; AVSPC ;--------------------------------------------------------------- ;! Averages uv-data in the frequency domain ;# Task UV Spectral ;----------------------------------------------------------------------- ;; Copyright (C) 1995, 2000-2001 ;; 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 ;----------------------------------------------------------------------- AVSPC LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC AVSPC Task to average uv data in frequency. INNAME Input UV file name (name) INCLASS Input UV file name (class) INSEQ 0.0 9999.0 Input UV file name (seq. #) INDISK 0.0 9.0 Input UV file disk unit # OUTNAME Output UV file name (name) OUTCLASS Output UV file name (class) OUTSEQ -1.0 9999.0 Output UV file name (seq. #) OUTDISK 0.0 9.0 Output UV file disk unit #. ICHANSEL Array of start and stop chn numbers, plus a channel increment and IF to be used for channel selection in the averaging. See HELP ICHANSEL. Default = center 75% of band. AVOPTION Averaging option ' ','AVIF', 'SUBS' BIF 0.0 100.0 Lowest IF number (AVIF only) EIF 0.0 100.0 Highest IF number (AVIF only) FLAGVER Flag table version CHANNEL # chans to average together used when AVOPTION = 'SUBS' ---------------------------------------------------------------- AVSPC Task: Average a uv database in the frequency domain. The two principle uses of this task are to create a data base containing 'continuum' channels for use in calibrating spectral line observations and for averaging in frequency for continuum observations that don't require frequency resolution to reduce bandwidth smearing. For the purpose of forming a continuum data base from spectral line observations AVSPC has optional channel selection so channels may be omitted from the average if necessary. The default channel range that is averaged is the center 75%, this is what is used at the VLA to produce 'channel 0'. Averaging in IF as well as frequency is specified by AVOPTION='AVIF'. This should only be applied to previously calibrated data. This option is useful for continuum observations of relatively small fields of view where averaging in frequency and IF is desired to reduce the bulk of the data or for display purposes. All tables associated with the input data are copied to the averaged output data, however only the FG (flagging) table may be applied. The FG table is not copied since it has been applied and contains channel numbers which are no longer correct. 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 file. 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 file. 0 => highest with space for the file. ICHANSEL...Array of start and stop channels plus a channel increment and IF, used to select the channels to be averaged. For instance, if you wished to exclude channels 1 - 10 and 121 - 128 because of bandpass effects, and channels 56 - 80 of IF 1 but not IF 2 because of interference, then you would set ICHANSEL = 11,55,1,1, 81,121,1,1, 11,121,1,2. If you only wished to use every other channel from the second IF then you would set ICHANSEL = 11,55,1,1, 81,121,1,1, 11,121,2,2. Up to 20 groups of start, stop and increment channel numbers plus IF numbers can be specified. The default (ICHANSEL = 0) is to average the center 75% of the band, i.e. ICHANSEL(1,1) = (# channels)/8 ICHANSEL(2,1) = (# channels + 1)*7/8 ICHANSEL(3,1) = 1 ICHANSEL(4,1) = 0 (meaning all IFs). AVOPTION...The averaging option. ' ' means only average frequency channels for each IF separately. 'AVIF' means average BIF to EIF and write a single output IF. This option is most useful for averaging multi_IF continuum observations of a relatively small field of view. 'SUBS' means average every n channels of each IF together producing an output file of spectral size INT(input/n). Any excess channels from the input spectrum will be discarded. The number of channels to average together is specified by CHANNEL. E.g. AVOPTION = 'SUBS', CHANNEL = 8 on a 128 channel input file will produce 16 channels in the output file. The CHANSEL adverb is ignored when AVOPTION = 'SUBS' A boxcar average will be done of those channels to be averaged together. BIF........First IF to consider. 0=>all. Used only by AVIF option. EIF........Highest IF to consider. 0=>all higher than BIF. Only used for AVOPTION='AVIF' FLAGVER....specifies the version of the flagging table to be applied. 0 => highest numbered table. <0 => no flagging to be applied. CHANNEL....The number of channels/IF to average together when AVOPTION = 'SUBS'. i.e., channel = # input channels / # output channels ----------------------------------------------------------------