The UMARK website

Some useful links when working with MAXCLOCK :

Astronomical timekeeping and Earth orientation (Delta-T,  DUT1, etc.)

• IERS Earth orientation data (& explanatory notes), by USNO
• IERS Earth orientation data and searchable database (& explanatory notes), from Paris Observatory
• IERS Earth orientation data, from IERS
  
  
• Introductions to timescales:   by Steve Allen, Univ. of California   by Paul Schlyter  
• Delta-T tutorial, by R.H. van Gent
• Delta-T tutorial, by Felix Verbelen
• Delta-T overview, history, and predictions, by USNO
• Overviews on UTC leap seconds:   by PTB   by NIST   by BNM-SYRTE   by IERS   by USNO  
• Current & historic values of DUT1:   by NIST   by Paris Observatory  
• Further reading on leap second implications:   by Markus Kuhn, Univ. Cambridge   by Steve Allen, Univ. of California  

IERS official documents

• IERS conventions homepage
• IERS conventions, nicely addressable via the Paris Observatory

Celestial mechanics in general

• Planetary movements: VSOP87 algorithm and data, by P. Bretagnon and G. Francou (ftp link)
• Online ephemeris generator for major & small bodies of the solar system:   by NASA/JPL   by Fred Espenak   
• Online ephemeris generator for solar system bodies and computation of various other celestial phenomena, by IMCCE/BDL, Paris
• Online calculator for any kind of Moon- or Sun-related phenomena, by USNO
• Online data for Moon- or Sun-related phenomena, by H.M. Nautical Almanac Office & RGO

Moon-related phenomena

• Moon orbit: ELP2000-82B algorithm and data, by J. Chapront and M. Chapront-Touzé! (ftp link)
• Tables on lunar phenomena (rising, setting, phases, position, etc., mostly till 2010), by IMCCE/BDL, Paris (ftp link)
• Online calculator for lunar perigee, apogee, and phase, by J. Walker, Fourmilab
• Moon phases catalog 1950-2060, by by Eran Ofek, Wise Obs.

Sun-related phenomena

• Tables on solar phenomena (rising, setting, positions, seasons, etc, partly till 2099), by IMCCE/BDL, Paris (ftp link)
• Equinoxes, solstices, perihelions and aphelions calculated:   by USNO   tabulated, by Fred Espenak   
• A table of perihelions, from 1 to 4000, by Pierpaolo Ricci
• Solstices, equinoxes and seasons, from 1 to 4000, by Pierpaolo Ricci (under sublink "data/seasons")
• Sunrise/Sunset calculator, by NOAA
• Sunrise/Sunset calculator, by USNO
• Sunrise/Sunset calculator, by sunearthtools.com
• Calculator for Sun position (altitude and azimuth through the day with graphic display), by sunposition.info
• Calculator for Sun position (altitude and azimuth through the day with graphic display), by datum-und-uhrzeit.de
• Calculator for Sun position (azimuth projected on satellite imagery), by sunearthtools.com
• Solar eclipses over several millenia, by Fred Espenak and NASA
• The equation of time - for the Earth and other planets, by Pierre Barbier

Calendars

• A table of odd and interesting calendar dates, by Boulder Community Network
• A table of odd and interesting calendar dates, by J.R. Stockton
• Online civil calendar generator (mostly for Germany), till year 2037, by feiertage.net
• Online civil calendar generator, till year 3999, by Steffen Thorsen (timeanddate.com)
• Online calendar converter for various religious and civil calendar systems, by J. Walker, Fourmilab
• Online generator for upcomimg asteroid approaches, by NASA/JPL
• Another generator, providing Sun and Moon data, by Eran Ofek, Wise Obs.
• Link collections with further calendar resources:   by calendarzone.com  

The discussion on the lengths of the tropical and the anomalistic year ...

• Contribution by Kazimierz M. Borkowski, 1991
• Contribution by Segura Gonzalez, 1991
• Contribution 1 by Simon Cassidy, 1996
• Contribution 2 by Simon Cassidy, 1996
• Contribution by Vigdis Hocken

Celestial navigation and fixed stars

• The Online Nautical Almanac, 1950-2050, by Omar F. Reis, tecepe.com
• Online navigation data, by USNO
• Navigational star chart, by USNO
• Delporte's Constellation Boundary Catalogue,  re-edited by Davenhall and Leggett, 1989 (from CDS Strasbourg)
• Constellations and their boundaries, charts, year 1875 and year 2000 numeric data, by Pierre Barbier
• Further links to thematic star catalogues, constellation data, and images, by Bruce MacEvoy, Black Oak Observatory

Geographical coordinates

• A worldwide list of observatory geodetic coordinates with MPC observatory codes (from Harvard-Smithsonian Center for Astrophysics, Cambridge)
• And an interactive map service which delivers numerical coordinates for central Europe (Bundesamt f. Kartographie, Frankfurt)
• The movement of the Greenwich Meridian, by S. Malys et.al.
• Another interactive map service which delivers worldwide coordinates (caltopo.com)
• Another interactive map service which delivers worldwide coordinates (gpsvisualizer.com)
• Another interactive map service which delivers worldwide coordinates with empasis on Bavaria (bayernatlas)
• And Google Earth online

Time zones and legal time

• Online timezone map, by weltzeit.de
• Detailed color timezone maps, from 1997 to 2015, by University of Texas
• And an overview black&white map, as of 2017, by USNO
• Time zone abbreviations, by Steffen Thorsen (timeanddate.com)
• The international date line:   by R.H. van Gent   by USNO  
• Tables on daylight saving time periods in Germany:   1916-1979, by PTB   since 1980, by PTB  
• Daylight saving times worldwide:   by PTB   
• Daylight saving time in the European Union, 2017-2026:   by BNM-SYRTE   
• Daylight saving time in the US:   by USNO  
• Further references on on time notation standards and legislative affairs:  by Markus Kuhn, Univ. Cambridge  
• Frequency tables for time signal stations:   by W. Hepburn   by Klaus Betke, DL4BBL   by shortwave.be   by wikipedia  
• A list of time dissemination services:  by BIPM (FTP link)  

Precision timekeeping

• Atomic & electronic clocks, by Tom Van Baak, www.leapsecond.com

Documents of historical interest

• This section - having been sporadic anyway - has been closed.
  Since historical documents are collected in very numerous places and online libraries nowadays,
  it is warmly recommended to use a conventional internet search engine.

© 2025 Udo Mark

www.umark.de/maxclock_links_e.html   last revised: 2025-08-30