The name of the file containing the binned aspect history in the form of an aspect histogram.

Note that each ACIS CCD has its own GTI file. This means that each chip will have its own aspect histogram file.

The name of the output ARF file.

These parameters specify the (x,y) sky position [pixels] of the point source, in the appropriate tangent plane coordinate system for the detector.

Energy grid specification string. This string may specify either a file or an explicit energy grid. For example, to read a grid from the block MATRIX of an RMF file called rmf.fits, use:

"engrid=grid(rmf.fits[MATRIX][cols ENERG_LO,ENERG_HI])"

To specify an explicit grid running from 0.3 keV to 10.0 keV in 0.01 keV increment steps, use:

"engrid=0.3:10.0:0.01"

The name of a FITS file, such as a level 2 event file, containing keywords which specify the mission, detector, SIM offsets, start time, etc.

The value of this parameter is passed to ARDLIB to select a particular detector subsystem so that the appropriate QE can be computed. It specifies the specific device (e.g. the specific chip or MCP of the detector) for which the ARF is to be computed. For Chandra, it must specify one of the following detector subsystems:

HRC-I
HRC-S1, HRC-S2, HRC-S3
ACIS-I0, ACIS-I1, ACIS-I2, ACIS-I3
ACIS-S0, ACIS-S1, ACIS-S2, ACIS-S3, ACIS-S4, ACIS-S5
ACIS-0, ACIS-1, ACIS-2, ACIS-3,
ACIS-4, ACIS-5, ACIS-6, ACIS-7, ACIS-8, ACIS-9

For these detector subsystems, the following qualifiers or options are supported:

QE=value
CONTAM=yes|no
UNIFORM (forces QE to be uniform)
IDEAL (equivalent to "QE=1;UNIFORM;CONTAM=NO")
CHIP=value (CHIP=4 ==> ACIS-4 (ACIS-S0))
WINDOW=xmin,ymin,xmax,ymax
REGION=BOX(xcenter,ycenter,xsize,ysize)
REGION=RECTANGLE(xmin,xmax,ymin,ymax)
TIME=value (in seconds since MJDREF)

Note that only simple rectangular regions are supported.

For ACIS, the BPMASK qualifier allows one to include bad pixels selected according to the status column in the bad pixel file:

BPMASK=hex value (Specified as, e.g., 0x39ff)
BPMASK=dec value (Specified as, e.g., 14847)
BPMASK=FAINT (=0x39ff, 14847)
BPMASK=VFAINT (=0x3fff, 16383)

If this option is not present, the default is FAINT.

This parameter controls whether or not to compute a zeroth order grating ARF. For grating observations, the value is either HETG or LETG. For imaging observations, the value of this parameter is NONE.

Note: For HETG, the PSF in zeroth order is believed to be identical to the imaging PSF. However, for LETG this is definitely not the case and it is unclear whether or not the PSF library will properly handle this case. For this reason, it is recommended that the region be selected to guarantee a PSF fraction of 1.0.

The mask file (msk1.fits) for the observation. The mask file is needed in particular when a window or subarray was used. A value of "NONE" indicates that no mask file will be applied.

The parameter block file, which defines ACIS pixel clocking parameters, is a standard product of pipeline processing and is available for every observation. This file contains information which defines how long any pixel is exposed before being read-out, which is related to the probability that any pixel will be disabled ("deadened") by cosmic rays. See the description of the "dafile" parameter for more information on ACIS dead area.

Parameter block files have names of the form, "acisf146860615N001_pbk0.fits". The long string of digits refers to the time of observation (seconds since reference date) and "N001" is a revision number.

Since the pbkfile contents are observation-dependent, there is no default other than "NONE". In this case, no dead area correction is applied, and dafile is assumed to have the value "NONE". If pbkfile is set to a valid file, then the dafile parameter must also refer to a calibration file.

The pbkfile parameter is ignored for HRC data.

ACIS "dead area" coefficients file, which may have the values "NONE" (no dead area computation), CALDB (for automatic lookup), or an explicit file reference to an ACIS "dead area" coefficients FITS table.

The ACIS dead area refers to a slight decrease in detector efficiency due to the background cosmic ray flux which temporarily renders some pixels useless. The calibration product is a coefficient (per CCD) which gives the fractional area lost (or "deadened") per second. Since the area lost increases with time, the magnitude of the effect depends upon the ACIS clocking parameters (number of rows, window location, frame-time) which determine how long a pixel was exposed to the background cosmic ray flux during the primary exposure and during electronic readout from the frame-store area. For full-frame timed-exposure, the dead area is about 4% at maximum CHIPY and about 2% at the readout. It is smaller for subarrays.

The ACIS clocking parameters required to scale the coefficients in the dafile are contained in the observation-specific parameter block file, which can be set by the associated parameter of this took, "pbkfile". If dafile=NONE, then pbkfile=NONE is assumed.

The dafile parameter is ignored for HRC data.

For Chandra, the mirror parameter must be set to "HRMA". However, the following ARDLIB qualifiers are also supported:

AREA=value
SHELL=value (possible values: 1,3,4,6)
BITMAP=value

For example, to compute an instrument map for using shells 1 and 3, which corresponds to the bitmap "1100", use "HRMA;bitmap=1100" for the value of this parameter. To compute using a mirror area of 1, use "HRMA;AREA=1".

The name of the parameter file to be used by ARDLIB.

The tool-specific parameter file contains no explicit CALDB parameters. Instead, the CALDB parameters are all contained in a separate parameter file selectable using the `ardlibparfile' parameter; "ardlib.par" is the default file name. Calibration files are specified implicitly via the `DetSubsys' and `Mirror' parameters described below.

The verbosity level for messages.

If set to yes, existing output files will be overwritten.