HXD/PIN Background Files
-
PIN background for observations up to 2006 May 23
- However, check this location for "bgd_d" files for observations obtained between 2006 Mar 23 and May 13.
- PIN background for observations between 2006 May 24 and Oct 2 (for 48 out of 64 diodes, or "W123" - see explanation)
- PIN background for observations after 2006 Oct 3 (for 32 out of 64 diodes, or "W23" - see explanation)
In all the areas above, the files for a given observation can be found using the sequence number.
See the explanation of background files for details.
Usage:
- The background event files have a GTI extension (extension #2).
The background estimation is performed only within the GTIs listed.
For further filtering, you should make a new GTI by ANDing the GTI from
your filtering criteria with the GTI extension of the background files.
- It is necessary to correct for the dead time of the observed
spectrum to apply the background file correctly. The dead time
correction tool (hxddtcor) is included in the latest release
of the Suzaku ftools.
On the other hand, dead time correction is not necessary for the PIN background files, except for bgd_d files.
- The event rate in the background event file is 10 times higher than
the real background to suppress the Poisson errors. Therefore,
users should increase the exposure time of derived background spectra
and light curves by a factor of 10 using, e.g., fmodhead.
- The background event file does not include the cosmic X-ray background
(CXB). Since the CXB flux is about 5% of the background for PIN, you
should take it into account after subtracting the background.
We will provide the simulated CXB spectrum for the HXD/PIN, but
keep in mind that it is yet to be confirmed with actual observations.
See note on PIN CXB described below.
- The accuracy of the background model is expected to reach as good as
5-10 % of the average background. However, since May 24, 2006, one
of four high voltages has been reduced to 400 V from the nominal bias
of 500 V, due to in-orbit degradation, and this effect on the detector
background has not yet been taken into account. Guest observers are
strongly recommended to verify the reliability of the background model,
by comparing the model spectrum with the "earth occultation
spectrum," which can be obtained by screening with "ELV<-5."
- The background modeling is still under development, and the evaluation of the systematic errors of these background event files has not been completed yet. Users should compare light curves of the observation and the background model. We also encourage users to compare the earth occultation data of your observation with the background event files, to examine the accuracy of background model for your observation.
Please note that these background files contain the estimates for the NXB only, and that cosmic X-ray background (CXB) level must be estimated separately.
- A recipe for estimating the CXB level in HXD/PIN data
If you have any questions concerning Suzaku, visit the Feedback form.