Bin the aspect solution into a 3D histogram of duration vs
pointing offset and roll offset.
asphist infile outfile evtfile dtffile [geompar] [res_xy] [res_roll]
[max_bin] [clobber] [verbose]
The aspect solution is given every 0.256 seconds during an
observation. The aspect solution can be put into a very compressed
form by making a histogram of the pointing vs. x-offset, y-offset, and
roll-offset. The value in each bin is the time the pointing was
within that offset bin during the observation, as modified by the
good-time interval (GTI) and dead-time-correction factor (DTF).
(The information which is lost is the absolute time at which the
pointing was at each offset.)
The histogram is primarily used to shorten the time required
to compute the response averaged over the observation (see
mkarf, mkgarf, mkexpmap). Another use for the histogram is
to provide all the observational configuration (detector,
date) via the file's header.
The input file is the aspect solution, which contains the
optical axis' right ascension, declination, and roll
vs. time. These are combined and converted to pixel offsets,
and the duration integrated for
each offset. The actual position of the optical axis on the
detector is lost in this process, but the result is not used
for explicit event coordinate transformations where this
information would be crucial. Instead, we have information
which allows us to map the detector outline to the sky.
asphist pcad_asol.fits asphist_7.fits
evtfile="acis_evt2.fits[ccd_id=7]" dtffile=""
This shows the preferred way of specifying the
good-time filter by specifying the chip. (Due to
telemetry saturation, each chip may have a different
exposure.) Note that this is a change in syntax from
CIAO 3.2; the OLD syntax was:
asphist "pcad_asol.fits[@acis_evt2.fits[ccd_id=7]]" asphist_7.fits
acis_evt2.fits dtffile=""
asphist infile=@hrc_stk.lis outfile=mytest_hist.fits
evtfile=hrc_evt1.lis dtffile=@stack_dtf1.lis
Use a list of aspect solution files, an event file,
and HRC dead-time-factor files.
asphist infile="asol.fits" outfile=asphist.fits
evtfile="evt1.fits[ccd_id=0]" dtffile=""
Use a single aspect solution file with the specified
GTI table.
Parameter=infile (file required filetype=input stacks=yes)
Input aspect solution file(s). A single file or a
stack. Currently, the aspect solution input files must
be time-sorted.
For one or multiple input file(s), there should be only
one single ASPHIST table in the outfile.
( see the parameter 'outfile' )
Name of the file to write, holding a table of the aspect histogram
(extension 'ASPHIST'), and a table of the good time intervals
(extension 'GTI').
The GTI table contains the columns of START and STOP,
and the ASPHIST table contains the columns,
-
CAH_REC - bin, Int4, histogram bin
-
X_OFFSET - pix, Real8, Offset in sky x pixels
-
Y_OFFSET - pix, Real8, Offset in sky y pixels
-
ROLL_OFFSET - deg, Real8, Offsets in roll
-
DURATION - s, Real8, Bin Duration (corrected for LT and GTI)
The total of all durations is the EXPOSURE, which is corrected for
the live-time and good-time. Since each detector element can have a
unique GTI or DTF, each chip will have unique aspect histogram and
EXPOSURE keyword.
Parameter=evtfile (file required filetype=input stacks=yes)
Input event file name(s). If a stack, only uses the first element.
This file provides information of nominal pointing positions and
the SIM factors. It should contain the keywords :
NOM ,
SIM ,
DETNAM ,
DTCOR (for ACIS).
The evtfile should have a filter appended to it, the preferred
syntax being "[ccd_id=x]" for the ACIS case.
None is needed for HRC (since there is only one valid GTI for all
HRC chips).
This filter is used for two reasons. First, the aspect
solution needs to be time filtered the same as
the event file. The simplest way to do so is use the event
file's GTI tables directly. Second, without the ccd_id=x, we pick the
first subspace (which for ACIS is by default the aim chip).
This may or may not be what you're looking for -- the "ccd_id=x"
selects the correct GTI for your analysis..
If you knew the GTI ranges, you could just as easily do
"evtfile=evt.fits[time=a:b,c:d,...]"
and not filter with the event/GTI filters at all.
Input DTF file name(s). A single file or a stack.
The dead-time-correction-factor file (and extension). This is an
efficiency factor which weights the exposure durations as they are
summed into each offsets bin.
For HRC, the files for the dead-time-correction-factors are the
"hrcroot_dtf1.fits" files. For ACIS, the livetime
correction is from the keyvalue of DTCOR in the
principle extension (EVENTS).
The name of the Pixlib Geometry parameter file.
Resolution desired, in arcseconds, for both the X and Y offsets.
The default is 0.5 arcseconds, which is about 1 ACIS pixel.
The resolution in roll (or size of a roll bin) in arcseconds. The
default is 600 arcseconds. This is not as big as it seems. 600
arcseconds roll about the center of HRC-I causes a linear translation
at the edge of the array of about 4 arcsec, which is smaller than the
local PSF, and smaller than the resolution of the QE calibration.
Clobber output if it exists?[y/n]
The tool usage has been modified to associate the good time
interval (GTI) filter with the event file rather than the
aspect solution; see Example 1.
In prior versions of CIAO, a large number of GTI records
(as often occurs for ACIS in CC-mode) would cause
slight underestimates of the duration, since the filtering does
not interpolate times in aspect records, but drops whole records.
Applying the filter from the events and reading all the aspect
records results in a rigorous interpolation of time intervals and
determination of exposure time.
The kernel parameter has been removed.
The tool has been rolled back to an earlier version. This was done
to resolve a number of problems with multi-OBI and multi-ObsID
datasets.
The delta_xy and delta_roll parameters
introduced in CIAO 3.2 were not available in this version of
asphist, therefore they have been removed from the parameter
file.
- calibration
-
ardlib
- tools
-
acis_bkgrnd_lookup,
acis_fef_lookup,
acis_set_ardlib,
acisspec,
add_grating_orders,
add_grating_spectra,
dither_region,
dmarfadd,
dmfilth,
dmregrid,
fullgarf,
mkacisrmf,
mkarf,
mkexpmap,
mkgarf,
mkgrmf,
mkinstmap,
mkpsf,
mkrmf,
mkwarf,
psextract,
psf_project_ray,
rmfimg,
specextract
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