Ephemerides and Calculators

The tools and information linked from this page will be useful for all the aspects of observations that are related to the position of the target: their visibility, sun- and moon-rise and -set, ephemerides for Solar System minor bodies, etc.

Ephemerides

• Calculation of Site Sky Ephemerides
  This tool produces a nightime calendar of phenomena for a single site.
• Solar System Ephemerides
  The JPL HORIZONS on-line solar system data and ephemeris computation service provides access to key solar system data and flexible production of highly accurate ephemerides for solar system objects.
• Object Observability
  This tool provides object observability tables based on site, object coordinates and observing period.
• Daily Almanac
  This tool produces almanac data for a single site and for a single date. Provided by courtesy of J. Thorstensen and B. Casey.

Calculators

• Airmasses Calculator
  This tool provides hourly airmasses based on site, date, and object coordinates information. Additionally, it will compute the parallactic angle as well as heliocentric-barycentric corrections.
• Differential athmospheric refraction table for the La Silla and Paranal sites.
  The differential atmospheric refraction is calculated in arcseconds, at an altitude of 2 km, as function of wavelength and airmass. A new calculator is being worked on and will go into the infrared.
• Paralactic angle calculator
  While this tool has specific features for the DFOSC instrument on the 1.54m Danish telescope, it will compute the paralactic angle for any observations.