polverify -- Verify calibrations of polarization efficiency and position angle offset.
polverify intable outtable type
This task verifies the polarization and its position angle for any number of targets from up to 20 apertures. The polarization and its position angle of any target at a given aperture is calculated from measurements at three different roll angles. This task uses the same equations as the poleffv task to calculate the Stokes parameters (Q, U, and intensity). (See the help file for poleffv for details.) The distribution of roll angles should be such that they cover more than 90 degrees; ideally, they should be 60 degrees from one another. For the same aperture, more than one measurement may be taken at the same roll angle. Also, for the same aperture, input data must have the same target, and be obtained at roughly the same temperature and epoch. The maximum number of input data points is 2,000.
Before actually performing the calculation, the raw digital count rates must be corrected for the dark signal, pre-amp noise, high voltage factor, and dead time:
scaled digital count rate = (raw digital count rate / (1. - raw digital count rate * dead time) - dark signal - pre-amplifier noise) / (high voltage factor * relative sensitivity)If analog data is used, then the raw data should be corrected as follows:
scaled analog count rate = ((raw analog DN - CVC offset) / gain factor - pre-amplifier noise - dark signal) / (high voltage factor * relative sensitivity)
- intable [file name]
- Name of the input table. The following columns are needed:
'DETECTOB' Object detector ID (int). 'APERTOBJ' Object aperture name (char*10). 'VOLTAGE' High voltage setting (real). 'VGAIND' Gain setting (real). 'THRESH' Discriminator setting (real). 'DET_TEMP' Detector temperature (real). 'DEA_TEMP' DEA temperature (real). 'EPOCH' Epoch of observation (double). 'PTSRCFLG' Point source flag (char*1). For digital data, the following columns are also needed: 'DOBJ' Digital count rate (real). 'DOBJ_ERR' Mean error of digital count rate (real). For analog data, the following columns are also needed: 'AOBJ' Analog reading (real). 'AOBJ_ERR' Mean error of analog reading (real). The 'polverify' task also needs the following columns: 'PA_APER' Position angle of the aperture (real). 'TRGTNAME' Target name (char*20).
- outtable [file name]
- Name of the output table produced by polverify; this table will
have the following columns:
'APER_NAME' Aperture name (char*10). 'P' Observed polarization in PERCENT (real). 'THETA' Position angle in equatorial system, unit is in decimal degrees (real). 'I' Intensity of the target (real). 'REF_P' Reference polarization (real). 'REF_THETA' Reference position angle (real). 'TEMPAVE' Average temperature (real). 'EPOCHAVE' Average epoch (double). 'TRGTNAME' Target name (char*20).
- type = "digital" [string, allowed values = "analog | digital"]
- Input data type.
- refpol [file name]
- Name of the standard polarization target table; this table has the
'OBJ_NAME_i' Name(s) of the object, where "i" is an integer between 1 and 5 (char*20). 'FILTER_NAME' Filter name, e.g., F551 (char*4). 'P' Polarization of the target in PERCENT (real). 'THETA' Polarization position angle of the target in equatorial system, and in degrees (real).
- pol_eff [file name]
- Name of the polarization efficiency calibration table, which has the following
'APER_NAME' Aperture name (char*10). 'PEFF' Polarization efficiency (real).
- pa_offset [file name]
- Name of the position angle offset calibration table, which has the
'FILTER_NAME' Filter name (char*4). 'DTHETA' Position angle offset (real).
- (cal_tables = "") [string]
- Pset name for calibration file parameters. Parameters can be individually changed from the command line or can be edited as a group using :e from eparam or from the cl, eparam cal_tables or simply cal_tables. Details about these parameters are available by typing "help cal_tables".
- (save = no) [boolean]
- Save the scratch table containing intermediate
If save = yes, a message will be sent to the terminal and the logfile indicating the file name of the intermediate calibrations.
- (temp_key = "DET_TEMP") [string]
- Column name of the temperature in the input table.
1. Verify polarization calibrations from the input data table xpolverify$input and put results in the output table ypolverify$output, while saving the intermediate result in another local table whose name will be announced to the user. Data type is digital. The reference polarization target table to be used is xpoleffv$refpol, the polarization efficiency table is xpolpav$pol_eff, and the position angle offset table is xpolverify$pa_offset.
hs> polverify "xpolverify$input" "ypolverify$output" "digital" \ >>> "xpoleffv$refpol" "xpolpav$pol_eff" "xpolverify$pa_offset" save=yes