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Hubble Space Telescope
ACS Performance

HRC PR200L aXe products

To use these calibration products with aXe, copy them into a directory and set your AXE_CONFIG_PATH environment variable to point to that directory.

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

aXe Downloadable files for PR200L

All of the below files are available for download via ftp at ftp://ftp.stsci.edu/cdbs/acs_aux Please remember that the sensitivity files are FITS TABLES and need to be opened with appropriate software.