Calibration Access and Data Handbook
Previous: Ground calibration
EFFAREACORR correction factors are assumed to result from two effects
that are analysed with a combination of observations of power-law spectra, particularly of Mkn421,
and sources assumed to be constant, namely RXJ1856.6-3754 and the Vela PWN, in which the observed changes
are due to changes in absorption by the contamination layer.
The power-law reference source, currently Mkn421, and the contamination reference source, RXJ1856.6-3754,
are both observed twice per year, the Vela PWN once per year as a contamination control.
- wavelength-dependent effective area correction;
- absorption by contamination on the CCD surfaces.
EFFAREACORR RGS-pn rectification factors result from more complex mechanisms and therefore need
careful consideration before use. The factors are derived from spectral analysis of a number of sources in the