;SERCH ;--------------------------------------------------------------- ;! Finds line signals in transposed data cube ;# TASK SPECTRAL ANALYSIS ;----------------------------------------------------------------------- ;; Copyright (C) 1997, 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 ;----------------------------------------------------------------------- SERCH LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC SERCH Finds line signals in a v-x-y transposed image cube INNAME Input image name (name) INCLASS Input image name (class) INSEQ 0.0 9999.0 Input image name (seq. #) INDISK 0.0 9.0 Input image disk unit # BLC Bottom left corner of input TRC Top right corner of input YINC 0.0 64. Pixel increment on Y axis (usually right ascension) ZINC 0.0 64. Pixel increment on Z axis (usually declination) BCHAN 0.0 Lowest width in channels ECHAN 0.0 Highest width in channels CHINC 0.0 Increment in widths CHANSEL Up to 10 sets of begin, end and increment channel numbers for line search regions PIXAVG Estimate of average offset from 0 of non-signal areas PIXSTD Estimate of true noise rms NBOXES 0.0 40.0 Number of spectral regions to be used in fitting baseline 0 => no baseline fit BOX 0.0 4096.0 Pairs of begin-end channels for spectral baseline regions ICUT Report all "signals" with Signal/noise over ICUT. 0 => 8 DOWEIGHT -1.0 1.0 > 0 => use filters weighted by channel rms's, otherwise use unweighted filter DOOUTPUT -1.0 1.0 > 0 => write hyper cube of S/N > ICUT and < -ICUT. OUTNAME Hyper cube name OUTCLASS Hyper cube class OUTSEQ 0.0 Hyper cube sequence number OUTDISK 0.0 Hyper cube disk number DOHIST > 0 => plot/print histogram = 0 => print histogram < 0 -> no histogram FUNCTYPE 'LG' => do log10 plot of # samples, else linear LTYPE -10.0 10.0 Type of labeling: 1 border, 2 no ticks, 3 - 6 standard, 7 - 10 only tick labels <0 -> no date/time OUTTEXT Name of output log file, No output to file if blank DOTV -1.0 1.0 > 0 Do plot on the TV, else make a plot file GRCHAN 0.0 8.0 Graphics channel 0 => 1. BADDISK Disk to avoid for scratch ---------------------------------------------------------------- SERCH Task: Searches through a transposed data cube to try to find a line signal. It loops over the expected line width (from BCHAN to ECHAN by CHINC) convolving each spectrum with a Gaussian of the current width and reports all channels/pixels having signal-to-noise over ICUT. It accumulates a histogram of the S/N ratios and will plot it if requested. It can write a lot of information to a text file including the noise levels in each channel, the reported points, and the histogram. Based on an algorithm due to Juan Uson. Adverbs: INNAME.....Input image name (name). Standard defaults. INCLASS....Input image name (class). Standard defaults. INSEQ......Input image name (seq. #). 0 => highest. INDISK.....Disk drive # of input image. 0 => any. OUTSEQ.....Output image name (seq. #). 0 => highest unique. BLC........Bottom right corner in input image of desired subimage. Default is entire image. TRC........Top right corner in input image of desired subimage. Default is entire image. YINC.......Pixel increment kept from input Y axis (which is usually right ascension). 0 => 1. ZINC.......Pixel increment kept from input Z axis (which is usually declination). 0 => 1. BCHAN......Lowest line width tested in channels: 0 -> 2. ECHAN......Highest line width tested in channels: 0 -> 10. CHINC......Increment in line widths tested in channels; 0 -> 2. BCHAN, ECHAN, and CHINC do not have toi have integer values. CHANSEL....Up to 10 sets of begin/end/increment channel numbers to be tested for line signal. CHANSEL(1,*) = 0 => 1 CHANSEL(2,1) = 0 => NCHAN, CHANSEL(3,*) = 0 => 1. Other CHANSEL(2,*) = 0 => ignore this set. N.B. channel numbers are counted from 1 wrt to BLC(1). PIXAVG.....Estimate of average non-signal flux in image. PIXSTD.....Estimate of non-signal (true) rms in image. IMSTAT - or better IMEAN - can provide these. SERCH finds the true rms and average in each spectral channel, but will converge faster with good initial guesses. NBOXES.....Number of channel ranges to be used to find and subtract a linear spectral baseline on a point-by-point basis. 0 -> no baseline is subtracted. BOX........Up to 20 begin/end channels used to fit the linear spectral baseline. N.B. channel numbers are counted from 1 wrt to BLC(1). ICUT.......A flux cutoff in signal-to-noise ratio for reporting apparent signals. if abs(S/N) >= ICUT it is reported and, if DOOUTPUT is true, written to the output file. 0 -> 8. DOWEIGHT...The solutions may be determined by weighting each channel equally (DOWEIGHT <= 0) or inversely to the square of its rms (DOWEIGHT > 0). DOOUTPUT...If > 0, an output file of siognal-to-noise will be written. All S/N less in absolute value than ICUT will be written as zero. If the input file has N axes with > 1 pixel on them, then the output file will have its N+1 axis used for tested line width in channels. OUTNAME....Output file name. Default is INNAME. OUTCLASS...Output file class. Default is SERCH. OUTSEQ.....Output file sequence number. 0 -> one greater than previous maximum. OUTDISK....Output file disk number. DOHIST.....Determines whether a histogram is determined and plotted and/or printed. < 0 => no histogram, >= 0 => print histogram iff OUTTEXT is not blank, > 0 => plot histogram. FUNCTYPE...Type of axis plot for number of samples in each box. 'LG' => log base 10, else linear. LTYPE......Labelling type: 1 = border, 2 = no ticks, 3 - 10 = standard, with 7-10 all labels other than tick numbers and axis type are omitted. Less than 0 is the same except that the plot file version number and create time are omitted. OUTTEXT....Output file to log histograms, results, sigmas, etc. for later user processing. The file is created if it does not exist and appended to if it already exists. Nothing is is written to a file if the name is blank. File name should contain directory and file parts, i.e, "LOCAL:SERCH.OUT". DOHIST must be >= 0 for the file to contain the histogram. DOTV.......> 0 => plot directly on the TV device, otherwise make a plot file for later display on one or more devices (including the TV if desired). Only if DOHIST > 0. GRCHAN.....Graphics channel (1 - 7) to use for line drawing. 0 => 1. BADDISK....Disk drives to avoid for scratch file. ----------------------------------------------------------------