differentialRefraction

lsst.afw.coord.differentialRefraction(wavelength, wavelengthRef, elevation, observatory, weather=None)

Calculate the differential refraction between two wavelengths.

Parameters:

wavelength : float

wavelength is in nm (valid for 230.2 < wavelength < 2058.6)

wavelengthRef : float

Reference wavelength, typically the effective wavelength of a filter.

elevation : lsst.geom.Angle

Elevation of the observation, as an Angle.

observatory : lsst.afw.coord.Observatory

Class containing the longitude, latitude, and altitude of the observatory.

weather : lsst.afw.coord.Weather, optional

Class containing the measured temperature, pressure, and humidity at the observatory during an observation If omitted, typical conditions for the observatory’s elevation will be calculated.

Returns:

differentialRefraction : lsst.geom.Angle

The refraction at wavelength minus the refraction at wavelengthRef.