Coordinate Conversions

Comments:

  • All input coordinates are in DEGREES except when entering Celestial coordinates---"Longitude" becomes "Right Ascension" and MUST be entered in HOURS as appropriate for the specified format.
  • The "Coordinate Format" element controls both input and output formats. If "Deg:Min:Sec" is selected, both input coordinates must be in this format.
  • A small error creeps into the calculations when working with epochs earlier than 1550; this error increases as the epoch becomes earlier. At J0000, this error is about 2.2 arcseconds. It can be illustrated by entering RA/DEC of 0,0 and setting both the input and output epochs to zero; in this case, the RA/Dec and Ecliptic Long/Lat should all be zero but are not.
A service of the HEASARC and of the Astrophysics Science Division at NASA/GSFC
Goddard Space Flight Center, National Aeronautics and Space Administration
HEASARC Director: Dr. Alan P. Smale
LAMBDA Director: Dr. David T. Chuss
NASA Official: Dr. David T. Chuss
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