polimg
Perform polarization imaging.
enable
bool
Execute the polimg worker.
label_in
str, optional, default = corr
Label of the .MS files to process.
rewind_flags
Rewind flags of the input .MS file(s) to specified version. Note that this is not applied to .MS file(s) you might be running “transfer_apply_gains” on.
enable
bool, optional, default = True
Enable segment rewind_flags.
mode
{“reset_worker”, “rewind_to_version”}, optional, default = reset_worker
If mode = ‘reset_worker’ rewind to the flag version before this worker if it exists, or continue if it does not exist; if mode = ‘rewind_to_version’ rewind to the flag version given by ‘version’ and ‘transfer_apply_gains_version’ below.
version
str, optional, default = auto
Flag version to restore. This is applied to the .MS file(s) identified by “label” above. Set to “null” to skip this rewinding step. If ‘auto’ it will rewind to the version prefix_workername_before, where ‘prefix’ is set in the ‘general’ worker, and ‘workername’ is the name of this worker including the suffix ‘__X’ if it is a repeated instance of this worker in the configuration file. Note that all flag versions saved after this version will be deleted.
overwrite_flagvers
bool, optional, default = False
Allow CARACal to overwrite existing flag versions. Not recommended. Only enable this if you know what you are doing.
ncpu
int, optional, default = 0
Number of CPUs used by WSClean. If set to 0 all available CPUs are used.
stokes
{“QU”, “QUV”, “IQU”, “IQUV”, “I”, “Q”, “U”, “V”}, optional, default = QUV
Stokes image to create. For this worker the options are “QU”,”QUV”,”IQU”,”IQUV”,”I”,”Q”,”U”,”V”. Before this step, we recomand to perform the I imaging with the selfcal worker and to do the polarization imaging on the self-calibrated MS.
make_images
make images
enable
bool, optional, default = True
List of options
minuvw_m
int, optional, default = 0
Exclude baselines shorter than this value (given in metres) from the imaging and self-calibration loop.
img_npix
int, optional, default = 1800
Number of pixels in output image.
img_padding
float, optional, default = 1.3
Padding in WSClean. Set to -1 if you do not want to disable.
img_gain
float, optional, default = 0.10
Fraction of the peak that is cleaned in each minor iteration. Set to -1 if you do not want to disable.
img_mgain
float, optional, default = 0.90
Gain for major iterations in WSClean. I.e., maximum fraction of the image peak that is cleaned in each major iteration. A value of 1 means that all cleaning happens in the image plane and no major cycle is performed.
img_cell
float, optional, default = 2.
Image pixel size (in units of arcsec).
img_weight
{“briggs”, “uniform”, “natural”}, optional, default = briggs
Type of image weighting, where the options are ‘briggs’, ‘uniform’, and ‘natural’. If ‘briggs’, set the ‘img_robust’ parameter.
img_robust
float, optional, default = 0.
Briggs robust value.
img_mfs_weighting
bool, optional, default = false
Enables MF weighting. Default is enabled.
img_taper
str, optional, default = 0.
Gaussian taper for imaging (in units of arcsec).
img_maxuv_l
float, optional, default = 0.
Taper for imaging (in units of lambda).
img_transuv_l
float, optional, default = 10.
Transition length of tukey taper (taper-tukey in WSClean, in % of maxuv).
img_niter
int, optional, default = 1000000
Number of cleaning iterations.
img_nmiter
int, optional, default = 0
Number of major cycles.
img_nchans
int, optional, default = 3
Number of channels in output image.
img_chan_range
str, optional, default = ‘ ‘
Channel range to be imaged. Comma-separated integer values.
img_joinchans
bool, optional, default = True
Join channels to create MFS image.
img_squared_chansjoin
bool, optional, default = True
Search peaks in the sum of Q^2 and/or U^2 image to clean. If ‘join-polarisations’ will set to True peaks will be search in the sum of Q^2+U^2.
img_join_polarizations
bool, optional, default = True
In combination with ‘img_squared_chansjoin’ will clean the image searching the peaks in the sum of Q^2+U^2.
img_specfit_nrcoeff
int, optional, default = 2
Number of spectral polynomial terms to fit to each clean component. This is equal to the order of the polynomial plus 1. Use 0 to disable spectral fitting. Note that spectral fitting is required if you want to do subsequent continumm subtraction using crystalball.
img_multiscale
bool, optional, default = False
Switch on multiscale cleaning.
img_multiscale_scales
str, optional, default = ‘ ‘
Comma-separated integer scales for multiscale cleaning in pixels. If set to an empty string WSClean selects the scales automatically. These include the 0 scale, a scale calculated based on the beam size, and all scales obtained increasing the scale by a factor of 2 until the image size is reached.
img_nrdeconvsubimg
int, optional, default = 0
Speed-up deconvolution by splitting the image into a number of subimages, which are deconvolved in parallel. This parameter sets the number of subimages as follows. If set to 1 no parallel deconvolution is performed. If set to 0 the number of subimages is the same as the number of CPUs used by the selfcal worker (see “ncpu” parameter above). If set to a number > 1 , the number of subimages is greater than or equal to the one requested by the user.
img_nwlayers_factor
int, optional, default = 3
Use automatic calculation of the number of w-layers, but multiple that number by the given factor. This can e.g. be useful for increasing w-accuracy. In practice, if there are more cores available than the number of w-layers asked for then the number of w-layers used will equal the number of cores available. Set to -1 if you do not want to disable.
col
str, optional, default = DATA, CORRECTED_DATA
Column(s) to image.
clean_cutoff
float, optional, default = 0.5
Cleaning threshold to be used by WSClean. This is given as the number of sigma_rms to be cleaned down to, where sigma_rms is the noise level estimated by WSClean from the residual image before the start of every major deconvolution iteration.
cleanmask_method
str, optional, default = wsclean
Method used to create the clean mask. The possible values are 1) ‘wsclean’ to use WSClean’s auto-masking (threshold set by clean_mask_threshold below); 2) a prefix string to use an existing .FITS mask located in output/masking and called name.fits.
cleanmask_thr
float, optional, default = 5.0
Threshold used to create the clean mask when WSClean. This is given as the number of sigma_rms to be cleaned down to, where sigma_rms is the (local) noise level. Set to -1 if you do not want to disable.
cleanmask_localrms
bool, optional, default = False
Use a local-rms measurement when creating a clean mask with WSClean. This local-rms setting is also used for the clean_threshold above. Otherwise it is only used to define the clean mask, and clean_threshold is in terms of the global noise (rather than the local noise).
cleanmask_localrms_window
int, optional, default = 31
Width of the window used to measure the local rms when creating the clean mask. The window width is in PSFs for clean_mask_method = ‘wsclean’.
weighting_rank_filter
float, optional, default = 3.
Filter the weights and set high weights to the local mean. The level parameter specifies the filter level; any value larger than level*localmean will be set to level*localmean.
absmem
float, optional, default = 100.0
Specifies a fixed amount of memory in gigabytes.
make_extra_images
make convolved images and/or PB images.
enable
bool, optional, default = False
List of options
schema
str, optional, default = both
specify if you want single channel images (single), cubes (cube), or both (both).
convl_images
bool, optional, default = False
Convolve output images to a common resolution
convl_beam
str, optional, default = ‘ ‘
Target beam for images. If empty the target beam is the channel zero beam. Otherwise set as ‘bmin, bmaj, bpa’ in deg units.
make_pb_images
bool, optional, default = True
Make PB images
flagging_summary
Output the flagging summary.
enable
bool, optional, default = False
Enable the ‘flagging_summary’ segment.
report
bool, optional, default = False
(Re)generate a full HTML report at the end of this worker.
cabs
list of map, optional, default = ‘ ‘
Specifies non-default image versions and/or tags for Stimela cabs. Running with scissors: use with extreme caution.