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: http://xmm.vilspa.esa.es/sas/7.0.0/documentation/threads/omf_stepbystep.html
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The data package received by the investigator contains OM data which
normally do not necessitate further processing for the purpose of
calibration.
However, a
user may want to apply the most recent calibrations, or to change some
default parameters to e.g. improve the source detection on his/her
data.
It may not be necessary to run the complete chains, but just some
tasks. All this
can be done interactively.
The SAS_ODF environment variable shall be set to the summary file produced by odfingest, or to a directory containing the data, and access to calibration files shall be set through cifbuild.
In addition to the fits files containing the science data, the ODF needs to contain the OM house-keeping files:
0644_0125321001_OMX00000NPH.FIT - non periodic house-keeping
0644_0125321001_OMX00000PEH.FIT - periodic house-keeping
and spacecraft files of the following form:
0644_0125321001_SCX00000SUM.SAS - ASCII observation summary file
0644_0125321001_SCX00000TCS.FIT - Spacecraft Time correlation file
0644_0125321001_SCX00000ATS.FIT - Spacecraft Attitude file
Invoking omichain or omfchain will
automatically
start the processing of all OM data in the working directory. The
duration
of the process will depend on the number of exposures and windows and
at
the end we shall obtain the final processed files. No intermediate file
will be preserved.
In the standard automatic SSC pipeline processing, the temporary image files are re-used and thus overwritten. In the task by task processing, they can be distinguished so that intermediate stage output can be looked at if desired. In the next examples we have used the same naming system than omfchain. This allows us to maintain some intermediate files which can be helpful in understanding the whole process.
Some of the default parameters used by individual tasks can be tuned
if necessary.
the following files are necessary (they are normally part of the ODF):
0644_0125321001_OMS00200WDX.FIT - Exposure priority window file
0644_0125321001_OMS00200THX.FIT - Exposure tracking history file
0644_0125321001_OMS00202FAE.FIT - Exposure fast mode data file (fast mode window)
and the process can be run task by task in the following way. Note
that output products of the different tasks have been given the names
that
omfchain would have applied.
It is assumed throughout this example that the ODF data are in:
/path_to_your_data/
and we are running the tasks and writing their results in a
subdirectory:
/path_to_your_data/fast/
step 1 The OM tracking data are processed for later use, if applicable.
omprep set=/path_to_your_data/0644_0125321001_OMS00200THX.FIT pehset=/path_to_your_data/0644_0125321001_OMX00000PEH.FIT nphset=/path_to_your_data/0644_0125321001_OMX00000NPH.FIT wdxset=/path_to_your_data/0644_0125321001_OMS00200WDX.FIT outset=/path_to_your_data/fast/tmp_tracking modeset=3
As for image data, if there is no THX file, then set=DUMMYTHX.FIT.
omprep
will generate a dummy file needed for the rest of the chain, with zero
drift in it.
step 2 A plot of the tracking data, useful to assess the S/C stability during the exposure, is generated. Note that tracking data may not be good enough, in which case no plot is produced.
omdrifthist set=/path_to_your_data/fast/tmp_tracking
plotfile=/path_to_your_data/fast/P0125321001OMS002TSHPLT0000.PS
trackradius=0.5
hardcopy=yes
step 3 The count rates of tracking stars are written into a file.
omthconv thxset=/path_to_your_data/fast/tmp_tracking
nphset=/path_to_your_data/0644_0125321001_OMX00000NPH.FIT
outset=/path_to_your_data/fast/P0125321001OMX002TSTRTS0000.FIT
modeset=1
step 4 Processing of the fast mode data starts here.
omprep set=/path_to_your_data/0644_0125321001_OMS00202FAE.FIT pehset=/path_to_your_data/0644_0125321001_OMX00000PEH.FIT nphset=/path_to_your_data/0644_0125321001_OMX00000NPH.FIT wdxset=/path_to_your_data/0644_0125321001_OMS00200WDX.FIT outset=/path_to_your_data/fast/F0125321001OMS002EVLIST2000.FIT modeset=1
In its second run, omprep is invoked for fast data ( modeset=1)
and the FAE raw event data is transformed into a modified event list to
be used as input for evselect
step 5 Starting the processing of the detected events.
evselect table=/path_to_your_data/fast/F0125321001OMS002EVLIST2000.FIT withimageset=yes imageset=/path_to_your_data/fast/F644_0125321001_OMS00202FIMI.FIT xcolumn=RAWX ycolumn=RAWY
The pseudo-image corresponding to the fast mode OSW has been created
by this first run of evselect.
step 6 Correcting for drift.
omfastshiftnphset=/path_to_your_data/0644_0125321001_OMX00000NPH.FIT set=/path_to_your_data/fast/F0125321001OMS002EVLIST2000.FIT thxset=/path_to_your_data/fast/tmp_tracking interpolate=yes
The X- and Y- coordinates of the photon events are corrected for
spacecraft
drift. New columns are added to the event list with the corrected
values.
Although no real flat field correction exists for OM, nor is it necessary, the processing requires such a file which can be generated using the task omflatgen as follows. (This task can also be run at the beginning of the processing)
step 7.0
omflatgen outset=0644_0125321001_OMX00000FFX.FIT
The output flatfield (primary extension) will be set to unity.
step 7
omfastflatset=/path_to_your_data/fast/F0125321001OMS002EVLIST2000.FIT slewflatset=/path_to_your_data/0644_0125321001_OMX00000FFX.FIT fastimgset=/path_to_your_data/fast/P0125321001OMS002IMAGE_2000.FIT oswflatset=/path_to_your_data/fast/F0125321001OMS002FLAFLD2000.FIT
Here again, the system is prepared to apply a subset of the omflatgen
generated flat field to the fast mode window data, taking into account
the spacecraft drift. The flat field is set to one, and therefore this
correction has no real effect. The task generates the tracking shifted
F0125321001OMS002FLAFLD2000.FIT (only for
the fast mode window) and the corrected pseudo image image.fit.
step 8
omdetect nsigma=6 set=/path_to_your_data/fast/P0125321001OMS002IMAGE_2000.FIT regionfile=/path_to_your_data/fast/F0125321001OMS002REGION2000.ASC outset=/path_to_your_data/fast/P0125321001OMS002SWSRLI2000.FIT
The output region will allow the user to check the proper detection
of the source in the small fast window. The PSF information is used to
parameterize the detected source.
step 9
omatt set=/path_to_your_data/fast/P0125321001OMS002IMAGE_2000.FIT sourcelistset=/path_to_your_data/fast/P0125321001OMS002SWSRLI2000.FIT ppsoswset=/path_to_your_data/fast/P0125321001OMS002SIMAGE2000.FIT usecat=no rotateimage=yes tolerance=3
Astrometry is applied as for image data. The pseudo-image is north
aligned
too.
step 10
omregion set=/path_to_your_data/fast/P0125321001OMS002SWSRLI2000.FIT srcnumber=1 srcradius=-6 nfwhm=3 bkginner=1.2 bkgouter=2.5 bkgfile=/path_to_your_data/fast/F0125321001OMS002BGDREG2000.FIT srcfile=/path_to_your_data/fast/F0125321001OMS002SRCREG2000.FIT
These regions will be used by evselect to filter out
the
event list, extracting the corresponding photon events for the source
and
the background. Optional parameters can be used to fine-tune the
definition
of the regions.
step 11 Source events
evselect table=/path_to_your_data/fast/F0125321001OMS002EVLIST2000.FIT
expression='((WIN_FLAG
.eq. 0) .and.
(region(/path_to_your_data/fast/F0125321001OMS002SRCREG2000.FIT,
CORR_X, CORR_Y)))' xcolumn=CORR_X
ycolumn=CORR_Y
rateset=/path_to_your_data/fast/F0125321001OMS002SCRATE2000.FIT
timecolumn=TIME
timebinsize=10
maketimecolumn=yes
withrateset=yes
step 12 Background events
evselect table=/path_to_your_data/fast/F0125321001OMS002EVLIST2000.FIT
expression='((WIN_FLAG
.eq. 0) .and.
(region(/path_to_your_data/fast/F0125321001OMS002BGDREG2000.FIT,
CORR_X, CORR_Y)))' xcolumn=CORR_X
ycolumn=CORR_Y
rateset=/path_to_your_data/fast/F0125321001OMS002BGRATE2000.FIT
timecolumn=TIME
timebinsize=10
maketimecolumn=yes
withrateset=yes
And finally the light curve can be obtained and plotted. The
photometric
corrections are also applied (coincidence loss, dead time, PSF,
magnitude
conversion)
step 13
omlcbuildsrcregionset=/path_to_your_data/fast/F0125321001OMS002SRCREG2000.FIT bkgregionset=/path_to_your_data/fast/F0125321001OMS002BGDREG2000.FIT srcrateset=/path_to_your_data/fast/F0125321001OMS002SCRATE2000.FIT bkgrateset=/path_to_your_data/fast/F0125321001OMS002BGRATE2000.FIT sourcelistset=/path_to_your_data/fast/P0125321001OMS002SWSRLI2000.FIT wdxset=/path_to_your_data/0644_0125321001_OMS00200WDX.FIT outset=/path_to_your_data/fast/P0125321001OMS002TIMESR2000.FIT
step 14
lcplot set=/path_to_your_data/fast/P0125321001OMS002TIMESR2000.FIT
binsize=1
plotdevice=/PS
plotfile=/path_to_your_data/fast/F0125321001OMS002TIMESR2000.PS
bkgdyscale=no