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: JPL HORIZONS service & IMCCE service hosted through ESO Moving Targets Procedures page
  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. The IMCCE service provides the same data in PAF format that needs to be used for ESO Observing Blocks preparation.
• 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.
• JD converter: Converts civil date to julian date and reverse

Position, Airmass, Extinction

• Airmass Calculator
  This tool provides hourly airmass based on site, date, and object coordinates information in tabular format. Additionally, it will compute the parallactic angle as well as heliocentric-barycentric corrections. A Parallactic angle calculator for DFOSC instrument on the 1.54m Danish telescope can also be used to compute parallactic angle for any observation. 
• Object Visibility - STARALT (ING)
  draw the airmass curves for a list of objects, for a given night
• Extinction coefficients for La Silla (old Danish 1.54m page)
• Differential atmospheric 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.

ETCs and Units Conversion

• Exposure Time Calculators
• ESO's SkyCalc (the Sky Model calculator, that also includes an Almanac)
• Magnitude/Flux Density Converter (from Spitzer Science Center)