GIRAFFE Pipeline Reference Manual

Astronomy related Utilities

Functions

cxdouble giraffe_compute_airmass (cxdouble alpha, cxdouble delta, cxdouble lst, cxdouble exptime, cxdouble latitude)
 Compute the airmass for a given pointing direction and observing site.
 

Detailed Description

TBD

Function Documentation

cxdouble giraffe_compute_airmass ( cxdouble  alpha,
cxdouble  delta,
cxdouble  lst,
cxdouble  exptime,
cxdouble  latitude 
)

Compute the airmass for a given pointing direction and observing site.

Parameters
alphaRight Ascension in degrees.
deltaDeclination in degrees.
lstLocal sidereal time in seconds elapsed since sidereal midnight.
exptimeIntegration time in seconds.
latitudeLatitude of the observatory site in degrees.
Returns
The function returns the computed average airmass. In case an error occurred the returned airmass is set to -1.

The function calculates the average airmass for the line of sight given by the right ascension alpha and the declination delta. The latitude in degrees of the observatory site latitude, and the local sidereal time at observation start lst has to be given, as well as the duration of the observation, i.e. the exposure time exptime.

The airmass is computed using the approximations of Young (Young A. T., 1994, "Air mass and refraction", Applied Optics, 33, 1108-1110) and Stetson (Stetson P., 1987, PASP 99, 191).

Definition at line 185 of file giastroutils.c.


This file is part of the GIRAFFE Pipeline Reference Manual 2.12.
Documentation copyright © 2002-2006 European Southern Observatory.
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