The name of file containing the binned aspect history in the form of an aspect histogram (see asphist).

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

Variations in the the mirror effective area are assumed to be small on the scale of the dither pattern. Hence, the mean aspect offsets will be used to deduce the mirror effective area. This means that the aspect offsets should be small, typically less than 100 ACIS sky pixels (50 arcsec) in magnitude.

The name of the grating ARF file that this program will generate.

The diffraction order. The magnitude is limited by the orders' efficiencies tabulated in the calibration database grating files. (-11 to +11 for HEG and MEG, and -25 to 25 for LETG).

These parameters specify the (x,y) sky position of the point source, in the appropriate tangent plane pixel system for the detector. This should be the same as the zero-order centroid in the region used by tg_resolve_events for the source, and which are tabulated in the binned spectrum file (`pha2.fits').

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"

To use an ASCII file which contains two columns, the energ_lo and energ_hi, use:

"engrid=grid(myfile.tbl)"

Note that the preferred grid is linear in wavelength, since this reflects the natural dispersion of photons onto the detector. For back-compatibility, we write the grid in energy units in ascending order. To get a linear-wavelength grid, the first or third engrid forms must be used. Energy grids are required to be in ascending order.

The name of the FITS file that contains information about the observation via FITS keywords. This file should contain keywords that specify the mission, detector, SIM offsets, etc. The aspect histogram file should contain all the observational information. A level 1 event file will also suffice.

This parameter is used only when computing an ARF for an ACIS chip. Its value specifies the name of the order sorting table used extract nth order counts based upon the spatially dependent PHA fractions associated with the extraction region. "OSIP" stands for "Order Sorting and Integrated Probability". A value of "NONE" may be used to indicate that no such file is to be applied. If "NONE" is used, the it is assumed that the integrated probability is 1.0. The value, CALDB, indicates that the highest version for the most recent date before the observation date will be retrieved from the calibration data base.

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 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 chip or MCP of the detector for which the exposure map 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

The following qualifiers or options are supported for these detectors:

QE=value
IDEAL (equivalent to QE=1)
WINDOW=xmin,ymin,xmax,ymax
REGION=BOX(xcenter,ycenter,xsize,ysize)
REGION=RECTANGLE(xmin,xmax,ymin,ymax)

Note that only simple rectangular regions are supported.

For ACIS, one may select filter bad pixels based upon the status column in the bad pixel files by using the BPMASK qualifier:

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.

The grating arm to be used. The value of this parameter must be one of "HEG", "MEG", or "LEG".

For Chandra (a.k.a. AXAF), 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 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.

The name of the parameter file to be used by ARDLIB. Typically, "ardlib.par" will be used.

The parameter file contains only one explicit CALDB parameter (osip). Other such parameters are contained in ardlib.par. This parameter file is selectable using the `ardlibparfile' parameter. Calibration files are specified implicitely via the `DetSubsys' and `Mirror' parameter described below. Most default to CALDB, but can be made explicit for customized use.

The verbosity level for messages.

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