Select the input coordinate system (default is equatorial) and equinox if applicable (default is J2000). Enter the epoch of observation if applicable and known (between AD 1500.0 and AD 2500.0, in decimal years).
Enter the cordinates (in sexagesimal units or decimal degrees) and position angle (optional, default is 0 in decimal degrees).
Examples of input coordinates:
- 09h55m52.7s +69d40m46s
- 09:55:52.7 +69:40:46
- 09 55 52.7 +69 40 46
- 148.969687d 69.679383d
Select the output coordinate system and equinox if applicable, then hit "Go".
More information can be found here.