Next / Previous / Contents / Shipman's homepage

4.9. rdaa: Equatorial to horizon coordinates

To find the position in some observer's sky of a celestial object with right ascension RA, and declination DEC, use this command:

rdaa RA±DEC lat lon dt

Right ascension in hours, followed by the signed declination; either “+” or “-” is required as a separator. For the format of hour quantities, see Section 4.4, “Specifying hours on command lines”; for the format of the declination, see Section 4.2, “Specifying angles on command lines”.

lat lon

The next two arguments are the observer's latitude and longitude, respectively; see Section 4.3, “Specifying latitude and longitude on command lines” for the syntax of these arguments.


The date and time of the observation, using the syntax described in Section 4.1, “Specifying dates and times on command lines”.