CREDITS

Sidereal v1.0
Authored By: Richard W. Parker
February 6, 1997

DISCLAIMER

 ******************************************************************************
 * Software and documentation (c) Copyright 1997 RezCo.  All rights reserved. *
 *                                                                            *
 * Sidereal may be distributed freely for non-commercial purposes.  This      *
 * documentation should be included in an unmolested form as part of such     *
 * redistribution.                                                            *
 *                                                                            *
 * This software is provided as-is, without any warranties expressed or       *
 * implied.  Under no circumstances shall the authors be liable for any       *
 * unpleasant consequences of the use of this software.                       *
 ******************************************************************************

DESCRIPTION

Sidereal is a small time utility for the Newton that automatically computes
and displays the local mean sidereal (astronomical) time based upon the home
location that is set in the Time Zones application, and the time from the
Newton's internal clock.  Sidereal should work with all versions of the Newton
OS and requires approximately 6K of storage.

USAGE

Tap on the Sidereal icon in your Extras drawer to bring up the sidereal clock
display.  This display shows the current local mean sidereal time (LMST) in hours
and minutes, and updates automatically.  By setting your "I am here" location in
the Time Zones application and your local time in the Clock application,
Sidereal will compute and display the appropriate LMST.  Remember: the accuracy
of Sidereal's computations is directly based on the accuracy of your settings
in Time Zones and Clock.

Tap on the "i" button to see the credits and version number view (tap the "X"
to close this view and return to the sidereal clock display).  Tap on the "X"
button to close Sidereal.

EXPLANATION

Our watches and clocks display "Solar" time: the measurement of the motion of
the Earth with respect to the Sun.  Solar time is not very accurate, and is
constantly being adjusted to make it more "convenient" for humans and their
activities (e.g. Daylight Savings Time).  It is because of this that
astronomers measure time in a more absolute scale called Sidereal Time: the
measurement of the motion of the Earth with respect to the background stars.

The stars and constellations rise and set at different Solar times throughout
the year, but they always rise and set at the same Sidereal time.  This fact
is important, because it means that no matter what day, month, or year it is,
a given astronomical object will always be in the same place in the sky at the
same Sidereal time.

The "Local Mean Sidereal Time", or LMST, is the Sidereal time that is directly
overhead at a given location.  This is based upon the longitude (or East/West
position) of the observer on the Earth, and the current Greenwich Mean Solar
Time (or what is called "Universal Time").  So why would you want to know your
LMST?  You would want to know your LMST because it tells you which objects
are crossing the "Meridian", or line that passes through the Zenith (or point
directly overhead) and connects the North and South poles, at that moment.
All that you need to know is the Sidereal Time value for the object that you
are interested in; this value is called "Right Ascension" in star catalogs and
astronomy references.

If you look up the star "Betelgeuse" (a red supergiant star in the constellation
of Orion the Hunter), you will find that its Right Ascension is:
		Right Ascension: 05h 55.2m
Knowing the Right Ascension of an object and your LMST will tell you where the
object is in relation to that imaginary Meridian line directly overhead.  For
example, if your LMST is 03:55, you know that Betelgeuse is two hours East of
the Meridian (from horizon to horizon is 12 hours, so 2 hours would be 30
degrees).  When your LMST is 05:55, Betelgeuse will be crossing the Meridian,
and therefore will be at its highest point in the sky; this would be the
best time to view Betelgeuse (assuming that it was actually dark outside).

So, armed with your Newton, the Sidereal program, and a good star atlas, the
entire universe is open to you!

REGISTRATION

Sidereal is "shareware", so if you find that it is useful to you (or just
neat to look at) please register by sending your email address along with
a check, money order, or cashier's check:
	Payee        : Richard Parker
	Shareware Fee: US $5.00
	Address      : P.O. Box 1355
	               South Pasadena CA 91031-1355
	               U.S.A.
All registered users will receive any updates made to Sidereal absolutely
free, and will also gain access to free technical support via email.

FEEDBACK

Comments, criticisms, and bits-o-humour are welcome!  Please email them
to me at: rwp@primenet.com

OBTAINING SIDEREAL

Sidereal is available from RezCo's Official Web Site:
<http://www.primenet.com/~rwp/rezco/index.html>