Data Services

Computing the times of celestial phenomena such as sunrises and sunsets is just one practical application of astronomy. Image by Susan Stewart, USNO.

Rise/Set/Transit/Twilight Data

• Complete Sun and Moon Data for One Day
• Table of Sunrise/Sunset, Moonrise/Moonset, or Twilight Times for an Entire Year
• Rise/Set/Transit Times for Major Solar System Objects and Bright Stars
• Duration of Daylight/Darkness Table for One Year

Phases of the Moon

• Dates of Primary Phases of the Moon
• Fraction of the Moon Illuminated
• What the Moon Looks Like Today

Eclipses and Transits

• Eclipses of the Sun and Moon
• Solar Eclipse Computer
  Computes circumstances for selected solar eclipses at any given location.
• Lunar Eclipse Computer
  Computes circumstances for selected lunar eclipses at any given location.
• Recent and Upcoming Transits of Mercury and Venus
• Transit Computer
  Computes circumstances for selected transits of Mercury and Venus at any given location.

Positions of Selected Celestial Objects

• Altitude and Azimuth of the Sun or Moon During One Day
• Topocentric Configuration of Major Solar System Bodies
  Provides tables of low precision topocentric position data for the Sun, Moon, and major planets.
• Geocentric Positions of Major Solar System Objects and Bright Stars
  Provides high precision geocentric position data for the Sun, Moon, major planets and selected bright stars.
• Topocentric Positions of Major Solar System Objects and Bright Stars
  Provides high precision topocentric position data for the Sun, Moon, major planets and selected bright stars.

Synthetic Views of the Earth and Solar System Bodies

• Day and Night Across the Earth
  Creates synthetic views of the Earth's surface (in grayscale or color) for any date and time.
• Apparent Disk of Solar System Object
  Creates a synthetic image of the telescopic appearance of the Moon or other solar system object for specified date and time.

Dates

• Earth's Seasons - Equinoxes, Solstices, Perihelion, and Aphelion 2000-2020
• Spring Phenomena, 25 BCE to 38 CE
• Julian Date Conversion

Celestial Navigation

• Celestial Navigation Data
  Provides computed altitudes and azimuths and other data for an assumed position and time.
• Navigational Star Chart

Miscellaneous

• Astronomical Almanac Online
  Provides complementary data to the printed Astronomical Almanac.
• International Celestial Reference System (ICRS) - Important links relating to the implementation of the ICRS
• Occultations of Stars by Asteroids (International Occultation Timing Association)