Selection using the XTE Filter File
In XSELECT nomenclature, the XTE Filter File is an 'MKF' file (because
this is what ASCA calls it). The code will, however, correctly
identify a file with a .xfl suffix as a filter file. You'll have to
make the filter file outside of XSELECT, but you can use this file
within the program. (Note that XSELECT will default to looking for
filter file information in the DATADIR directory tree - which is, of
course, often the right answer - unless you explicitly set the MKFDIR
to point at your working directory, as in the example below.)
To plot values in an existing XTE Filter File, use 'mkfbin', then
'plot mkf'. To select good time based on the values in the Filter
File, use 'select mkf' followed by 'extract', as follows:
set mkfdir /data/kaah5/xtegof/alan/X1323_New
mkfbin "NUM_PCU_ON ELV BKGD_THETA"
> 16.0
plot mkf
select mkf "ELV .gt. 5.0 .AND. NUM_PCU_ON .gt. 3"
extract curve
Background subtraction
Create your background datafiles outside of XSELECT, using
(RUN)PCABACKEST
in your current working directory. You'll end up
with an ASCII list of background files, e.g. bg_00.files. Your goal is to
swap back and forth between analyzing source data and background data,
so you can use the same selection criteria for both, but this requires
some sleight of hand since the data live in different places.
Let's assume you've been doing some work on the source data as
described above. You now want to switch to your background files, and
you'll need to change directories to your working directory in order
to see them, if you haven't done so already:
set datadir
> /data/kaah5/xtegof/alan/X1323_New/Xsel.test
(or appropriate directory name). At this point a 'make obscat' will
automatically find all the background files (and everything else in
this directory and directories beneath that looks like an XTE data
file!), or you can use the filename created by RUNPCABACKEST, as
follows:
read events "bg_00.files"
choose "1-2,12-15,17-18"
You will (may) be asked if you wish to 'clear filters?', and your
answer will probably be "No" if you want to keep your previous
filtering in place for the background.
Then proceed with data extraction and examination as above. When
you're ready to go back to the source datafiles, return by simply
reading back in the .xdf file, or re-setting the datadir and remaking
the obscat, as described earlier.
NOTE that the obscat of the background
files will look very similar to the obscat of the source-data
files, because the keyword values it reads are largely identical
in both. The difference is in the HDUCLAS2 column, which reads
'TOTAL' for source data, and 'BACKGROUND' for background data.
Other bells and whistles
XSELECT is a mature program that has been in use for many years to
analyze data from e.g. ASCA and ROSAT. If you want to do something
straightforward like clear or manipulate a filter, display data in a
different way etc, odds are that XSELECT probably already does
it. Look in the online help or the manual for more details. For
example, to clear filters, use commands such as
clear detector
clear time
You can also write simple scripts to run XSELECT in batch, once
you gain some experience with the program.
After using XSELECT
Once you've used XSELECT to create source and background spectra,
source and background light curves, etc, you will probably want to do
further analysis. Before undertaking spectral analysis, you'll
need to create a response
matrix for your spectrum using the PCARSP tool.
If you're new to X-ray data analysis, you'll want to study
the online information about the XSPEC and
XRONOS packages, for spectral and timing analysis respectively.
For further information about RXTE data and the FTOOLS suite available
for their analysis, please see
the extensive userguides on our
data analysis pages,
including our
Getting Started Guide,
the complete guide to RXTE data in
The ABC of XTE,
and especially the recipes in the
RXTE Cook Book.
If you have a question about RXTE, please send email to one of our
help desks.
