Find the FITS Embedded Function file for use by mkrmf
acis_fef_lookup infile chipid chipx chipy [outfile] [verbose]
This tool returns the location of the FITS Embedded Function (FEF) file
needed by mkrmf to make either a PI or a PHA RMF for a point source
observed by ACIS.
It is not needed if you are creating a weighted response (ie
for an extended source) using
mkwarf and mkrmf, since the CALDB can be automatically queried
in this case, although acis_fef_lookup can be used if desired.
When run, the tool prints the location of the FEF file (including any
necessary spatial filter) to the screen and to its outfile parameter.
This makes it easy to use from the shell, or script, since pget can be used to
access the file name:
unix% set feffile = `pget acis_fef_lookup outfile`
or the parameter redirection syntax (see
"ahelp parameter") can be used:
unix% pset mkrmf infile=")acis_fef_lookup.outfile"
The script can be used in two modes:
- Point source
- Extended source
You must supply the location of the source in CHIP coordinates - ie
the value of the ccd_id, chipx, and chipy columns from the event file.
The returned file name includes a DM spatial filter which specifies the
part of the FEF file to use.
Since the dither pattern of Chandra means that even a point source
moves over a non-negligible number of pixels, and likely over multiple
FEF tiles, the decision of
what location to use is not a simple one, and depends on your science goals
and the location of the source (eg is it near a chip gap or does it
fall on more than one node).
If you wish to use mkrmf with a weight map, created by mkwarf, then you
need the location of the FEF file without the spatial filter used in the
point source case. This is achieved by setting chipid to "none" (the
values of the chipx and chipy parameters are ignored in this case).
However, this step is not needed since mkwarf and mkrmf
can accept a CALDB query (e.g. feffile=CALDB)
for the FEF file when using weights files.
The
CIAO thread pages
discuss in greater detail the steps necessary to calculate the ARF and
RMF for a source.
unix% acis_fef_lookup evt2.fits 5 512 512
.../acisD2000-01-29fef_pha_ctiN0004.fits[FUNCTION][ccd_id=5,chipx=449:51
2,chipy=449:512]
(the full path has been excluded for brevity)
This gives the file name of the FEF file applicable for
the observation and position on the detector.
In this example the input events file is for an obervation at a focal plane
temperature of -120 degrees C and which has had the CTI correction
algorithm (see acis_process_events) applied to it.
One can then run mkrmf by either explicitly setting its infile parameter
to the output of this tool, for instance by using pget
(using tcsh shell syntax and again ignoring the full path) -
unix% set feffile = `pget acis_fef_lookup outfile`
unix% echo $feffile
.../acisD2000-01-29fef_pha_ctiN0004.fits[FUNCTION][ccd_id=5,chipx=449:512,chipy=449:512]
- or by using the
redirection capabilities of the parameter interface -
unix% mkrmf infile=")acis_fef_lookup.outfile" ...other parameters..
See "ahelp parameter" for more on the parameter
interface.
unix% acis_fef_lookup evt2.fits none
.../acisD2000-01-29fef_pha_ctiN0004.fits[FUNCTION]
(the full path has been excluded for brevity)
Find the name of the FEF file but without any spatial filter.
This is useful when creating weighted responses for
extended sources.
unix% acis_fef_lookup spectrum_cti.pi none
.../acisD2000-01-29fef_pha_ctiN0004.fits[FUNCTION]
(the full path has been excluded for brevity)
Here we repeat the previous example but using a spectrum
(PHA format; the column that was binned on - ie PHA or PI - is unimportant)
which was extracted using dmextract from an events file that had
been CTI corrected.
Parameter=infile (string required filetype=input)
Source file (event or spectrum)
The infile parameter can accept any file that contains enough
information in its header for the quizcaldb tool to work;
event files (L1 and L2) and PHA-format files produced by dmextract are
both suitable.
The necessary keywords that infile must contain are:
TELESCOP, INSTRUME, DATE-OBS, and DATE-END.
The following keys are also used if found:
DETNAM, FILTER, CTI_APP, and CTI_CORR.
ACIS chip number
This parameter is used to define which ACIS chip you want the
FEF for. The allowed parameters are 0-9 (for the 10 chips ACIS-0
to ACIS-9) or the string "none". This last option makes the tool
ignore the values of the chipx and chipy parameters and
just report the FEF file (with block name).
Parameter=chipx (integer required default=1 min=1 max=1024)
ACIS chip x coordinate
The spectral response of the ACIS chips depend on location
within the chip (ie in which FEF tile the source falls). The chipid,
chipx and chipy parameters specify this position, where chipx/y
are in chip coordinates (ie 1 to 1024).
If chipid=none then this value is neither prompted for nor used.
Parameter=chipy (string required default=1 min=1 max=1024)
ACIS chip y coordinate
The spectral response of the ACIS chips depend on location
within the chip (ie in which FEF tile the source falls). The chipid,
chipx and chipy parameters specify this position, where chipx/y
are in chip coordinates (ie 1 to 1024).
If chipid=none then this value is neither prompted for nor used.
Parameter=outfile (string not required filetype=output)
FEF file to use
This parameter is filled by the tool when it has run, and
contains the name of the FEF file to use, including any
spatial filter (if chipid was not set to none).
The value can be accessed using pget/plist/pdump; for instance:
unix% set feffile = `pget acis_fef_lookup outfile`
unix% echo $feffile
.../acisD2000-01-29fef_pha_ctiN0004.fits[FUNCTION][ccd_id=5,chipx=449:512,chipy=449:512]
Parameter=verbose (integer not required default=0 min=0 max=5)
Verbose level
If set to a non-zero value then the tool will output extra
information (other than the name of the FEF file) when
run. This information is only likely to be useful when
debugging the tool.
When looking up certain chipid values with CTI-corrected data,
the script prints a warning that users should use mkacisrmf to
create the RMF response, not acis_fef_lookup and mkrmf. The
warnings are printed at verbosity > 0. The Creating ACIS RMFs with mkacisrmf thread has information on using
that tool.
The tool has been updated to support the CTI_APP keyword
and will no longer exit if the CTI_CORR keyword is stored
as an integer, rather than a boolean, in the file header.
If the chipid is set to "none" then the chipx and chipy
parameters will not be asked for.
The tool will now exit with an error if the CTI_CORR keyword
exists in the header of the input file but it is not a boolean.
There are separate FEF files for each focal plane temperature
since the spectral response varies with chip temperature.
Prior to the CIAO 2.3 release (November 2002), there were
separate FEF files for PI and PHA RMFs; with the
introduction of the "dynamic rebinning" (aka "PI on the fly")
mode of mkrmf there are now only PHA FEF files.
As the CTI correction algorithm recovers much of the resolution
lost due due to the radiation damage there are also separate
FEF files for use with data that has and has not been CTI corrected.
Each ACIS chip is split up into a number of tiles and the response is
assumed to be constant within each tile. The size of these
tiles depends on the type of chip (whether it is front or
back illuminated) and the focal-plane tempertature.
Currently, as of the CIAO 3.0 release in summer of 2003, the
minimum size for a tile is 32 by 32 pixels and the largest
size is 256 by 32 pixels (note that no tile crosses a node
boundary).
- calibration
-
ardlib
- tools
-
acis_bkgrnd_lookup,
acis_set_ardlib,
acisspec,
add_grating_orders,
add_grating_spectra,
asphist,
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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