The MAXCLOCK webpage
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.
Civil date & time, day number in the year;
Julian date and modified Julian date both in terms of ephemeris time ET (TT) and
universal time UT1;
Delta-T, the difference between ET and UT1;
Mean solar time, apparent solar time, equation of time;
Mean sidereal time, apparent sidereal time, equation of equinoxes;
Geocentric ecliptical and equatorial coordinates of Sun and Moon;
Constellation and zodiac sign for the Sun;
Constellation, zodiac sign, phase, appearance, and illuminated fraction of the Moon;
Elongation between Sun and Moon;
Earth distance to Sun and Moon;
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
The program uses the internal clock of the computer and an easy-to-edit configuration file only.
The screen display has manual and automatic mode, update interval in automatic mode may be selected
between one and 60 seconds.
Timely announcements are issued when Moon phases, solstices, or equinoxes are nearing.
Nutation and precession are modelled with conventional paradigm using IAU 1980 lunisolar
series. Various options for equation of equinoxes are available:
classical or IAU equation, with or without Herring's and Vondrak's corrections.
Two obliquity polynomials are selectable.
Enables computations for freely user-supplied date & time (typed through keyboard or read from file, with appropriate internal evaluation of ephemeris time). Julian and Gregorian calendar are implemented, covering a total timespan from 9999 BC to AD 9999. Thus, compilation of time-lapse-sequences is possible.
The internal ephemeris time model uses latest results from F.R. Stephenson, L.V. Morrison, J. Chapront,
M. Chapront-Touzé, and G. Francou. It is adjusted for most actual tidal acceleration
and incorporates high-precision Delta-T values (derived from IERS C04 data) up to date of issue.
The model may be modified by user-supplied Delta-T values.
DUT1 is freely selectable by user.
The output may also be directed to a protocol file.
Acoustic time signalling (time beeps) can be selected.
The package comes with detailed user instructions, as well as information about algorithms,
accuracy, and literature references.
Overall accuracy (near epoch 2000):
Position of Sun:
0.006 arcsecs (full VSOP87 algorithm)
Distance to Sun:
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:
Meisenweg 4, 85667 Oberpframmern, Germany