Sun and Moon Almanac  V1.51  for the Years 1975-2015
Copyright © 1999-2002 Henning Umland

y m d h m s
 Date:             Time (UT1):                
GHA Dec SD HP Equation of time
Sun:
Moon:   Illum. 
Aries:


Description:
This computer almanac for sun and moon is based upon formulas published in Astronomical Algorithms by Jean Meeus.

The almanac is valid through 2015. Beyond, the calculated data would gradually become inaccurate since a precise long-term prediction of Delta T (difference between Terrestrial Dynamical Time and UT1) is impossible. All computer almanacs using UT1 have this problem. The program calculates Delta T by linear interpolation between values measured or predicted by the IERS Rapid Service / Prediction Center. Later versions of this software will contain updated values for Delta T.

The program regards any blank dialog box in the time input field as zero. A missing year, month, or day will result in an error message (program must be restarted). The number of the year must be entered in 4-digit format.

A "(+)" behind the value for the moon's illumination indicates an waxing moon, a "(-)" a waning moon.

Accuracy:
GHA and Dec of the sun: approx. ±0.02´
GHA and Dec of the moon:    approx. ±0.15´
GHA Aries:    approx. ±0.01´
HP and SD: approx. ±0.01´
Equation of time: approx. ±0.2s

GHAAries refers to the true equinox of date.

This program is freeware and may be copied and distributed in unmodified form and on a non-profit basis. For your private use, feel free to modifiy the source code according to your requirements. Any commercial distribution requires the author's permission.

Henning Umland      N 53° 20.6´   E 9° 52.0´       e-mail: mail@celnav.de

Check this web site for updated versions: http://www.celnav.de

Warranty disclaimer:
Results obtained with this program have been cross-checked with Multiyear Interactive Computer Almanac 1.5 by USNO. However, the program is still experimental and may contain errors leading to unexpected results in rare cases. Use at your own risk.

Warning:
Editing and modifying the JavaScript code may lead to unpredictable results. Users who are not familiar with JavaScript and calculations of ephemerides are strongly advised to leave the code unchanged.