The "Coordinate Format" element controls both input and output formats. If
"Deg:Min:Sec" is selected, both input coordinates must be in this format.
Epochs should be entered as a number: 2000 or 1950. FK5 precession coefficients are used,
as specified in the "Astronomical Almanac Explanatory Supplement", 1992, p104, Table 3.211.1.
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.