HRC PR200L

Important Notes

These files are meant to be used together. The sensitivity curve was derived using observations of two white dwarf standards in a +/-0.5 arcsec (+/-19 pixels) wide extraction box. Note that the dispersion of the prism varies with wavelength in a highly non-linear fashion. The current wavelength calibration is based on observations of a planetary nebula and a QSO with lines between 1909Å and 3500Å. The wavelength calibration is estimated to be accurate to about 0.5 pixels over this range. At longer wavelengths the reliability decreases rapidly, affecting not only the wavelength scale but also the flux calibration. Users should also be aware that red light may scatter from the red to the blue end of the spectrum, leading to possible systematic errors in the flux calibration for red objects. This effect is at present poorly quantified.

The definition of the PR200L aperture was changed on Nov 8th, 2004. Separate configuration files are available for observations made before and after this date. The configuration files only differ in the constant terms in the trace- and wavelength descriptions, i.e. the general form of these relations is assumed to be unchanged.

It is very important that aXe v. 1.42 or later be used for the extraction of prism spectra. The aXe pages contain the latest version of aXe as well as sample test data and a sample script to perform the extraction

More details about the PR200L calibrations are available here