The MAXCLOCK webpage


Software Description

MAXCLOCK is a high-precision digital astronomical clock.  It displays the following data on your computer screen:
Coordinates may be referenced to mean dynamic equinox and ecliptic of date or to FK5.  The inclusion of nutation and/or aberration is freely selectable.
Time data are displayed for ITRF Greenwich zero meridian.  Solar and sidereal times are also displayed for any other freely user-selectable location anywhere on planet earth, e.g. for your home observation site.

Other features:

Overall accuracy (near epoch 2000):

Position of Sun:                                                     0.006 arcsecs (full VSOP87 algorithm)
Distance to Sun:                                                    3.0x10-8 AU
Position of Moon:                                                  0.05 arcsecs (truncated ELP2000-82B-algorithm)
Distance to Moon:                                                  3.0x10-8 of nominal distance
Mean time values:                                                  determined only by user-supplied geographic longitude accuracy
Apparent sidereal time:                                         microsecond domain (planetary perturbations)
Apparent solar time and equation of time:       millisecond domain (due to positional accuracy of Sun)


MAXCLOCK will run on any PC / XT / AT (x86, x88, x286, x386, x486, Pentium, with or without math coprocessor),  under any DOS or WINDOWS operating system. 
A textmode-only black & white screen and 390 kB RAM (800 kB RAM under WINDOWS VISTA / WINDOWS 7 / WINDOWS 8 / WINDOWS 10) will suffice.
(For automatic clock mode, a working system clock and a x286 processor, preferably with coprocessor, is required at minimum.)


MAXCLOCK is distributed for free, either per e-mail directly by the author (including tailored configuration file) or per download from the webpage.

Author & Copyright:

Udo Mark
Meisenweg 4,  85667 Oberpframmern,  Germany
E-Mail: admin at

Screenshot example:


Back to MAXCLOCK main page    Back to site index    last revised: 2019-02-28