[daip] WSRT/AIPS
Amy Mioduszewski
amiodusz at nrao.edu
Tue Feb 10 19:37:41 EST 2009
Dear Shea,
Unfortunately, Eric is on vacation for the next couple weeks.
I looked at the images you sent and it is very strange the distortion you see is
a shift towards the north in the WRST image that gets bigger as you get further
from the phase center. I have a few questions/suggestions so we can figure out
if this is an IMAGR or a WSRT problem:
1) What version of AIPS are you running and can you run a different version of
IMAGR on the data.
2) Try UVFIX on the data before imaging (this recalculates the u,v,w)
3) Image a small field around one of the sources far from the phase center and
see if the position shift is the same as in the big image. Use DO3DIMAG=1 so
the tangent point is moved to the center of the field.
Amy
Shea D. Brown wrote:
> Hello Eric (or others),
> Larry and I have run into a very strange problem when making images of
> WSRT data with IMAGR. It seems that the WSRT images are distorted in a
> strange way (it does NOT look like the frequency is wrong). I've included
> a WSRT image made with IMAGR (the inputs are below), and the same field
> from skyview NVSS and the WENSS survey (made with WSRT). NVSS and WENSS
> agree, but the WSRT image does not? If you have any ideas as to what is
> going on, that would be most helpful. Thanks, and I hope all is going
> well.
>
> Shea Brown
> Department of Astronomy
> University of Minnesota
>
> AIPS 1: IMAGR: Wide field imaging/Clean task
> AIPS 1: Adverbs Values Comments
> AIPS 1: ----------------------------------------------------------------
> AIPS 1: INNAME 'IF8CH114' Input UV data (name)
> AIPS 1: INCLASS 'UV' Input UV data (class)
> AIPS 1: INSEQ 5 Input UV data (seq. #)
> AIPS 1: INDISK 7 Input UV data disk drive #
> AIPS 1: SOURCES 'COMA_SE' Source name
> AIPS 1: *rest ' '
> 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 2 CL (or SN) table to apply
> AIPS 1: ** press RETURN for more, enter Q or next line to quit print **
> #
> AIPS 1: DOPOL 1 If >0.5 correct polarization.
> AIPS 1: BLVER -1 BL table to apply.
> AIPS 1: FLAGVER 1 Flag table version
> AIPS 1: DOBAND -1 If >0.5 apply bandpass cal.
> AIPS 1: Method used depends on value
> AIPS 1: of DOBAND (see HELP file).
> AIPS 1: BPVER -1 Bandpass table version
> AIPS 1: SMOOTH *all 0 Smoothing function. See
> AIPS 1: HELP SMOOTH for details.
> AIPS 1: STOKES 'V' Stokes parameters (see HELP)
> AIPS 1: BCHAN 0 Low freq. channel 0 for cont.
> AIPS 1: ECHAN 0 Highest freq channel
> AIPS 1: CHANNEL 0 Restart channel number
> AIPS 1: NCHAV 1 Number of chan. to average.
> AIPS 1: CHINC 1 Channel incr. between maps.
> AIPS 1: BIF 0 First IF in average.
> AIPS 1: EIF 0 Last IF in average.
> AIPS 1: OUTNAME ' ' Output image name (name)
> AIPS 1: OUTDISK 7 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 15 15 (X,Y) size of grid in asec
> AIPS 1: IMSIZE 1024 1024 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: ** press RETURN for more, enter Q or next line to quit print **
> #
> 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 0 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 10000 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 0 Number of boxes for Clean
> AIPS 1: NB: field 1 only.
> AIPS 1: CLBOX *all 0 Four coordinates for each box
> 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: ** press RETURN for more, enter Q or next line to quit print **
> #
> AIPS 1: OBOXFILE *all ' ' Output file for final Clean
> AIPS 1: boxes
> AIPS 1: GAIN 0.05 Clean loop gain
> AIPS 1: FLUX 0 Minimum Clean component (Jy)
> AIPS 1: MINPATCH 51 Min. BEAM half-width in AP.
> AIPS 1: BMAJ 60 FWHM(asec) major axis Clean
> AIPS 1: restoring beam.
> AIPS 1: BMIN 60 FWHM(asec) minor axis Clean
> AIPS 1: restoring beam.
> AIPS 1: BPA 0 Clean beam position angle
> AIPS 1: OVERLAP 0 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: ** press RETURN for more, enter Q or next line to quit print **
> #
> 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 30000 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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