Output

Directory structure

Factor produces the following output inside the working directory:

factor.log

Log file containing only the higher-level log messages. Detailed logs for each operation are available in the logs directory (see below).

factor_directions.txt

Optional file listing the DDE calibrators. This file is generated only when no directions file is supplied by the user.

chunks/

Directory containing the time-chunked datasets that Factor uses for processing.

logs/

Directory containing the detailed operation logs.

Note

The log of each operation is stored as logs/operation_name/direction_name.out.log. For example, the log of the facetselfcal operation for a direction named facet_patch_200 will be stored in logs/facetselfcal/facet_patch_200.out.log.

Note

Some error messages are stored in the logs/operation_name/direction_name.err.log file, but these are rarely of interest. Generally, important error messages will appear in the logs/operation_name/direction_name.out.log file. These log files can be very large, so a search for “error” is usually the easiest way to find any error messages.

regions/

Directory containing the ds9 region files for the facet and self-calibration images. The following region files are made:

• calimages_ds9.reg - the self-calibration image regions. The inner box shows the area over which sources are added back and cleaned. The outer box shows the area that is imaged.
• facets_ds9.reg - the facet image regions.

results/

Directory containing the results (images, etc.) of each operation. See Operations for details of the primary output products of each operation.

Note

The output of each operation is stored in a directory named results/operation_name/direction_name/. For example, the results of the facetselfcal operation for a direction named facet_patch_200 will be stored in results/facetselfcal/facet_patch_200/.

state/

Directory containing files that save the state of a reduction.

Final, primary-beam-corrected images

The final images for the processed facets (which may consist only of the target facet if image_target_only = True) are mosaicked together and corrected for the primary beam attenuation during the fieldmosaic operation (see fieldmosaic). The fieldmosaic operation produces the following images (in results/fieldmosaic/field/):

• *correct_mosaic.pbcor.fits - the primary-beam-corrected mosaic. This image should be used for measurements of the source flux densities.
• *correct_mosaic.pbcut.fits - the primary-beam-uncorrected (i.e., “flat-noise”) mosaic (blanked beyond 40% power point of primary beam). This image can be used as the detection image for source detection in PyBDSF.

See fieldmosaic for more details.

Self-calibration solutions and sky models

For each facet that undergoes self calibration, a set of self-calibration solutions and sky models are generated. These solutions and models are used to subtract or add sources in each facet. They are found in the facet directories under results/facetselfcal. See facetselfcal for more details.

Calibrated visibility data

For each facet that is imaged during the facetimage operation (see facetimage), a set of measurement sets are made that contain the calibrated visibilities for the facet. During the facetimage operation, the sources for the given facet are first added back (sources in the field that lie outside of the facet are not added back). Next, the visibilities are phase shifted to the facet center, the calibration for the facet is applied, and averaging is done (the amount of averaging allowed can be controlled with the max_peak_smearing parameter). These data are then used for the final imaging of the facet.

If you want to image the facet outside of Factor (e.g., by hand with CASA or WSClean), you can export these calibrated visibility data using archivefactor with the -d flag. For example, to export the calibrated data for a facet named facet_patch_468, run the following:

$ archivefactor factor.parset dir_output -d facet_patch_468

This command will create a directory inside dir_output named calibrated_data, inside of which will be measurement sets with the calibrated data (in the DATA column). Note that these data have not been corrected for the primary-beam attenuation but have had been corrected for the beam effects at the field phase center.

Residual data

The subtraction of sources in the residual datasets (originally produced by Prefactor) is improved during a Factor run. These datasets are those in the chunks/ directory. Normally, these data are not needed once a Factor run for a field is complete, but they are needed if the Factor run is later resumed. The archivefactor script will archive these datasets if the -r flag is used:

$ archivefactor factor.parset dir_output -r