; ROBUST ;--------------------------------------------------------------- ;! Uniform weighting "robustness" parameter ;# ADVERB UV IMAGING ;----------------------------------------------------------------------- ;; Copyright (C) 1995 ;; Associated Universities, Inc. Washington DC, USA. ;; ;; This program is free software; you can redistribute it and/or ;; modify it under the terms of the GNU General Public License as ;; published by the Free Software Foundation; either version 2 of ;; the License, or (at your option) any later version. ;; ;; This program is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; ;; You should have received a copy of the GNU General Public ;; License along with this program; if not, write to the Free ;; Software Foundation, Inc., 675 Massachusetts Ave, Cambridge, ;; MA 02139, USA. ;; ;; Correspondence concerning AIPS should be addressed as follows: ;; Internet email: aipsmail@nrao.edu. ;; Postal address: AIPS Project Office ;; National Radio Astronomy Observatory ;; 520 Edgemont Road ;; Charlottesville, VA 22903-2475 USA ;----------------------------------------------------------------------- ;--------------------------------------------------------------- ROBUST LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC ---------------------------------------------------------------- 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. ----------------------------------------------------------------