Version 4 (modified by 15 years ago) (diff) | ,
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Instructions for operating the Parkes continuum polarimetry software.
The data are acquired from the pulsar Digital Filter Bank correlator in "rpfits" format and are written to the area /DATA/PKCCC2_1/corr/dat/.
Sequence of Operations
Three files are necessary before the process can begin.
- freqtab.dat lists the centre frequencies (in MHz) of channels in the final output data.
- feed.dat is used to transform raw data to Stokes vectors (in the telescope frame). It defines the transformation in terms of reordering and sign changes.
- 3c138Flux.dat tabulates the frequency dependence of the flux and polarization characteristics of the polarized calibrator (3c138, B0637-75, ...).
These files should be in the working directory. Copies of the first two will be assigned to each data file being processed. The 3c138Flux.dat (or 0637Flux.dat) file will remain in the working directory and is found by the srcnam call in psolve.
Reduce the bandpass calibrator data
- Load the rpfits file into "parkespol" format.
pload 1934.rpf # # This will create a directory 1934/ and # with contents # -rw-r--r-- 1 mcc381 atculg 2355200 Feb 1 22:23 data.rpf # -rw-r--r-- 1 mcc381 atculg 204 Feb 2 11:06 feed.dat # -rw-r--r-- 1 mcc381 atculg 646 Feb 2 11:06 freqtab.dat
The original rpfits file is maintained so you will have two copies of the data.
- Perform the bandpass calibration
bpass 1934
Reduce the phase calibrator data
- Load the rpfits file
pload 2006-11-20_1401_3c138_Cal_DEC.rpf
- Copy the bandpass tables
gcopy 2006-11-20_1401_3c138_Cal_DEC 1934
- Extract the phase vs parallactic angle information from scans of the polarised calibrator
polcalr 2006-11-20_1401_3c138_Cal_DEC
- Determine polarisation parameters (leakages and phase difference between the signals from the two polarization channels) of the system from the phase data
psolve 2006-11-20_1401_3c138_Cal_DEC 3c138 /xs
To get a consistent pair of output files, the procedure needs to be executed twice. An example follows.
polcalr 2006-11-20_1401_3c138_Cal_DEC psolve 2006-11-20_1401_3c138_Cal_DEC 3c138 /xs polcalr 2006-11-20_1401_3c138_Cal_DEC 3c138 psolve 2006-11-20_1401_3c138_Cal_DEC 3c138 /xs
Reduce the astronomical data
- Load the rpfits file
pload source.rpf
- Copy the bandpass tables and polarisation corrections
gcopy source 1934 3c138
- Apply the calibrations and write results as a single-dish FITS file.
calscans.pl list
where list is a list of the data files to be calibrated.
If calscans is executed successively with the same outfile named it appends data from each execution into that file.
What calscans does: (check that this desription is correct)
- Reads the rpfits file;
- apply the bandpass calibration;
- transform to Stokes vectors;
- correct for instrumental phase;
- reorder the DFB output bins;
- properly label scan data with interpolated sky positions;
- average into final frequency channels;
- apply leakage calibration (if file polparams.dat is present);
- write out in sdfits format.
What calscans does not do (but could with some small software changes):
- Subtract baselines scan data;
- rotate Q,U from telescope to sky coordinates.