Copyright: Copyright © Relative Data Products


Contents

MyStars! Version 2.2

This software is shareware, it is not free software. Please read the registration information ($12) for more details.

Program Description

System Requirements

Disclaimer

Installation

Image Credits

Whats New:	Update Log

Program Startup

Menu Commands

Mouse Effects

Program Shutdown


Program Description
Program Description:

WHAT THIS PROGRAM DOES:

MyStars! is a windows program that shows the position of stars, the sun, the planets and the Messier objects as they would be seen from any position on earth. It also allows you to vary the time of view (What did the stars look like the day that I was born?). Various options allow you to view the planet names, constellation names, and several celestial coordinate grids as well. Actual images are shown to scale for the planets. An animation option generates a series of views separated by fixed intervals of time.


View From Location
View From Location:

This dialog box allows you to select the position on earth from where you want to view the sky.

This dialog box is accessible at program startup, from the View menu or by clicking on the Lat/Lng data area.

You can select one of the cities from the list provided, select any latitude or longitude, or you can click on the map of the earth.

Latitude may be entered in degrees and minutes (i.e.: 45 30 N), or as decimal degrees (i.e.: 45.5 N, or 45,5 N). Convenience buttons are provided to set the view from the north pole (Lat 90 N), the equator (Lat 0), or the south pole (Lat 90 S), and convenience scrollers are provided to increase and decrease the latitude by five degree increments.

Longitude may be entered in degrees and minutes (i.e.: 45 30 W), or as decimal degrees (i.e.: 45.5 W, or 45,5 W). A convenience button is provided to set the view from the Greenwich meridian (Lng 0), and convenience scrollers are provided to increase and decrease the longitude by five degrees increments.

With a new viewing location selected, the local time is adjusted if necessary, and the sky updated to reflect the new location.


Registration Information
Registration Information:

$12 gets you the moon!

This is a shareware product. Feel free to experiment with it and find whether it is of interest to you. Freely distribute as many copies of this product to friends and associates as you wish. The only restriction on copying is that you include all the files, without modification, that were originally included in your copy of this software (including this file).

BUT THIS IS NOT FREE SOFTWARE, even if you received it on a CD-ROM, downloaded it from a bulletin board, or got it on diskette. Until you become a registered user, you are entitled only to evaluate it for a period of 15 days, then it must be registered or use discontinued.

If you decide to use the product after 15 days, or use it for educational purposes, I ask you to please register your copies with the author. The registration fee of $12 (including all taxes) per copy 'in your use' supports the development of this product and subsequent versions. Through the registration process the author can determine your needs and include them in subsequent releases of MyStars! 'In your use' refers to each copy of this software in your use. Generally this means 1 copy, but for educational or lan environments it refers to the maximum number of copies generally in use by your institution.

When you register this product, you will receive, through the mail, a registration number. When entered into the program, this will immediately enable the setting of dates from 1000BC to 3000AD on your copy and will allow the moon, with its phases, to be enabled. As well, registration will guarantee you an automatic upgrade to the next version of MyStars! to be sent to you by mail when it becomes available, and subsequent releases for a period of two years. If you have requests, send them at any time.

To register, send a cheque or internaltional postal money order for $12 (U.S. or Canadian) with your name, postal address, current version number of MyStars!, and your E-Mail address (if any) to:

David Patte

Relative Data Products

365 Sherwood Drive,

OTTAWA, Ontario, Canada

K1Y 3X3

Note: Cheques must be drawn on an American or Canadian bank. Sorry, no credit cards. US/International customers, please use correct international postage when writing by mail.

You can E-MAIL me by internet:	dpatte@synapse.net

or by fax:	(613) 728-4240


Disclaimer
Disclaimer:

THIS SOFTWARE IS SUPPLIED WITHOUT WARRANTY, EXPRESSED OR IMPLIED, AND THE AUTHOR IS NOT LIABLE FOR ANY DIRECT OR INDIRECT LOSS ARISING OUT OF THE USE OF THIS SOFTWARE.

This software has been extensively tested for bugs. If any bugs are found the author would be more than pleased to hear of them so that they may be removed from subsequent releases.


System Requirements
System Requirements:

Minimum requirements: 386SX with 2 Megs of memory. Coprocessor not required. Windows 3.1, 95 or NT.


Installation
Installation:

To install, run the INSTALL.EXE program included here from the program manager in windows 3.1 or NT.

From Window 95, run INSTALL.EXE included here from START/RUN

If you are upgrading from an older version of MyStars!, we suggest that the new files be placed in a new sub-directory (folder). Note that you cannot run two different versions of this program at the same time.


Program Startup
Program Startup:

Double-click on the icon for MyStars!

When MyStars! is started, if the product is not yet registered, an About MyStars! dialog box appears showing version, copyright and registration information. After the product is registered, this dialog box will not appear at startup.

Then the View From dialog box appears. Enter the location from which you wish to view the stars, then press OK. Pressing cancel will use the last default location or 45N, 75W (Upstate N.Y.).

Then the View At dialog box appears. Adjust the date and time to specify the date required, then press OK. Pressing cancel will use the program start-up time and date.

A rotating earth indicates that calculations are being performed. When the rotation stops, the sky is displayed. You can then use the pull down menus.


Menu Commands
Menu Commands:

The following menus are available:

File

Used for application control.

Objects

To select which objects are to be computed and shown.

View

To select viewing parameters.

Options

To enable various labels and lines in the display.

Animate

Pops up a dialog to specify an animation rate.

Help

Help on MyStars!


File
File:

The only command here is File Exit, which, when selected causes the program to shut down.


Objects
Objects:

This menu allows you to select which astronomical objects will be computed and displayed. As objects are selected a check mark is placed beside the object type in the menu. Reducing the number of selected objects will reduce the time required to complete computations.

Stars:

Compute and display the stars. They are shown in white.

Planets + Sun:

Compute and display the planets and sun. They are shown as scaled images.

Moon:

Disabled in this shareware product. To get a copy with the moon enabled and showing phases, please read the registration information.

Deep Sky Objects:

Compute and display the positions of the Messier (M) objects. Their positions are shown as scaled circles in magenta.


View
View:

This menu allows you to select viewing parameters.

From Location

Pops up a dialog to select the position on earth from where you want to view the sky.

At Date/Time

Pops up a dialog to select the date and time when the view of the sky is wanted.

Towards

Pops up a dialog to specify the direction, coordinate or object to view towards.

Upto Brightness

Pops up a dialog to specify the magnitude or brightness of objects to be shown.

Ahead Only

Limits the field of view ahead (in front of) the viewer.

Above Horizon Only

Limits the field of view above the horizon.

Zoom

Adjusts the magnification factor.


Options
Options:

This menu allows you to enable and disable various information, symbols and lines on the display. Adding options to the display may slow down some calculations.

Status Bar	Enable/Disable the status bar.

Star Labels	Enable/Disable labels for stars.

Constellation Labels	Enable/Disable labels for constellations.

Solar System Labels	Enable/Disable labels for Sun, Moon and planets.

Deep Sky Labels	Enable/Disable labels for deep sky objects.

Altitude Lines	Add/Remove altitude lines, zenith and nadir.

Azimuth Lines	Add/Remove azimuth lines.

Compass	Add/Remove compass direction markers.

Declination Lines	Add/Remove declination lines and celestial poles.

Right Ascension Lines	Add/Remove right ascension lines.

Ecliptic Line	Add/Remove ecliptic line and ecliptic poles.

Ecliptic Longitude Lines	Add/Remove ecliptic longitude lines.

CrossHair	Add/Remove crosshair at centre.

FontSize	Adjust font size.


Animate
Animate:

This dialog box allows you to set an automatic recalculation interval.

This dialog box is accessible from the menu bar or by clicking on the rotating earth area.

During Animation mode, the specified time interval is added to the view-at time, calculations are redone, and the display is refreshed. This allows the display to show the changes that occur on a day by day, or hour by hour basis. This repeats until Animation mode is stopped. NOTE: During animation mode, all other options and menu commands ARE STILL permitted. It is even possible to reset the View-At-Time if necessary.

Stop Animation:

Select this from the dialog when you wish to stop animation mode.

In Real Time:

Auto recalculate in real time so that the display remains a constant reflection of the current sky.

By Minute:

Auto recalculate for each minute.

By Hour:

Auto recalculate for each hour. It is useful for observing the rotation of the earth.

By Sidereal Day:

Auto calculate for each sidereal day. A sidereal day is the time it takes for the earth to do one rotation relative to the position of the stars. This is slightly less than one civil day. If this option is selected, the stars will not seem to move. It is most useful in viewing the relative motion of the sun compared to the background of stars.

By Civil Day:

Auto calculate for each civil (calendar) day. A civil day is 24 hours, and is the mean time it takes for the earth to do one rotation relative to the sun. This option is most useful for viewing the daily movement of stars and planets.

By Civil Month:

Auto calculate for each civil month. This simply adds 1 to the month number for each refresh.

By Civil Year:

Auto calculate for each civil year. This simply adds 1 to the year number for each refresh, and is useful for seeing the motion of the slow moving outer planets.


Help
Help:

Contents:

Displays the main MyStars! help page.

Menu Commands:

Displays the available Menu commands for MyStars!

Using Help

Displays help on how to use help.

About MyStars!:

This display version information about MyStars!, and asks you to register if you have not already done so.


Mouse Effects
Mouse Effects:

The mouse can be used as a short-cut for entering information as opposed to using the pull down menus.

PROJECTION AREA

Clicking the left button on the projection area will allow you to re-center the display towards the selected direction/coordinate. A dialog will appear allowing you to confirm the request.

If a fixed direction was last specified, the new direction at the selected mouse position will be remembered and the software maintains this new fixed viewing direction.

If a celestial coordinate or an object were last specified, the new celestial coordinate at the selected mouse position is remembered, and the software locks onto this new celestial coordinate for further viewing, constantly adjusting the direction as required.

DATA DISPLAY AREA

Clicking the left button on the data display area will pop up an appropriate dialog allowing you to modify viewing parameters:

Lat/Lng:	pops up the View From Location Dialog

Date/Time:	pops up the View At Date/Time Dialog

Alt/Azi:	pops up the View Towards Fixed Direction Dialog

Rta/Dec:	pops up the View Towards Equatorial Coordinate Dialog

ELat/Lng:	pops up the View Towards Ecliptic Coordinate Dialog

Mag/Brt:	pops up the View Upto Magnitude/Brightness Dialog

Image:	pops up the View Towards Object Dialog

Logo:	pops up the About Dialog

Rot. Earth:	pops up the Animate Dialog.


Program Shutdown
Program Shutdown:

When the application is shut down, the Objects selected, and the View selected (except for the date/time, and the zoom factor) are remembered for the next time it is run.


Update Log
Update Log:

Version 2.2	September 95

- switched setup for 3.x/95/NT install and uninstall

- modified cities file

Version 2.1	July 95

- actual scaled and layered images of the planets are integrated within the display

- dso positions are now shown to scale

- improved star drawing and brightness adjustment method

- added view towards (brightest star in) constellation

- added constellation "common name" labels

- added help

- parallax calculated for moon planets and sun

- added ecliptic coordinates to data display area

- more-improved cities list

- synchronized earth rotation and removed hourglass while drawing

- improved yielding to other applications

- improved menu greying

- added confirmation dialogs when clicking on projection

- clicking on data, or world brings up appropriate dialog

- accept ',' or '.' in dialogs, i.e.: 5,5 or 5.5 = 5 deg 30 min

- added file exit

- moved about to help menu

- objs don't disappear prematurely at edges

- improved meridian labels at poles

- improved parallel drawing

- zoomin now adds 1 mag

- constellations names now gold

- removed dsomag: now only one magnitude selector

- references to "deep space" changed to "deep sky"

- fixed bug: LST before 545 A.D.

- fixed bug: lockup when mag set to minimum value

- fixed bug: positions of uranus/neptune

- package includes README.WRI instead of README.TXT

- dialogs are now based on BWCC.DLL

Version 2.0a	Jan 95

- updated city list (Jan 95)

- improved precession algorithm (Jun 94)

Version 2.0	June 94

- reduced registration fee!! (now you have no reasonable excuse not to register!)

- improved line drawing technique

- added coordinate labels to lines

- added more stars (database now has over 9000 instead of just 1600)

- added star names, bayer & flamsteed ids and YBS #s

- modified star2.dat star file

- added deep sky objects (all Messier objects)

- added dso names, messier #s & NGC #

- added dso mag to display

- added dso2.dat dso file

- enlarged window start size

- added variable font size in projection

- improved bitmap draw method

- added low memory warning dialog

- improved magnitude adjustment technique

- improved label placements (names of some types no longer OVERLAP each other)

- added greying of menus for disabled items

- fixed mag/bright bug

- optimized ahead only option to do less computations

- improved view towards menu

- added view towards object (object tracking)

- added view towards ecliptic coordinate

- fixed to rotate earth the other way, oops

- modified, faster scrolling in dialog boxes

- added fixed point math library

- added interpolated sintbl resource

- added moon phases

- improved stat change checking

- modified crosshair now points N

- added optional status bar

- added below horizon warning

- added Local Sidereal Time (LST) to display

- modified colours

Version 1.1a, September 93

- Enhanced drawing speed

Version 1.1, September 93

- file formats changed (again)

- shutdown data increased to maintain new options.

- map added to view from menu.

- screen layout modified to add new data.

- scale factor added to caption line.

Version 1.0c, February 93

- At shutdown, the list of objects selected and the view parameters selected (except the time) are automatically saved for the next run.

- View from selection is improved to detect the location name.

- Calculation speeds are increased for machines without coprocessors.

- The data file formats are changed.

- The screen layout is modified to have region titles and is better centred.

Version 1.0b, September 92

- Bug fixes.

Version 1.0a, July 92

- Optimized sidereal animation in order to reduce calculations.

- Modified coprocessor and 486 checking to use winflgs

Version 1.0, 1st Q, 92

- converted to C++ for Windows

Rewritten in C for QNX, 1988

Originally written in C for CP/M on the Apple II+, 1985


View At Date/Time
View At Date/Time:

This dialog box allows you to select the date and time of your selected view.

This dialog box is accessible at program startup, from the View menu or by clicking on the Lat/Lng data area.

The date is specified as year/month/day and convenience buttons are provided to move the date ahead or back one day.

The time is specified as hour:minute:second in 24 hour format (midnight is 0:00:00) and convenience buttons are provided to move the time ahead or back 20 minutes.

You can also choose whether the displayed time is Local time, or Greenwich Mean time. When Local time is selected, you can specify whether Daylight Savings Time or Standard Time is selected.

To reset the time to that of the current system clock press Reset/Now.


View Towards
View Towards:

This menu allows you to specify the direction, celestial coordinate or object to view towards. The selected direction or coordinate is then maintained in the centre of the display, and a checkbox remains in this pulldown menu to indicate the item chosen:

Fixed Direction

Pops up a dialog to set a fixed viewing direction by horizontal coordinates.

Equatorial Coordinate

Pops up a dialog to lock onto a celestial coordinate specified by equatorial coordinates.

Ecliptic Coordinate

Pops up a dialog to lock onto a celestial coordinate specified by ecliptic coordinates.

Object

Pops up a dialog to lock onto a specified celestial object.


View Ahead Only
View Ahead Only:

This limits the view to only those objects in the field of view ahead (in front of) the viewer, the hemisphere directly in front of the viewed position. When disabled, the view is allowed to wrap around and fill the display area, showing more than a hemisphere.


View Above Horizon Only
View Above Horizon Only:

This limits the view to only those objects above the viewers horizon. Normally this option is on, and the earth, in green, prevents viewing objects below the horizon. When disabled, the earth disappears and objects below the horizon become visible.


View Zoom
View Zoom:

Zoom In / Zoom Out:

These allow you to zoom the objects at the center of the display. Note that zooming in will also automatically increase the limiting magnitude of displayed objects by 1.0. The caption line will indicate the current zoom factor, and the data display area will show the effective increase in magnitude.

Zoom Restore:

This restores the display to normal view (unzoomed).


View Upto Magnitude/Brightness
View Upto Magnitude/Brightness:

This dialog box allows you to specify the limiting magnitude and relative brightness of stars, and deep sky objects to be shown.

This dialog is accessible from the View menu or the Mag/Brt data area.

Reducing the limiting magnitude will reduce THE NUMBER of stars, or deep space objects to be computed and shown. Stars beyond the specified magnitude will not be calculated. This will also reduce the amount of time required to perform calculations. The default value of 4.00 is recommended. Note that zooming will temporarily augment this value.

The percentage brightness acts as a GENERAL BRIGHTNESS control for the current stars being displayed. Use the brightness control if the displayed stars are not bright enough for your monitor. The default value of 0.00% is recommended. Brightness has no effect on computation time.


Options Star Labels
Options Star Labels:

Options Star Names / Bayer&Flamsteed Ids / YBS Numbers:

This enables labels to be displayed in gray for the stars. These will be displayed above the brightest stars if the stars are enabled and visible in the current view. If two stars are close together, only the brightest will be labeled; so as to prevent overlapping. Note for Bayer&Flamsteed Ids, the Flamsteed Id (i.e.: Tau 37) is only shown if no Bayer Id exists for the star.


Options Constellation Labels
Options Constellation Labels:

Options Constellation Names/Codes/Common Names:

This enables labels to be displayed in gold for the displayed star constellations. The names will be displayed centered within the visible stars of each constellation. If no stars of a particular constellation are displayed, the constellation name will not be displayed.

Since the constellation names can easily clutter the display, Constellation Codes enables the abbreviated constellation code name to be displayed instead of the full constellation name. As above, if no stars of a particular constellation are displayed, the constellation code will not be displayed.

Common Names can optionally be displayed, which are English equivalent names for the constellations.

These labels may overlap.


Options Solar System Labels
Options Solar System Labels:

Options Solar System Objects Names:

This enables labels to be displayed in red for the planets, the sun and the moon. These will be displayed above the object if the object is enabled and visible in the current view. If two objects are close to each other in the display, the names may overlap each other.


Options Deep Sky Labels
Options Deep Sky Labels:

Options Deep Sky Object Names / Messier Numbers / NGC Numbers:

This enables labels to be displayed in magenta for the deep sky objects (galaxies/nebula/ etc.). These will be displayed above the objects if the objects are enabled and visible in the current view.

If two objects are close to each other in the display, the names may overlap each other.


Options Altitude Lines
Options Altitude Lines:

This will draw labeled blue altitude lines at 15 degree intervals parallel to the horizon. The horizon is shown with a dashed line. Altitude indicates the angle above/below the horizon. The zenith (Z) and nadir (N) are shown as well (in blue).


Options Azimuth Lines

This will draw labeled blue azimuth lines at 15 degree intervals perpendicular to the horizon. Azimuth lines indicate the compass directions (i.e.: North, South, East, West).


Options Compass
Options Compass:

This will draw the compass coordinates (the azimuths) in blue at the horizon (N/S/E/W).


Options Declination Lines
Options Declination Lines:

This will draw labeled cyan declination lines at 15 degree intervals from the celestial equator. The Celestial Equator is shown with a dashed line. The north (N) and south (S) celestial poles are shown as well (in cyan).


Options Right Ascension Lines
Options Right Ascension Lines:

This will draw labeled cyan right ascension lines at 15 degree (1 Arc Hour) intervals perpendicular to the celestial equator. The Equinoxes are shown using a dashed line.


Options Ecliptic Line
Options Ecliptic Line:

This will draw the ecliptic dashed in yellow. This corresponds to the path of the orbit of the sun during the year and it crosses the celestial equator at the vernal(spring) equinox and the autumnal(fall) equinox.


Options Ecliptic Longitude Lines
Options Ecliptic Longitude Lines:

This will draw labeled yellow ecliptic longitude lines at 45 degree intervals, and hence corresponds to the position of the sun on the first day of spring - equinox (0 degrees), mid-spring(45), first day of summer - solstice (90), mid-summer(135), first day of autumn - equinox(180), mid-autumn(225), first day of winter - solstice (270) and mid-winter(315). The north (N) and south (S) ecliptic poles are shown as well (in yellow).


Options CrossHair
Options CrossHair:

This will draw a red crosshair through the centre of the screen as an aid in identifying the centrepoint of the current view and for determining directions. The arrow points to the North Celestial Pole.


Options FontSize
Options FontSize:

This allows the user to increase or decrease the size of labels used on the display.


View Towards Fixed Direction
View Towards Fixed Direction:

This dialog box allows you to set your view towards a fixed viewing direction using horizontal coordinates.

This dialog box is accessible from the View Towards menu or by clicking on the Alt/Azi data area.

Altitude may be entered in degrees and minutes (i.e.: 45 30), or as decimal degrees (i.e.: 45.5, or 45,5). Convenience buttons are provided to set the direction towards the zenith (straight up, Alt 90), the horizon (normal, Alt 0), or the nadir (straight down, Alt -90), and convenience scrollers are provided to increase and decrease the altitude by five degree increments.

Azimuth may be entered in degrees and minutes (i.e.: 45 30), or as decimal degrees (i.e.: 45.5, or 45,5). Convenience buttons are provided to set the direction towards north (Azi 0), east (Azi 90), south (Azi 180), or west (Azi 270), and convenience scrollers are provided to increase and decrease the azimuth by five degree increments.

The chosen fixed direction will be locked in the centre of the display.

- Viewing towards the horizon, the horizon appears as a straight horizontal line with the stars above it.

- Viewing towards the zenith (straight up), the stars appear in the centre of the display, and the horizon appears as a circle around them. You can imagine that your feet are pointing in the direction of your chosen azimuth.

- Inversely, viewing towards the nadir (straight down, if you could see through the earth) the earth appears in the centre and the stars appear around the horizon.


View Towards Equatorial Coordinate
View Towards Equatorial Coordinate:

This dialog box allows you to set your view towards and lock onto a specific celestial coordinate using equatorial coordinates.

This dialog box is accessible from the View Towards menu or by clicking on the Rta/Dec data area.

Declination may be entered in degrees and minutes (i.e.: 45 30), or as decimal degrees (i.e.: 45.5, or 45,5). Convenience buttons are provided to set the view towards the north celestial pole (Dec 90), the celestial equator (Dec 0), or the south celestial pole (Dec -90) and convenience scrollers are provided to increase and decrease the declination by five degree increments.

Right ascension may be entered in hours and minutes (i.e.: 5:30), or as decimal hours(i.e.: 5.5, or 5,5). Convenience buttons are provided to set the view towards the vernal equinox (Rta 0h), the summer solstice (Rta 6h), the autumnal equinox (Rta 12h), or the winter solstice (Rta 18h), and convenience scrollers are provided to increase and decrease the right ascension by 20 minute (five degree) increments.

The chosen celestial coordinate will be locked in the centre of the display. This means that the same stars will remain in the center of the display, and the viewing direction will be constantly adjusted if required.


View Towards Ecliptic Coordinate
View Towards Ecliptic Coordinate:

This dialog box allows you to set your view towards and lock onto a specific celestial coordinate using ecliptic coordinates.

This dialog box is accessible from the View Towards menu or by clicking on the ELat/ELng data area.

Ecliptic latitude may be entered in degrees and minutes (i.e.: 45 30), or as decimal degrees (i.e.: 45.5, or 45,5). Convenience buttons are provided to set the view towards the ecliptic north pole (ELat 90), the ecliptic (ELat 0), or the ecliptic south pole (ELat -90) and convenience scrollers are provided to increase and decrease the ecliptic latitude by five degree increments.

Ecliptic longitude may be entered in degrees and minutes (i.e.: 45 30), or as decimal degrees (i.e.: 45.5, or 45,5). Convenience buttons are provided to set the view towards the vernal equinox (ELng 0), the summer solstice (ELng 90), the autumnal equinox (ELng 180), or the winter solstice (ELng 270), and convenience scrollers are provided to to increase and decrease the ecliptic longitude by five degree increments.

The chosen celestial coordinate will be locked in the centre of the display. This means that the same stars will remain in the center of the display, and the viewing direction will be constantly adjusted if required.


View Towards Object
View Towards Object:

This dialog allows you to chose an object to view towards and lock onto. For the solar system objects, a static  image of the object will also be displayed in the data area.

This dialog is accessible from the View Towards menu or the image portion of the data display area.

1) First select the type of object to view toward:

a Star:

by common name, by Bayer Id number, by Flamsteed Id number, or by Yale Bright Star catalogue number.

(The brightest star in) a Constellation:

by name or common name.

a Solar System object:

by common name.

a Deep Sky Object:

by common name, by Messier Catalogue (M) number, or by New General Catalogue (NGC) Number.

2) Then select the required object from the popdown list:

The popdown list contains the brightest objects of that type. Objects currently disabled, or that cannot be seen at the current specified magnitude limits are greyed, but may still be selected. Click on an object, select OK and the view will turn towards and lock onto the chosen object. You may need to enable the object, or zoom in to see it in the projection.

The solar system objects have integrated images associated with them. If the object you select has an image available, it is shown in the data area as well.

Once an object is selected, the view altitude and azimuth, and celestial coordinates, will be modified in order to keep the projection facing the specified object.


Terrestrial Coordinates
Terrestrial Coordinates:

Positions on earth are measured in latitude and longitude (Lat & Lng).

Latitude indicates how far north or south a position is from the equator, Lat 0. The geographic north pole is 90 degrees north and the south pole is 90 degrees south.

Longitude indicates how far east or west a position is from the prime meridian, Lng 0, which runs through Greenwich, London, England. Positions east of Greenwich are in the eastern hemisphere and have east longitudes. Positions west of Greenwich (the Americas, for example) are in the western hemisphere, and have west longitudes.


Ecliptic Coordinates
Ecliptic Coordinates:

Celestial coordinates are sometimes specified in ecliptic latitude and longitude (ELat & ELng), especially for the planets and objects near the sun.

Ecliptic latitude 0 (the ecliptic) corresponds to the path of the sun against the background of stars in it yearly motion as seen from earth. Ecliptic latitude is measured north and south from the ecliptic.

Ecliptic longitude corresponds to the position of the sun on this path. ELng 0 is the position on the first day of spring, the vernal equinox; ELng 90 is its position at the summer solstice; ELng 180, the autumnal equinox; and ELng 270, the winter solstice.

The ecliptic poles indicate the rotational axis of the earth's yearly orbit around the sun.


About MyStars!

This dialog shows the copyright and version information for MyStars!

This dialog is accessible at startup (until the program is registered), from the help menu, or by clicking on the MyStars! logo in the data display area.

If the application is not registered, you can press the REGISTER button which allows you to register the product, or you can press CONTINUE UNREGISTERED, which allows you to run the program unregistered in order to evaluate it.

Once the application is registered the REGISTER, and CONTINUE UNREGISTERED buttons do not show.


Options Status Bar
Options Status Bar:

Selecting this option adds a status bar to the bottom of the screen, describing in more detail the menu items as they are selected, and indicating the state of calculation. Don't forget that you may access menu items even when computations are underway (WORKING...). It is not necessary to wait until it says WAITING... .

The mouse unfortunately is inoperative while the system is BUSY PAINTING.


Horizontal Coordinates
Horizontal Coordinates:

Fixed directions towards the sky, from the point of view of an individual on earth, are often measured in altitude and azimuth (Alt & Azi).

Altitude indicates how far something is above or below the horizon. Straight up (towards the zenith) is Alt 90 degrees. Towards the horizon is Alt 0 degrees. Straight down (towards the nadir) is Alt -90 degrees.

Azimuth indicates the compass direction. North is Azi 0 degrees; East, Azi 90 degrees; South, Azi 180 degrees; and West, Azi 270 degrees.

Generally, as objects appear to move through the sky, their altitude and azimuth change, rising from the east and setting in the west.


Register

This dialog allows you to enter your registration number.

This dialog is accessible from the About MyStars! dialog until the product is registered.

If you have been sent a registration number, type it in the registration number box and press OK.

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Image Credits

Venus:	JPL, NASA P-45186 Magellan

Mars:	HST Photo STScI-PRC95-17B

Philip James (Univ. of Toledo)

Steven Lee (Univ. of Colorado)

NASA, STScI

Jupiter:	JPL, NASA P-20957C Voyager

Saturn:	JPL, NASA P-23883C Voyager

Uranus:	JPL, NASA P-29478 Voyager

Neptune:	HST

David Crisp (JPL)

Heidi Hammel(MIT)

STScI


Equatorial Coordinates
Equatorial Coordinates:

Celestial coordinates are usually specified in right ascension and declination (Rta & Dec). They are an extension of terrestrial coordinates into the sky.

Declination corresponds to terrestrial latitude. The point in the sky straight up from Lat X is always Dec X.

Right ascension corresponds to terrestrial longitude, except that Rta 0, is a fixed position in the stars and corresponds to the position of the sun on the first day of spring, the vernal equinox. As the earth rotates, the right ascension straight up from any longitude on earth increases as we move under the stars at that right ascension. Rta is measured in 'hours' as opposed to degrees.

The celestial poles indicate the axis of the earth's daily rotation.