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GeoLat - The geodetic latitude of the observer   

Description:
This attribute specifies the geodetic latitude of the observer, in degrees. Together with the GeoLon, Epoch, RefRA and RefDec attributes, it defines the Doppler shift introduced by the observers diurnal motion around the earths axis, which is needed when converting to or from the topocentric standard of rest. The maximum velocity error which can be caused by an incorrect value is 0.5 km/s. The default value for the attribute is zero.

The value is stored internally in radians, but is converted to and from a degrees string for access. Some example input formats are: "22:19:23.2", "22 19 23.2", "22:19.387", "22.32311", "N22.32311", "-45.6", "S45.6". As indicated, the sign of the latitude can optionally be indicated using characters "N" and "S" in place of the usual "+" and "-". When converting the stored value to a string, the format "[s]dd:mm:ss.s" is used, when "[s]" is "N" or "S".

Type:
String.

Class Applicability:
SpecFrame
All SpecFrames have this attribute.



next up previous
Next: GeoLon - The geodetic longitude of the observer
Up: AST Attribute Descriptions
Previous: Gap(axis) - Interval between major axis values of a Plot

AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. Warren-Smith & D.S. Berry
30th April 2003
E-mail:ussc@star.rl.ac.uk

Copyright (C) 2003 Central Laboratory of the Research Councils