comment windows, you may see an actual image
if you have the image-expansion disk. Two sample images are supplied,
one for "M101" and the other for "M57". You will experience a slight
delay when this mode is activated. DISTANT SUNS is redrawing the
screen, but this time it is storing away the visible objects making
this mode possible. This process will slow up a screen refresh, so use
it only when needed. In order to see the images, turn on the "Messier"
object list, DSO names, and search for M57. When centered click on it,
and a data window will open along with a brief description and image.
In the data window you will notice a button labeled "view". If
unghosted, there are full-screen images available which may then be
displayed by clicking on the button. For this demo, only a single
image is included for this object only. In the full version of the
software over 20 images are supplied on the third disk. The user may
also add their own to any object and as many as desired so as to
creating virtual slide shows for the moon, planets and deep-sky
objects. Great for when the in-laws come over or for a school science
project.

The third selection for the mouse is "zoom". This will turn your mouse
pointer into an angle-bracket and will permit you to zoom into a
region of interest merely by drawing a box around it. Hold the left
button down, drag the mouse to surround the area with the "rubber"
box, and release it. You may not zoom any close than a 1 degree field
of view.

Show mag

At times you may want to limit the displayed magnitude of the stars.
The "show mag" window will let you do this. Merely select the dimmest
magnitude you desire to display, and hit the "OK" button. "All" will
reset the slider so as to display all of the stars.

You may want to use this to limit the number of displayed stars if you
are running on a slower machine. Cutting the magnitude down to 5 or
even 4 will dramatically speed up operations. Then you can bring up
the dimmer stars once you have the configuration you desire.

Show objects

"Planets" will display a window letting you selectively turn on or off
any planets for display, along with the moon. This would be used
mainly for two reasons. As with "Show mag" above, turning off unneeded
planets will make operations faster if you were performing a "track"
on a planet. Also, if you were looking back at the solar-system from
some distant point, having all of the planets on may cause unnecessary
screen clutter. Particularly if you are trying to produce an
animation.

"Other" will filter out miscellaneous objects. If you are interested
only on solar-system operations you may want to turn off the stars
completely with the "stars" item. If the names of the deep-sky objects
interfere with each other you may want to turn them off by using the
"dso_names" button. Finally, you may selectively turn off several
classes of deep-sky objects, once again to remove screen clutter.

Titlebar

This will turn on/off the titlebar. If you are running under AmigaDOS
1.3, you need the titlebar to drag the screen down.

Tracker

"Animate symbols" will cause the planetary "symbols" (their dot and
name if turned on) to be animated when using the fast clock animation
mode. Those with slower machines may want to leave this off, in order
to speed up operations. "Object droplines" is the same as the "object
dlines" check-item in the OEV-Prefs panel. This will do nothing when
you're eyepoint is on the earth. When off the earth, in in "fast"
mode, the droplines will be rendered at each update, and left on the
screen giving a unique perspective on the orbits. "Trails/lines" will
cause the objects to leave lines in their wake, and "Trails/points"
with do the same, but with dots at each update.

--------------------
TOOLS MENU
--------------------

Anim control (not available in this demo)

This will open up a window on a separate screen to help you create an
animation file.

Chart

The "Chart" function will display the entire sky as a Mercator
projection. This will give you a sense of how the stars and deep-sky
objects are distributed. The white-box outlines the general area
displayed in the main screen. A small control panel will let you turn
on/off the grid lines, stars, constellation names and the dso objects.

Clicking anywhere in the window acts just the same as point-and-center
does in the main screen, so chart may be used as yet another aiming
device.

Custom SS object

"New orbit" will let you create or add a new object to the solar-
system such as a comet or asteroid. (Not available in this demo).

"Load" will load in a custom solar-system object. The more objects you
have loaded, the slower the system will be, so use "unload" to remove
any unneeded objects.

Ephemeris

An "ephemeris" will give you a location table for a desired object
over a period of time. In the ephemeris window, select the object via
the "object" button. Enter the range of dates and increments in days
for how frequently the data is to be calculated. For the inner planets
you would probably want to make this "1", for the outer-planets use
longer intervals unless you need great accuracy.

"Print" will dump the data to the printer, and "save" will save it to
disk.

Flashcard

The "flashcard" tool will aid you in learning to identify the
constellations. Turning on flashcard will switch off all of the
identifiers on the screen, center the screen at a random location and
challenge you to figure out just what you're looking at.

The identifiers may be toggled with the "on" and "off" buttons in the
flashcard window. "Flash" will turn off everything again and jump to a
new location. Exiting flashcard will restore you to your original
state.

Mag window

This will display a simple magnitude legend.

Save to iff (not available in this demo)

From time to time you may want to make a screen dump to take outside,
or on a trip to use as a reference. "Save to IFF" will let you do
this. The screen shot may then be loaded in your favorite paint
program and then printed out. While in the program you may want to add
any explanatory notes or diagrams.

Tables

"Tables" will let you create your own on-line reference system by
displaying any simple text file in a listbox. With this you may want
to add tables of upcoming eclipses, favorite variable stars, and so
on. Two tables are supplied, one for the major meteor showers of the
year, and the other for the Greek alphabet.

What's Up?

The What's Up? screen provides you with a simple quick overview of
what's going on in the sky that night.


                        Startup Configuration


DISTANT SUNS will let you define your own startup parameter through
the use of "ToolTypes" situated in the icon. On the boot-disk you will
notice two DISTANT SUNS icons, one labeled "ds_4.1" and the other
named "Halley's Comet". Click on this, and
open up its "Information" window. (Under AmigaDOS
1.3, this is the "info" menuitem in the Workbench menu, and under 2.0,
it is "information", located in the Icon menu.) In the window called
"Tool Types" you will see a couple of lines which define the program's
startup configuration.

The RES argument specifies what resolution you want the program to run
at. On a machine with only 512K of CHIP RAM (A500s or A1000s), you can
only run in medium-resolution (non-interlaced) modes due the limited
memory available. RES will be followed by one of three mode values,
"med" for medium, "hi" for high-res interlaced and "over" for
overscan. These resolutions cannot be changed once the program is
running. If you are running on a PAL machine, the resolutions will be
adjusted as required. That is, the "hi" mode under NTSC will be
640x400, while under PAL it will be 640x512. The use of a deinterlacer
is recommended when running in interlace mode unless the flicker
doesn't bother you.

The other Tooltype, STATE, will cause the desired state file to be
loaded. A state file contains all the information needed to set up the
program to a certain date, time, location and option configuration.
Therefore the state-file for Halley's Comet will jump you right to a
view of the comet requiring no work on your part. Once in the program,
it will operate normally.

ORDERING INFORMATION :

DISTANT SUNS 4.1 should be available at your local Amiga dealer by the
time you read this for a "suggested price" of $99.95.

DISTANT SUNS is also available for IBM and clones running Windows
version 3. (Of course it is missing the options which are unique to
the Amiga).

Current owners may upgrade by sending in their original disk with
$10.00 to Virtual Reality Labs, 2341 Ganador Ct., San Luis Obispo, CA,
93401. [phone].