RGS spectrum of HR1099
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Does BACKSCAL take into account all the "blank areas" in a spectrum extraction region?

EPIC X-ray spectra are expressed in counts per spectral channel. Spectral fitting programs such as XSPEC apply the proper renormalization to the background spectra, using the value of the BACKSCAL keyword in the header of the spectral file(s). The SAS task backscale calculates the BACKSCAL value. backscale is automatically run, when a spectrum is extracted via xmmselect.

Users must be aware that the current implementation of backscale employs the full area of the spectrum extraction region, save the (known) bad pixels/columns. Other effects, such as:

are also taken into account.


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Updated on: November 18, 2006