# EDM Tue Apr 19 13:37:27 EDT 2011

The NXB (non X-ray background) events lists are:

nxb_xis0_sciof_20071226_cl_filt.evt.gz
nxb_xis0_scion_20101201_cl_filt.evt.gz
nxb_xis1_sciof_20080917_cl_filt.evt.gz
nxb_xis1_scion_20101201_cl_filt.evt.gz
nxb_xis2_sciof_20071226_cl_filt.evt.gz
nxb_xis2_scion_20071226_cl_filt.evt.gz
nxb_xis3_sciof_20071226_cl_filt.evt.gz
nxb_xis3_scion_20101201_cl_filt.evt.gz

There is one event list for each XIS0,1,2,3 with space-row charge injection
(SCI) on and off.  These event lists are from the CALDB version indicated
in the filename, current as of today, and they have been reprocessed with
the XIS pipeline ftools and filtered to include only PI=100:2500 or
energy=365:9125 eV to make them smaller.  So don't use them for energies
outside of that range.  

I would suggest using a local version of the CALDB rather than the
online version.  This will speed things up in general.

Below is a sample "xisnxbgen" command, to use these local event lists
just set "nxbevent" to the proper filename.  The "sortstep" and "sortkey"
should match whatever filtering were used in xselect to make the spectra;
if no COR or COR2 filtering were done, then
"sortstep=0,1,2,3,4,5,6,7,8,9,10,11,12,13,99" is the right one to use.  I
would recommend filtering on COR2=6:99 as I have done here, unless it
removes a substantial amount (>20%) of the exposure time, as it reduces the
background quite a bit.

Make sure to set "apply_xisftools=no" if using these local event lists, so
that it doesn't waste time reprocessing them.

If you use "region_mode=SKYREG", you will need to supply the attitude file.
This procedure might give a warning, but in general it should do a good
job.

Using "pixq_and=65536" will remove the calibration source regions, while
"pixq_and=0" will leave them in.  Probably doesn't matter for a 3-6 arcmin
annulus if the cluster is at the center.

time xisnxbgen \
     outfile=${nxbphafile} \
     phafile=${phafile} \
     region_mode=DETREG \
     regfile=${regfile} \
     orbit=${orbfile} \
     attitude=none \
     ehkfile=${ehkfile} \
     gtifile=none \
     nxbevent=${nxbevtfile} \
     nxborbit=CALDB \
     nxbvdchk=CALDB \
     nxbcorhk=CALDB \
     sortkey=COR2 \
     sortstep="6,7,8,9,10,11,12,13,99" \
     pi_min="${pi_min}" \
     pi_max="${pi_max}" \
     time_min="-150" \
     time_max="+150" \
     apply_xisftools=no \
     pixq_min=0 \
     pixq_max=524287 \
     pixq_and=0 \
     pixq_eql=0 \
     chatter=0 \
     clobber=yes \
     mode=hl 

#pset xisnxbgen pixq_and=65536