[daip] IMEAN can't get histogram fit.
Craig Walker
cwalker at nrao.edu
Wed Jun 25 16:16:36 EDT 2014
I am in a situation where I cannot get IMEAN to deliver a histogram fit,
which is my preferred way to measure image noise. As far as I can
tell, the problem is that the first guess is completely out to lunch.
IMEAN used to use input parameters as the first guess and that was a bit
of a pain. Now it uses ACTNOISE and ACTMEAN from the header. For this
case, somehow ACTNOISE and ACTMEAN got set to spurious values. I say
spurious because they are both higher than the image peak and are, based
on previous successful runs, about 2 orders of magnitude higher than
they should be. I tried to fix the situation by using PUTHEAD to change
ACTNOISE even though that is not in the list of parameters in EXPLAIN
PUTHEAD. The message that came back was
>go puthead
AIPS 1: UNKNOWN DATA TYPE =
AIPS 1: DATA TYPE?
So I guess I can't do that. So I'm stuck. I can't change the first
guess and with that first guess, IMEAN can't get a fit.
The image is on noatak, user 332 disk 3:
AIPS 1: 143 332 J1502P .ICL001. 2008 MA 25-JUN-2014 14:10:24
The header is:
AIPS 1: Image=J1502S (MA) Filename=J1502P .ICL001.2008
AIPS 1: Telescope=VLBA Receiver=VLBA
AIPS 1: Observer=BW102 User #= 332
AIPS 1: Observ. date=29-JUN-2013 Map date=24-JUN-2014
AIPS 1: Minimum=-9.19859449E-05 Maximum= 1.57862421E-04 JY/BEAM
AIPS 1: ----------------------------------------------------------------
AIPS 1: Type Pixels Coord value at Pixel Coord incr Rotat
AIPS 1: RA---SIN 1024 15 02 43.179 -3918.00 -0.000300 0.00
AIPS 1: DEC--SIN 1024 11 15 57.070 -587.00 0.000300 0.00
AIPS 1: FREQ 1 4.9804107E+09 1.00 1.9200000E+08 0.00
AIPS 1: STOKES 1 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: ----------------------------------------------------------------
AIPS 1: Coordinate equinox 2000.00
AIPS 1: Map type=NORMAL Number of iterations= 10
AIPS 1: Conv size= 0.00300 X 0.00131 Position angle= -3.63
AIPS 1: Phase shifted in X -1.35511 in Y 0.33000
AIPS 1: Rest freq 4884.000 Vel type: OPTICAL wrt YOU
AIPS 1: Alt ref. value 0.00000E+00 wrt pixel 0.34
AIPS 1: Maximum version number of extension files of type CC is 1
AIPS 1: Maximum version number of extension files of type CG is 1
AIPS 1: Maximum version number of extension files of type HI is 1
AIPS 1: Maximum version number of extension files of type MF is 1
AIPS 1: Maximum version number of extension files of type PL is 3
AIPS 1: Keyword = 'WTNOISE ' value = 1.20016982D+00
AIPS 1: Keyword = 'SUMWTIN ' value = 3.02665212D+03
AIPS 1: Keyword = 'CCFLUX ' value = 1.046534E-04
AIPS 1: Keyword = 'CCTOTAL ' value = 1.046534E-04
AIPS 1: Keyword = 'OLDRFQ ' value = 4.88400000D+09
AIPS 1: Keyword = 'CORRELAT' value = 'DIFX '
AIPS 1: Keyword = 'MAXABSU ' value = -1.000000E+00
AIPS 1: Keyword = 'SOURNAM1' value = 'J1502S '
AIPS 1: Keyword = 'SOURNAM2' value = ' '
AIPS 1: Keyword = 'ACTNOISE' value = 1.880905E-03
AIPS 1: Keyword = 'ACTMEAN ' value = 2.989471E-04
>
The puthead inputs are:
AIPS 1: PUTHEAD: Verb to modify image header parameters.
AIPS 1: Adverbs Values Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: INNAME 'J1502P' Image name(name).
AIPS 1: INCLASS 'ICL001' Image name(class).
AIPS 1: INSEQ 2008 Image name(seq. #). 0=>high
AIPS 1: INDISK 3 Disk drive #. 0=>any
AIPS 1: KEYWORD 'ACTNOISE' Name of header parameter.
AIPS 1: See EXPLAIN PUTHEAD for list.
AIPS 1: KEYVALUE 1.700E-05 0 Value given to numeric parm.
AIPS 1: = KEYVALUE(1) + KEYVALUE(2).
AIPS 1: KEYSTRNG ' ' Value given to a character-
AIPS 1: valued parameter.
AIPS 1: KEYTYPE ' ' Data type for new keyword
IMEAN inputs:
>inp imean
AIPS 1: IMEAN: Task to print the mean, rms and extrema in an image
AIPS 1: Adverbs Values Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: DOHIST 1 True (1.0) do histogram plot.
AIPS 1: = 2 => flux on x axis
AIPS 1: USERID 0 User ID. ignored
AIPS 1: INNAME 'J1502P' Image name (name)
AIPS 1: INCLASS 'ICL001' Image name (class)
AIPS 1: INSEQ 2008 Image name (seq. #)
AIPS 1: INDISK 3 Disk drive #
AIPS 1: BLC *all 0 Bottom left corner of image
AIPS 1: 0=>entire image
AIPS 1: TRC *all 0 Top right corner of image
AIPS 1: 0=>entire image
AIPS 1: DOINVERS -1 > 0 => histogram outside
AIPS 1: <=0 => inside BLC/TRC
AIPS 1: NBOXES 256 No. of ranges for histogram.
AIPS 1: PIXRANGE -2.00E-04 2.000E-04 Min and max range for hist.
AIPS 1: FUNCTYPE ' ' 'LG' => do log10 plot of #
AIPS 1: samples, else linear
AIPS 1: DOMODEL 1 > 0 fit, plot Gaussian
AIPS 1: DOCAT 1 Put true RMS in header
AIPS 1: LTYPE 4 Type of labeling: 1 border,
AIPS 1: 2 no ticks, 3 - 6 standard,
AIPS 1: 7 - 10 only tick labels
AIPS 1: <0 -> no date/time
AIPS 1: DOPRINT 0 0 - no print, -3 brief
AIPS 1: OUTTEXT *all ' ' Name of output log file,
AIPS 1: No output to file if blank
AIPS 1: DOTV 1 > 0 Do plot on the TV, else
AIPS 1: make a plot file
AIPS 1: GRCHAN 0 Graphics channel 0 => 1.
IMEAN results:
>go imean
AIPS 1: Waiting for returned adverbs
IMEAN1: Task IMEAN (release of 31DEC14) begins
IMEAN1: Initial guess for PIXSTD taken from ACTNOISE in header
IMEAN1: Guess is Mean= 2.9895E-04 Rms= 1.8809E-03
IMEAN1: Histogram fit for RMS fails: plot a histogram
IMEAN1: returns adverbs to AIPS
IMEAN1: Image= J1502P .ICL001.2008 3 xywind= 1 1 1024 1024
IMEAN1: Mean and rms found by including all data:
IMEAN1: Mean=-4.067E-09 Rms= 1.932E-05 JY/BEAM over 1048576. pixels
IMEAN1: Flux density = -8.6264E-05 Jy. beam area = 49.43 pixels
IMEAN1: Minimum=-9.1986E-05 at 1024 473 1 1
IMEAN1: Skypos: RA 15 02 43.0782181 DEC 11 15 57.388000
IMEAN1: Maximum= 1.5786E-04 at 511 515 1 1
IMEAN1: Skypos: RA 15 02 43.0886796 DEC 11 15 57.400600
IMEAN1: Skypos: IPOL 4980.411 MHZ
IMEAN1: Appears to have ended successfully
IMEAN1: noatak 31DEC14 TST: Cpu= 0.0 Real= 1 IO= 4
AIPS 1: Resumes
Suggestions?
Cheers,
Craig
--
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R. Craig Walker Array Operations Center
cwalker at nrao.edu National Radio Astronomy Observatory
Phone 575 835 7247 P. O. Box O
Fax 575 835 7027 Socorro NM 87801 USA
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