#
AIPS HELP file for ROBUST in 31DEC19

#### As of Wed Jan 23 20:15:13 2019

### 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, weighting, Cleaning, and
wide-field correction options.

### EXPLAIN SECTION