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The mean pulse height analyzer channel (PHA) of a spectral distribution will vary depending on its location on the detector. Below is a method to compare observed data with that of preflight calibration measurements. Note however that this will give only approximate values since the actual data obtained with the wobble correspond to a finite band on the detector rather than a specific location.
For temporal gain variations, see The HRI Calbration Report .
cl> imhead rh*.qp | match ROLL_NOM
NOTE: The roll angle for US processed REV 0 data is given with different signs in the header compared to that of the printout (which is correct). Therefore the above method should be used only for RDF data.
> ftp sao-ftp.harvard.edu > cd /pub/rosat/calfiles > get README > binary > get gain_al.fits > get gain_c.fits > get gain_cu.fits > quit
> rotate
NOTE: use the following parameters
rotation angle= | (switch the sign of ROLL_NOM) |
xin=258 | |
yin=254 | |
xout=INDEF | |
yout=INDEF | |
ncols=512 | |
nlines=512 | |
interpo=poly3 | |
boundary=constant | |
constant=0.0 |
> display rh*_im1.imh
NOTE: The wobble means that a general area of the detector/gain map will contribute to any give source.
where
is the summation from i=1 to i=15
N(i) is the number of counts in channel i.