Response matrices

SIS spectral response

Each SIS camera comprises 4 CCD chips, each of which requires its 
own RMF. This leads to the naive expectation that 8 RMFs should be 
all that are required. Regrettably this is not the case. A different RMF 
is also required for different event grades, split thresholds, or echo 
correction. The calibration database contains a selection of RMFs to 
cover the common choices. The names of these files are constructed 
out of the following, with one choice per row:

 s0 s1                   SIS0 or SIS1
 c0 c1 c2 c3 c4          Chip0, Chip1, Chip2, or Chip3
 g0 g02 g0234            Grade combinations
 p20 p40                 Split threshold 20 or 40
 e0 e1                   Echo (un)corrected (1)0
 512 1024                Number of channels

All AO observations have been performed with a split threshold of 
40. Unless you are analyzing Faint mode data and specified that echo 
correction was to be performed then you should use the e1 option. In 
fact, since most observations have been observed with the default 
grade combination of g0234, we have created the following RMF files 
with this grade and with the default pointing positions:

 sis0:

 s0c1g0234p40e1_512_1a.rsp   - 1-ccd mode
 s0c1g0234p40e1_512_2a.rsp   - 2-ccd mode
 s0c1g0234p40e1_512_4c.rsp   - 4-ccd mode

 sis1:

 s1c3g0234p40e1_512_1a.rsp   - 1-ccd mode
 s1c3g0234p40e1_512_2a.rsp   - 2-ccd mode
 s1c3g0234p40e1_512_4c.rsp   - 4-ccd mode 

and placed them in the directory:

 /caldb/data/asca/sis/cpf/93dec20

accessible via anonymous FTP at legacy.gsfc.nasa.gov.

If the available RMFs do not slake your thirst for variations you can 
create your own matrices using the SISRMG FTOOL.

The calibration database also contains RSP files containing the ARFs 
appropriate for point sources at the nominal pointing positions. These 
are identified as the RMFs but with the addition to the names of:

 1c        center of the chip
 1a        nominal 1-CCD pointing position (AO)
 1p        nominal 1-CCD pointing position (PV)
 2a        nominal 2-CCD pointing position (AO)
 2p        nominal 2-CCD pointing position (PV)
 4c        nominal 4-CCD pointing position 

ARFs can be calculated for extended sources using the NPSARF 
program which weights the telescope effective area by the number 
of photons at each position in the selected region.