CREATE/PARFIL

 

This is a general EXSAS command which is used to generate dummy parameter files related to different tasks. When the task CORR is specified, a dummy Correction parameter file of any specified name is created (if a file with that name already existed, it would be overwritten). To create a parameter file is only necessary for correction tasks which are wished to be run independently from Projection. If an expert flag is not specified, the parameter file would include plenty of explanatory comment lines, in order to make it easy to fill in the parameter file entries.

The following entries are available in the correction parameter file:

• CORRECTION_MODE: it defines the mode under which the correction procedure should be run. It can be set either to attitude or to photon mode.
• ATTITUDE_FILE: it defines the name of the attitude file to be used when the CORRECTION_MODE is set to attitude.
• PHOTON_EVENT_TABLE: it defines the name of the photon event table to be used when the CORRECTION_MODE is set to photon.

  A photon event table having a sky map structure is forbidden. Usually the ROD photon event table has such a structure. The correction procedure requires a photon event table sorted in time, but time sorting would destroy the sky maps. Therefore it is advisable to select a sub-photon event table, containing at least the relevant photons (those used in creating the binned dataset) from the original one.  

  In the photon event table used in the correction procedure in photon mode, there must be contained at least the photons which contributed to the binned dataset to be corrected.

• OFF_AXIS_HISTOGRAM_BIN_SIZE: used in the PSPC and HRI data correction only. It defines the binsize for the off axis histogram which is produced during the correction procedure. It is expressed in arcminutes, defaulted to 1. We found that there is no point in modifying this parameter -- the execution time does not practically change -- so leave it as it is.
• DETECTOR_HISTOGRAM_PIXEL_SIZE: used in the WFC data   correction only. It defines the pixel for the detector histogram which is produced during the correction procedure. It is expressed in detector pixels, defaulted to 1. We found that there is no point in modifying this parameter -- the execution time does not practically change -- so leave it as it is.
• DATA_TO_BE_CORRECTED: the name of the table containing the data to be corrected is specified here. By default the data are assumed to be located at the first data column of the table. Differently, a column label must be specified: it must be separated from the table name by a comma (,) (for instance, mytable,mylabel). Following the MIDAS notation, the label name might be preceded by a colon (as in mytable,:mylabel).
• REPRESENTATIVE_SPECTRUM: in order to make an accurate light curve correction, the name of a table containing a typical spectrum of the source from which the light curve was derived must be specified here. Not specifying a spectral shape in the light curve correction affects heavily the vignetting correction, and the result is generally garbage.     This parameter is ignored in the spectral correction.
• SOURCE_X_SKY_COORDINATE, SOURCE_Y_SKY_COORDINATE: sky pixel coordinates of the fixed point of the sky which is taken in consideration in attitude mode (usually the location of a point source). In photon mode this entry is ignored. The sky coordinates can be omitted even in attitude mode, when the data to be corrected where selected from a circular portion of the sky: in this case the sky pixel coordinates will correspond by default to the center of this circle. In all other cases the source coordinates have to be specified.
• EFFECTIVE_AREA_CORRECTION_TABLE: name of the table containing the instrument effective area as a function of energy and detector position. The effective area correction is compulsory. In the ROSAT-PSPC case the table EXSAS_CAL:effarea_pspcb.tbl and EXSAS_CAL:effarea_pspcc.tbl are available. In the ROSAT-HRI case the effective area is given in the table EXSAS_CAL:effarea_hri.tbl.
• FILTER_TRANSMISSION_CORRECTION_TABLE: name of the table containing filters transmission as a function of photon energy. When no filter correction is required, this parameter must be removed (or commented out) from the parameter file. In the ROSAT-PSPC case the Boron filter data are located at the last column of the effective area correction table. When more than one filter column is present, the column label must be specified.  
• PSF_CORRECTION_IMAGE: name of the correction image   which is necessary in the PSF correction. In the ROSAT-PSPC case such an image can be created via the command CREATE/PSF (see section 4.3.6), using the latest models available for the PSPC or HRI PSF. A standard PSF correction image is also stored in the EXSAS calibration file EXSAS_CAL:psf_pspc.bdf. When the PSF correction is not requested, this parameter must be removed (or commented out) from the parameter file. PSF correction is applicable only for point-like sources centered within a circular sky selection.
• LIFE_TIME_CORRECTION_TABLE: correction table containing the house-keeping data which are necessary for the evaluation of the dead time. When the dead time correction is not requested, this parameter must be removed (or commented out) from the parameter file. This table is normally coming with the data, in the table eventrates.tbl.    
• OUTPUT_CORRECTION_TABLE: in the spectral correction the name of the output table containing the correction vector can be given. When the table name is not specified this parameter must be commented out. By default, the name would be the same of the table specified in DATA_TO_BE_CORRECTED, followed by the 2 characters _c.

  In the light curve correction the label of the output column containing the correction vector can be specified. This column is created in the same table containing the light curve to be corrected, which is specified at the entry DATA_TO_BE_CORRECTED. When the column label is not specified this parameter must be commented out. By default the output column takes the name from the label of the column containing the light curve to be corrected, preceded by the 2 characters C_.