Centro Astronómico Hispano Alemán

- Atmospheric refraction and slit transmission -

Atmospheric Parameters

Temp.C Hum.% Press.HPa
Zenith dist. Airmass

Seeing (")
Wavelength (µ) 1
Wavelength (µ) 2

Length("), Width(")
Position Angle() *

Air refr.Index Refraction (") Slit transmisssion **

* Position angle of the slit relative to vertical when pointing to the star. To have the slit aligned vertically, it has to be rotated with an angle equal to the parallactic angle.
** We assume that the star is centered in the slit with the image of wavelength 1.
*** The formulae used in this calculator are described here.
Santos Pedraz Marcos
Last modified: Mon Jun 9 09:53:55 GMT 2003