; STEER ;--------------------------------------------------------------- ;! Task which deconvolves the David Steer way. ;# TASK 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 ;----------------------------------------------------------------------- ;--------------------------------------------------------------- STEER LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC STEER : Task which deconvolves the David Steer way. Dirty image INNAME Image name (name) INCLASS Image name (class) INSEQ 0.0 9999.0 Image name (seq. #) INDISK 0.0 4.0 Image disk drive # Beam image IN2NAME Image name (name) IN2CLASS Image name (class) IN2SEQ 0.0 9999.0 Image name (seq. #) IN2DISK 0.0 4.0 Image disk drive # Steer image OUTNAME Image name (name) OUTCLASS Image name (class) OUTSEQ -1.0 9999.0 Image name (seq. #) OUTDISK 0.0 4.0 Image disk drive # GAIN -1.0 1.0 Steer loop gain NITER 0.0 32767.0 Maximum # of iterations DOTV -1.0 1.0 TV display of residuals? NBOXES 0.0 10.0 Number of boxes BOX 0.0 4096.0 Four coordinates for each box BADDISK -1.0 1000.0 Disks to avoid for scratch. OFFSET -1.0 1000.0 Trim level ---------------------------------------------------------------- STEER Type: Task Use: STEER deconvolves the dirty beam from the dirty map thus producing a map with the units of brightness (Jy/pixel). Conversion to other units e.g. KELVIN can be done with AXDEFINE. STEER may be restarted if further improvement is desired. This program is slow but should be comparable to APCLN if the map contains many picture elements. The task CONVL may be used to convolve the map to the resolution produced by a CLEAN program. The algorithm used in the program is due to David Steer. The principle is similar to Barry Clark's CLEAN except that in the minor cycle only points above the (trim level)*(peak in the residual map) are selected. In the major cycle these are removed using an FFT. If the BOXes are chosen to surround the source snugly then the algorithm will converge faster and will have more chance of finding a unique image. This is an experimental program; please relay any complaints etc. to Tim Cornwell at the VLA Adverbs: INNAME......The dirty image name. Standard defaults. INCLASS.....The dirty image class. Standard defaults. INSEQ.......The dirty image seq. #. 0 => highest. INDISK......The dirty image disk drive #. 0 => any IN2NAME.....The beam image name. blank => actual INNAME, otherwise standard defaults. IN2CLASS....The beam image class. Standard defaults except blank => 'RBEM' if INCLASS = 'RMAP' 'LBEM' if INCLASS = 'LMAP' 'IBEM' if INCLASS = anything else IN2SEQ......The beam image seq . #. 0 => actual INSEQ IN2DISK.....The beam image disk drive #. 0 => any OUTNAME.....The Steer image name. blank => Standard defaults based on INNAME. OUTCLASS....The Steer image class. Standard behavior with default = 'XGS ' if INCLASS = 'XMAP' OUTSEQ......The Steer image seq. #. 0 => highest unique If >0; image will be created if new, overwritten if image name exists. OUTDISK.....The Steer disk drive no. 0 => highest with space GAIN........The Steer loop gain. 0 => 0.01, for most cases 0.02 will work well. NITER.......Steer iteration limit. 0 => 20 DOTV........Display Steer map on TV channel 1. > 0 => yes. If true, you may stop the Steering with TV button D after each Steer map is displayed. NBOXES......The number of rectangular boxes. The Steer image is non-zero only within these boxes. 0=>1 BOX.........A 4x10 array with the BLC and TRC of each box. 0 => use inner quarter of input map (first box) 0 => ignore box (boxes 2 - 10) BADDISK.....This array contains the numbers of disks on which it is desired that scratch files not be located. BADDISK has no effect on input and output maps. OFFSET......The Trim Level. In a minor cycle only points above this fraction of the peak residual are selected. 0.8 works well. ----------------------------------------------------------------