Astronomical calculations

This site contains low precision formulas, algorithms and some code for calculating the equatorial, ecliptic and horizon coordinates and the rise, transit and set times of the Sun, Moon and the planets. You will also find some information on plotting star charts, horizon charts and planispheres; all based on the polar and equatorial stereographic projection.

Disclaimer: The methods in this Web site are low precision and are not suitable for celestial navigation, occultation prediction, eclipse prediction or similar circumstances where high accuracy is needed. Thanks to people who have pointed out errors - some are bound to remain so check results against known sources before trusting the methods here.

Latest Addition | VBA module that defines 'user functions' for finding the sunrise/set and times of the three twilights for any latitude. - Added 2nd Jan 2003

Coordinates | Alt Az from Ra and DEC | Precession | Sidereal time |
Charts | Plotting a planisphere | Plotting an horizon sky chart | Plotting a star chart
Planets | Finder tables | charts ( corrected! ) | Circular orbits | Elliptical orbits | QBASIC elliptical | Kepler's equation
Sun | Position to 0.01 deg | Rise and set | Javascript: rise and set for any latitude (newish) | Excel: VBA module for sunrise / set and twilights (new) |
Moon | 0.3 deg | 4 arcmin | 10 arcsec | Rise and set | Libration | Javascript | C
Other satellites | Galilean | Saturn rings
Tools | VBA | Euler | Excel spreadsheet with examples of most methods (no VBA)
About these pages | Who for | How made | Author
Feedback | form: make comments and suggestions |
Latest link | Excel spreadsheets by Thomas Kraus. Thomas has implemented a superb range of Excel spreadsheets that include excellent diagrams and the full planetary series.- added 17th Dec 2002

Other Web sites (I found these useful - you might too - all checked 29th Dec 02) | Paul Schlyter's calculation site (note the new domain) | 2003 Astronomical Almanac from Kiev | Excel spreadsheets for sun/moon rise (thanks to Fred for reference) | Celestial navigation manual also Javascript pages for navigation | Notes on spherical astronomy | Sky View Cafe | Sky Calc C code (John Thorstensen) | UNSO Data Services | Sun and Moon rise | ephemeris generator | Galilean moon events | ICE | Meridian | Mooncalc | Clementine Skimmer | The Electric Astrolabe | IntelliCAD click on the 'free download' icon | WinTopo | Bill Arnett's Planetarium Software page | Dan's Astronomy Software | Astronomy notes | Simple planisphere | Online 'astrolabe' templates | Monthly Sky Maps | Constellation guides | Tmoon Delphi component with moon position code | Celestial navigation javascripts by Henning Umland | Delta-T values new definition Delta T = 32.184 s + (TAI - UTC) - (UT1 - UTC) where (TAI - UTC) is number of leap seconds (32s until June 03) and (UT1 - UTC) is listed starting in column 59 of file finals.daily for 90 days of measurements and 90 days of predictions |

Keith Burnett
29th Dec 2002 (rained ALL day)