AIRINDEX

Name

airindex

Purpose (one Line)

Compute the real part of the refractive index of air.

Description

This function is based on the formulas in Filippenko, PASP, v. 94,
pp. 715-721 for the index of refraction of air. The conversion from
relative humidity to vapor pressure is from the Handbook of Chemistry
and Physics.

Calling Sequence

n = airindex(wave,pressure,temp,relhum)

Inputs

wave - wavelength of light, in microns
pressure - atmospheric pressure in mm of Hg
temp - atmospheric temperature in degrees Celcius
relhum - Relative humidity (in percent)

Outputs

return value is the index of refraction for the input conditions.

Revision History

Written by Marc W. Buie, STScI, 1991/02/28
1997/03/03, MWB, changed name from REFRAC, changed to relative humidity
2005/08/23, MWB, fixed bug in one internal equation