AIPS NRAO AIPS HELP file for ROBUST in 31DEC25



As of Mon Feb 10 9:55:24 2025



HELP SECTION

ROBUST
Type: Adverb   (Real)
Use:  The robustness parameter, devised by Daniel Briggs, is
      used to temper the effects of uniform weighting.  Thus,
      the weight actually used for sample i is
                             F1 (Wi)
              WT  =   ----------------------
                        [F2 (Wj)]   +    S
      where F1 and F2 are 2 functions applied to the input
      weights (Fi (W) = W by default), the [ ] means the sum of
      the F2 of the Weights of all samples in the neighborhood
      of the i'th sample, and S is a function of ROBUST.  We use
                      (10**(ROBUST)) * <[F2 (Wj)]>
              S  =   --------------------------------
                                    5
      where < > denotes the average of the local sums over all
      visibilities.  Note that if ROBUST > 4, the weight sums
      have little effect and the weighting is close to natural
      weighting.  If ROBUST < -4, then S is very small and we
      have virtually pure uniform weighting with no tempering.
Null value:   NONE
Tasks:
   IMAGR.........Fourier transform and Clean UV data with a full range of
                 calibration (application), weighting, Cleaning, and
                 wide-field correction options.
   SCIMG.........Full-featured imaging plus self-calibration loop with
                 editing.
   SCMAP.........Imaging plus self-calibration loop with editing.
   UVIMG.........Grid UV data into an "image".  If DOROBUST > 0, then
                 uniform weighting with AIPS standard ROBUST is done.
Procedures:
   CXIMAGR.......Grid UV data into a complex image, Fourier transform,
                 Clean - calls UVIMG.
   LINIMAGE......Build image cube from multi-IF data set.
   MAPPR.........Simplified access to IMAGR.
   OBITIMAG......Access to OBIT task Imager without self-cal or peeling.
   OBITMAP.......Simplified access to OBIT task Imager,
   OBITPEEL......Access to OBIT task Imager with self-cal and peeling.
   OBITSCAL......Access to OBIT task Imager with self-cal, NOT peeling.
   TDSTEP3.......Time-dependent imaging procedure "step 3"
   TDSTEP5.......Time-dependent imaging procedure "step 5"
   Y2KSAVE.......Verifies correctness and performance using standard
                 problems.

EXPLAIN SECTION


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