; UVSRT ;--------------------------------------------------------------- ;! Sort a UV dataset into a specified order ;# TASK UV CALIBRATION ;----------------------------------------------------------------------- ;; Copyright (C) 1995, 2001, 2008 ;; 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 ;----------------------------------------------------------------------- UVSRT LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC UVSRT: Task which sorts UV data INNAME Input UV file name (name) INCLASS Input UV file name (class) INSEQ 0.0 9999.0 Input UV file name (seq. #) INDISK Disk unit # of input UV data OUTNAME Sorted UV file name (name) OUTCLASS Sorted UV file name (class) OUTSEQ -1.0 9999.0 Sorted UV file name (seq. #) OUTDISK Disk unit # of sorted UV data 0 => highest with space If outfile spec. equals the infile spec., output will overwrite the input BADDISK Disk drive #'s to avoid SORT Two char. sort order, eg.'XY' blank => 'XY' ROTATE -360.0 360.0 Angle thru which to rotate. positive rotates CCW DEFER -1.0 1.0 Defer output file creation? ---------------------------------------------------------------- UVSRT Type: Task Use: To sort UV data into a specified order. The data are sorted into ascending values of the two keys (two are always used in the sort). NOTE: this task does NOT apply flagging or calibration tables to the input UV data. Run SPLIT first if that operation is desired. Adverbs: INNAME.....Input UV file name (name). Standard defaults. INCLASS....Input UV file name (class). Standard defaults. INSEQ......Input UV file name (seq. #). 0 => highest. INDISK.....Disk drive # of input UV. 0 => any. OUTNAME....Output UV file name (name). Standard defaults. OUTCLASS...Output UV file name (class). Standard defaults. OUTSEQ.....Output UV file name (seq. #).0 = > highest unique. OUTDISK....Disk drive # of output UV. 0 => highest with space If the outfile specification equals the infile specification, the output data file will overwrite the input data file. See DEFER below. BADDISK....Disk drive #'s of bad disks (for scratch files). SORT.......Sort order of output. blank => 'XY' and is the sort order needed for input to UVMAP. see HELP SORT for more information ROTATE.....Angle thru which to rotate map, positive is CCW. (degrees) rotation of the image. DEFER......True (> 0) means to defer the creation of the output file until the sort is complete and one of the 2 scratch files has been deleted. This allows a smaller the task to require disk space "only" two times that of the input file rather than three times required if the output does not overwrite the input. ---------------------------------------------------------------- UVSRT: Task which sorts UV data DOCUMENTOR: E.B.Fomalont (NRAO/VLA) RELATED PROGRAMS: UVLOD, UVMAP, ASCAL PURPOSE UVSRT will sort a UV data base into a specified order. The program is generally used after UVLOD and before UVMAP in order to sort the data from time-baseline order 'TB' into order of descending abs(u) spacing, which is designated as 'XY', needed for UVMAP. Before using ASCAL to self-calibrate a data base the UV sort order must be 'TB'. The order of the data base can be found by using the verb IMHEADER. After concatenation of data bases, UVSRT must be run to put the data into 'TB' or 'XY' order. This task does not use the array-processor but it is a very heavy user of the cpu power and disk space. If a data base of length N is sorted, it requires three areas of length N. Two areas are needed as scratch files and one is needed for the output data base. The latter can be avoided by overwriting the output onto the input. COMMENTS OUTNAME, OUTCLASS, OUTSEQ, OUTDISK: If the outfile specification is identical to the infile specification (including defaults used in both file specifications), then the sorted data will overwrite the input data. Make sure the input data set is properly backed up before you overwrite since a computer crash may destroy the input data set. SORT: The sort order is specified by two keys which are characters in the adverb SORT. The legal keys are: blank => X = descending ABS(u) B => baseline number T => time order U => u spatial freq. coordinate V => v spatial freq. coordinate W => w spatial freq. coordinate R => baseline length. P => baseline position angle. X => descending ABS(u) Y => descending ABS(v) Z => ascending ABS(u) M => ascending ABS(v) ROTATE: A positive number will rotate an image counter-clock-wise. That is, an image made from the sorted data with ROTATE=30 will produce an image which is rotated 30 degrees counter-clock-wise when compared with the image made from the sorted data with ROTATE=0. Map rotation is useful for orienting long, thin sources vertically or horizontally in order to permit smaller, rectangular maps to be made. This rotation cannot be done in UVMAP since it reorders the UV data. It is usually more convenient to orient the source with its long axis vertically rather than horizontally when using subsequent display software. DISKSPACE, BADDISK: UVSRT is clever enough to know if the amount of disk space is sufficient at the start of execution and this space is allocated immediately. If disk space is insufficient, writing the output data over the input data may help (as long as the input data set is backed-up properly). The working scratch file and the output data file need not be on the same disk. When other people are using a private disk pack, it is best to not use this pack for the scratch file since the private disk pack may be dismounted during your execution. Use BADDISK=N where N is the disk drive number to avoid this problem. TIMING: The program run time on an otherwise empty VAX 11-780 is 50 * (D/500,000) **1.1 minutes where D is the number of visibility points. All of the four Stokes parameters are sorted together.