A celestial position may be passed in different coordinate systems (B1950, J2000 or Galactic) or can be the position of an object.
coordinates: The first letter of the string may be used to specify
the coordinate system. B for B1950, J for J2000, G for Galactic. If no system
is given, B1950 is assumed by default.
Equatorial coordinates may be passed in decimal or sexagesimal "free" format.
In decimal format, the coordinates are given as two floating numbers and the
right ascension may be given in hours or degree. To specify it is in degree
it must be followed by "d", "deg" or "degree". No specification or "h" is
interpreted in hours.
Galactic coordinates must be given in decimal degrees.
Object position: A celestial position may be given as a name,
for example M81 (it may be prefixed with an o: for a better clarity).
To precise it is the position of an object in NED or in Simbad, it may be
written: ned:M81 or simbad:M81
Valid examples:
121314+122025, B1950 position (default is B1950 if no system is given) b 12 13 +12 20, B1950 position J 12h 20 m 30.00 s -33 d 14 m 10 s, J2000 position G 172.0 -12., Galactic coordinates NGC4486, position of a named object ned:3C273, position of an object resolved by NED simbad:vega, position of an object resolved by Simbad