DIFREF

Name

difref

Purpose (one Line)

Compute amount of atmospheric refraction relative to 5000 Angstroms.

Description

this function is based on the formulas in Filippenko, PASP, v. 94,
pp. 715-721 for the index of refraction of air (routine REFRAC).

Calling Sequence

ans = difref(wave,pressure,temp,water,zenith)

Inputs

wave - Wavelength of light, in microns.
pressure - Atmospheric pressure, in mm of Hg.
temp - Atmospheric temperature, in degrees C.
water - Water vapor pressure, in mm of Hg.
zenith - Angle from the zenith, in radians.

Optional Input Parameters

Keyword Parameters

Outputs

Returns the amount of differential refraction in arcseconds.

Common Blocks

Side Effects

Restrictions

Procedure

Modification History

Written 1991 Feb, by Marc W. Buie, Lowell Observatory