[daip] IMAGR bug
Crystal Brogan
cbrogan at nrao.edu
Mon Jun 9 17:59:18 EDT 2008
Hi,
There appears to have been a bug introduced in IMAGR during the weekend
update. I am using the computer shadowfax in CV.
Attached is a single uv channel (channel 90) of a VLA 44 GHz dataset. The
masers in this channel are very strong (~300 Jy).
If I clean the image as follows below with AIPS version='TST', when the
min allowed flux reaches
Field 1 min allowed flux = -534.402 MilliJy
It goes into an infinite loop where the min flux does not change but the
total cleaned flux continues to grow and grow until the niter is reached.
The exact min. flux where this happens varies but it happens for several
very strong maser channels (the rms noise in a maser free channel is ~60
mJy - the strong masers are very much dynamic range limited). If I do NOT
use clean boxes, the flux threshold is reached without a problem.
So the problem appears connected with the use of clean boxes.
If I use version='old' WITH clean boxes (as specified below), the image
cleans to 300 mJy with no abnormal behavior.
AIPS 1: IMAGR: Wide field imaging/Clean task
AIPS 1: Adverbs Values Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: INNAME '17209-35451' Input UV data (name)
AIPS 1: INCLASS 'CH90' Input UV data (class)
AIPS 1: INSEQ 1 Input UV data (seq. #)
AIPS 1: INDISK 3 Input UV data disk drive #
AIPS 1: SOURCES *all ' ' Source name
AIPS 1: QUAL -1 Calibrator qualifier -1=>all
AIPS 1: CALCODE ' ' Calibrator code ' '=>all
AIPS 1: TIMERANG *all 0 Time range to use
AIPS 1: SELBAND -1 Bandwidth to select (kHz)
AIPS 1: SELFREQ -1 Frequency to select (MHz)
AIPS 1: FREQID -1 Freq. ID to select.
AIPS 1: SUBARRAY 0 Sub-array, 0=>all
AIPS 1: ANTENNAS *all 0 Antennas to plot
AIPS 1: BASELINE *all 0 Baselines with ANTENNAS
AIPS 1: DOCALIB -1 > 0 calibrate data & weights
AIPS 1: > 99 do NOT calibrate weights
AIPS 1: GAINUSE 0 CL (or SN) table to apply
AIPS 1: DOPOL 0 If >0.5 correct polarization.
AIPS 1: BLVER 0 BL table to apply.
AIPS 1: FLAGVER 0 Flag table version
AIPS 1: DOBAND 0 If >0.5 apply bandpass cal.
AIPS 1: Method used depends on value
AIPS 1: of DOBAND (see HELP file).
AIPS 1: BPVER 0 Bandpass table version
AIPS 1: SMOOTH *all 0 Smoothing function. See
AIPS 1: HELP SMOOTH for details.
AIPS 1: STOKES ' ' Stokes parameters (see HELP)
AIPS 1: BCHAN 90 Low freq. channel 0 for cont.
AIPS 1: ECHAN 90 Highest freq channel
AIPS 1: CHANNEL 0 Restart channel number
AIPS 1: NCHAV 0 Number of chan. to average.
AIPS 1: CHINC 1 Channel incr. between maps.
AIPS 1: BIF 1 First IF in average.
AIPS 1: EIF 0 Last IF in average.
AIPS 1: OUTNAME ' ' Output image name (name)
AIPS 1: OUTDISK 3 Output image disk drive #
AIPS 1: OUTSEQ 0 Output seq. no.
AIPS 1: OUTVER 0 CC ver. no (Continuum only)
AIPS 1: *** SET OUTVER ON RESTARTS
AIPS 1: IN2NAME ' ' UV work file name
AIPS 1: IN2CLASS ' ' UV work file class
AIPS 1: IN2SEQ 0 UV work file seq
AIPS 1: *** SET TO KEEP WORK FILE
AIPS 1: IN2DISK 0 UV work file disk
AIPS 1: CELLSIZE 0.08 0.08 (X,Y) size of grid in asec
AIPS 1: IMSIZE 2048 2048 Minimum image size
AIPS 1: NFIELD 1 Number of fields (max 4096)
AIPS 1: DO3DIMAG 1 > 0 => use different tangent
AIPS 1: points for each field
AIPS 1: FLDSIZE *all 0 Clean size of each field.
AIPS 1: RASHIFT *all 0 RA shift per field (asec)
AIPS 1: DECSHIFT *all 0 DEC shift per field (asec)
AIPS 1: UVTAPER 0 0 (U,V) Gaussian taper
AIPS 1: units are kilo-lambda
AIPS 1: UVRANGE 0 0 Min & max baseline (klambda)
AIPS 1: GUARD 0 0 x,y guard band fractional
AIPS 1: radius
AIPS 1: ROTATE 0 Rotate image CCW from N by
AIPS 1: ROTATE degrees
AIPS 1: ZEROSP *all 0 0-spacing fluxes and weights
AIPS 1: SEE HELP!!
AIPS 1: UVWTFN ' ' UV dist. weight function
AIPS 1: UVSIZE 0 0 Array size for doing uniform
AIPS 1: weights. 0 -> actual field
AIPS 1: size.
AIPS 1: ROBUST 5 Robustness power: -5 -> pure
AIPS 1: uniform weights, 5 => natural
AIPS 1: UVBOX 0 Additional rows and columns
AIPS 1: used in weighting.
AIPS 1: UVBXFN 1 Box function type when UVBOX
AIPS 1: > 0. 0 -> 1 round pill box.
AIPS 1: XTYPE 5 Conv. function type in x
AIPS 1: default spheroidal
AIPS 1: YTYPE 5 Conv. function type in y
AIPS 1: default spheroidal
AIPS 1: XPARM *all 0 Conv. function parms for x
AIPS 1: YPARM *all 0 Conv. function parms for y
AIPS 1: NITER 1000000 Maximum # of Clean components
AIPS 1: BCOMP *all 0 Begin at BCOMP component
AIPS 1: Specify for each field.
AIPS 1: ALLOKAY 0 For restart: > 0 => beams
AIPS 1: okay, > 1 => work file too
AIPS 1: NBOXES 23 Number of boxes for Clean
AIPS 1: NB: field 1 only.
AIPS 1: CLBOX -1 12 Four coordinates for each box
AIPS 1: 958 1150 -1 12
AIPS 1: 946 1138 -1 12
AIPS 1: 988 1030 -1 9
AIPS 1: 982 1138 -1 12
AIPS 1: 1240 982 -1 12
AIPS 1: 1285 964 -1 9
AIPS 1: 1306 910 -1 18
AIPS 1: 1129 865 -1 15
AIPS 1: 1153 877 -1 12
AIPS 1: 1015 775 -1 12
AIPS 1: 943 808 -1 15
AIPS 1: 931 799 -1 15
AIPS 1: 1069 982 -1 15
AIPS 1: 1054 970 -1 12
AIPS 1: 1045 952 -1 12
AIPS 1: 1096 973 -1 12
AIPS 1: 793 742 -1 21
AIPS 1: 832 757 -1 21
AIPS 1: 853 778 -1 18
AIPS 1: 877 859 -1 12
AIPS 1: 955 1018 -1 12
AIPS 1: 985 1069 -1 18
AIPS 1: 751 388 *rest 0
AIPS 1: BOXFILE *all ' ' Input file of field params
AIPS 1: and Clean boxes; ' ' => use
AIPS 1: FLDSIZE, RASHIFT, DECSHIFT,
AIPS 1: NBOXES, CLBOX only.
AIPS 1: OBOXFILE *all ' ' Output file for final Clean
AIPS 1: boxes
AIPS 1: GAIN 0.1 Clean loop gain
AIPS 1: FLUX 0.3 Minimum Clean component (Jy)
AIPS 1: MINPATCH 121 Min. BEAM half-width in AP.
AIPS 1: BMAJ 0 FWHM(asec) major axis Clean
AIPS 1: restoring beam.
AIPS 1: BMIN 0 FWHM(asec) minor axis Clean
AIPS 1: restoring beam.
AIPS 1: BPA 0 Clean beam position angle
AIPS 1: OVERLAP 2 1 => restore components to
AIPS 1: overlapped fields, >=2=>
AIPS 1: expect overlaps in Cleaning
AIPS 1: PHAT 0 Prussian hat height.
AIPS 1: FACTOR 0 Speedup factor see HELP
AIPS 1: CMETHOD ' ' Modeling method:
AIPS 1: 'DFT','GRID',' '
AIPS 1: IMAGRPRM *all 0 Task enrichment parameters
AIPS 1: (1) Antenna diameter (m)
AIPS 1: (2) Source Spectral index
AIPS 1: (3) Frequency scaling factor
AIPS 1: (4) > 0 -> SDI Clean factor
AIPS 1: (5) >0 => scale residuals
AIPS 1: (6) Half-width in x of box
AIPS 1: (7) Half-width in y of box
AIPS 1: (8) Filter components whose
AIPS 1: neighborhood is weaker than
AIPS 1: IMAGRPRM(8) Jy. 0 -> don't
AIPS 1: (9) Radius in pixels for the
AIPS 1: IMAGRPRM(8) test.
AIPS 1: (10) multiplier of image size
AIPS 1: to get beam size: 0 => 2;
AIPS 1: 2, 1, 0.5 0.25 supported
AIPS 1: (11-16) Multi-resolution
AIPS 1: added controls
AIPS 1: (17) spectral index radius
AIPS 1: 0 -> no correction
AIPS 1: (19) Dynamic range limit
AIPS 1: (20) Retry factor (see help)
AIPS 1: NGAUSS 0 Number of resolutions to use
AIPS 1: WGAUSS *all 0 Resolutions in arc sec >= 0
AIPS 1: FGAUSS *all 0 Minimum flux for each resol.
AIPS 1: MAXPIXEL 60000 Maximum pixels searched in
AIPS 1: each major cycle.
AIPS 1: IN3NAME ' ' Spectral index image name
AIPS 1: IN3CLASS ' ' Spectral index image class
AIPS 1: IN3SEQ 0 Spectral index image sequence
AIPS 1: number
AIPS 1: IN3DISK 0 Spectral index image disk
AIPS 1: IN4NAME ' ' Spectral curvature name
AIPS 1: IN4CLASS ' ' Spectral curvature class
AIPS 1: IN4SEQ 0 Spectral curvature sequence
AIPS 1: number
AIPS 1: IN4DISK 0 Spectral curvature disk
AIPS 1: FQTOL -1 Frequency tolerance in kHz
AIPS 1: (primary beam & spec index)
AIPS 1: DOTV 1 Display residuals on TV ?
AIPS 1: Start with field = DOTV
AIPS 1: GRCHAN 0 Graphics channel of boundary
AIPS 1: BADDISK *all 0 Disks to avoid for scratch.
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