[daip] Smoothing in POSSM.
R. Craig Walker
cwalker at nrao.edu
Tue Mar 12 22:37:14 EDT 2013
When I try using POSSM on a wideband VLBA data set (8 IF, 32 MHz each full
pol with 64 spectral channels per IF), if I use SMOOTH and restrict the
channel range (9-56), I get droopy ends to the phases. The ends droop for
several channels on each end of every IF. All go in the same direction on
a given baseline, but can go the other direction on another baseline. If
I open up to all channels, I don't see the effect. If I don't smooth, I
don't see any justification in the unsmoothed data for such droops. It
happens for both gaussian and box smoothing and for both before and after
bandpass calibration. In fact, the effect shows up when bandpass is not
applied.
See the attached plots. The first shows the effect in a smoothed, channel
restricted case. The second shows the full band smoothed and the third
shows the full band unsmoothed.
Below are my possm inputs followed by an image header. The reference
antenna in all tasks that need one is LA.
The droops seem to be some artifact of the smoothing. Is there a reason
that this behavior is expected, or is there some issue with POSSM?
Cheers
Craig
Inputs:
>inp possm
AIPS 1: POSSM Task to plot total and cross-power spectra.
AIPS 1: Adverbs Values Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: USERID 0 User number - ignored
AIPS 1: INNAME 'BW098A_43' Input UV file name (name)
AIPS 1: INCLASS 'MULTI' Input UV file name (class)
AIPS 1: INSEQ 1 Input UV file name (seq. #)
AIPS 1: INDISK 5 Input UV file disk unit #
AIPS 1: SOURCES 'OJ287' Source list
AIPS 1: *rest ' '
AIPS 1: QUAL -1 Source qualifier -1=>all
AIPS 1: CALCODE ' ' Calibrator code ' '=>all
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: UVRANGE 0 0 UV range to be plotted
AIPS 1: TIMERANG 0 8 Time range to be plotted
AIPS 1: 6 15 0 8
AIPS 1: 6 45
AIPS 1: STOKES 'RR' Stokes type(s) to select.
AIPS 1: BIF 1 Lowest IF number 0=>all
AIPS 1: EIF 8 Highest IF number 0=>all
AIPS 1: BCHAN 1 Lowest channel number 0=>all
AIPS 1: ECHAN 0 Highest channel number 0=>all
AIPS 1: SUBARRAY 0 Subarray, 0=>1
AIPS 1: ANTENNAS 5 *rest 0 Antennas to select
AIPS 1: BASELINE 1 2 Baselines with ANTENNAS
AIPS 1: *rest 0
AIPS 1: DOCALIB 2 > 0 calibrate data & weights
AIPS 1: > 99 do NOT calibrate weights
AIPS 1: GAINUSE 14 CL (or SN) table to apply
AIPS 1: DOPOL -1 If >0 correct polarization.
AIPS 1: PDVER 0 PD table to apply (DOPOL>0)
AIPS 1: BLVER -1 BL table to apply.
AIPS 1: FLAGVER 4 Flag table version
AIPS 1: DOBAND 2 If >0 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 7 6 Smoothing function. SEE
AIPS 1: 6 POSSM HELP SPECIAL VALUES
AIPS 1: SHIFT 0 0 Position shift:
AIPS 1: RA, Dec (arcsec)
AIPS 1: 0 => no shift
AIPS 1: APARM 0 0 Control information:
AIPS 1: 0 0 1: < 0 => scalar average
AIPS 1: 0 0 >= 0 => vector average
AIPS 1: 0 0 2: = 0 => self-scale
AIPS 1: 1 0 > 0 => fixed scale
AIPS 1: (use APARM(3-6))
AIPS 1: 3: min. amplitude
AIPS 1: 4: max. amplitude
AIPS 1: 5: min. phase (degrees)
AIPS 1: 6: max. phase
AIPS 1: 7: x-axis labelling
AIPS 1: = 0 = > in channels.
AIPS 1: = 1 = > in Hz (or secs
AIPS 1: if corr. fn)
AIPS 1: = 2 = > in m/s
AIPS 1: 8: = 0 => plot cross power
AIPS 1: = 1 => plot total power
AIPS 1: = 2 => plot BP table
AIPS 1: version BPVER
AIPS 1: = 3 => plot ACF
AIPS 1: = 4 => plot XCF
AIPS 1: = 5 => plot BD table
AIPS 1: version BPVER
AIPS 1: = 6 => plot PD table
AIPS 1: version BPVER
AIPS 1: = 7 => plot CP table
AIPS 1: version BPVER
AIPS 1: = 8 => plot CP table / I
AIPS 1: version BPVER
AIPS 1: 9: > 0 => plot several IF's
AIPS 1: and/or polarizations
AIPS 1: together as though one
AIPS 1: long spectrum (see HELP)
AIPS 1: 10: > 0 => reverse direction
AIPS 1: of plotted spectrum, so
AIPS 1: velocity increases to
AIPS 1: right.
AIPS 1: CODETYPE 'A&P' 'A&P ', 'AMP ', 'PHAS',
AIPS 1: 'R&I ', 'REAL', 'IMAG'
AIPS 1: 'LA&P', 'LAMP'
AIPS 1: other => 'A&P '
AIPS 1: POLPLOT ' ' Option to display various
AIPS 1: combinations of polzns to
AIPS 1: plot: 'RL/RR', 'RL/LL',
AIPS 1: 'LR/RR', 'LR/LL', 'RR/LL'
AIPS 1: 'LL/RR'; other = don't use
AIPS 1: this option.
AIPS 1: SOLINT 1 If SOLINT > 0 then it enables
AIPS 1: the user to make multiple
AIPS 1: plots per pass of POSSM.
AIPS 1: It defines the averaging time
AIPS 1: for each individual plot.
AIPS 1: Task will start at TIMERANG
AIPS 1: and make a plot for every
AIPS 1: SOLINT minutes. If SOLINT
AIPS 1: = -1 will do the same but
AIPS 1: will do scan averages if NX
AIPS 1: table is present.
AIPS 1: NPLOTS 2 Number of plots per page
AIPS 1: BPARM 1 0.01667 More control information:
AIPS 1: 0.01667 0.01667 1: If = 1 divide by 'channel
AIPS 1: 0.01667 *rest 0 0' before plotting data.
AIPS 1: 0 => do not divide.
AIPS 1: 2: Start chn. of 'channel 0'
AIPS 1: (0 => determined by POSSM)
AIPS 1: 3: Stop chn. of 'channel 0'
AIPS 1: (0 => determined by POSSM)
AIPS 1: 4: ignore spectrum when ampl.
AIPS 1: channel 0 < BPARM(4) Jy
AIPS 1: 5: scale LOG10 plots by B(5)
AIPS 1: 6-9: unused
AIPS 1: 10: =1 => don't write header
AIPS 1: info when writing to outfile
AIPS 1: useful for appending several
AIPS 1: spectra into a single outfile
AIPS 1: [see EXPLAIN POSSM]
AIPS 1: OUTTEXT ' '
AIPS 1: Filename in which to write
AIPS 1: spectrum. Default = ' ' =
AIPS 1: do not write spectrum. The
AIPS 1: file is written only if
AIPS 1: NPLOTS = 0
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: FACTOR 0 Scale plus signs by FACTOR
AIPS 1: XYRATIO 0 XY plot ratio: 0 -> 1.636
AIPS 1: BADDISK *all 0 Disks to avoid for scratch
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.
Image header:
>imh
AIPS 1: Image=MULTI (UV) Filename=BW098A_43 .MULTI . 1
AIPS 1: Telescope=VLBA Receiver=VLBA
AIPS 1: Observer=BW098A User #= 604
AIPS 1: Observ. date=12-JAN-2013 Map date=11-FEB-2013
AIPS 1: # visibilities 561591 Sort order TB
AIPS 1: Rand axes: UU-L-SIN VV-L-SIN WW-L-SIN TIME1 BASELINE
AIPS 1: SOURCE FREQSEL INTTIM GATEID CORR-ID WEIGHT
AIPS 1: SCALE
AIPS 1: ----------------------------------------------------------------
AIPS 1: Type Pixels Coord value at Pixel Coord incr Rotat
AIPS 1: COMPLEX 1 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: STOKES 4 -1.0000000E+00 1.00 -1.0000000E+00 0.00
AIPS 1: FREQ 64 4.3024000E+10 0.75 5.0000000E+05 0.00
AIPS 1: IF 8 1.0000000E+00 1.00 1.0000000E+00 0.00
AIPS 1: RA 1 00 00 00.000 1.00 0.000000 0.00
AIPS 1: DEC 1 00 00 00.000 1.00 0.000000 0.00
AIPS 1: ----------------------------------------------------------------
AIPS 1: Coordinate equinox 2000.00
AIPS 1: Maximum version number of extension files of type HI is 1
AIPS 1: Maximum version number of extension files of type SN is 10
AIPS 1: Maximum version number of extension files of type AT is 1
AIPS 1: Maximum version number of extension files of type NX is 1
AIPS 1: Maximum version number of extension files of type IM is 1
AIPS 1: Maximum version number of extension files of type CT is 1
AIPS 1: Maximum version number of extension files of type MC is 1
AIPS 1: Maximum version number of extension files of type PL is 14
AIPS 1: Maximum version number of extension files of type BP is 2
AIPS 1: Maximum version number of extension files of type CL is 18
AIPS 1: Maximum version number of extension files of type GC is 3
AIPS 1: Maximum version number of extension files of type WX is 1
AIPS 1: Maximum version number of extension files of type TY is 2
AIPS 1: Maximum version number of extension files of type PC is 1
AIPS 1: Maximum version number of extension files of type FQ is 1
AIPS 1: Maximum version number of extension files of type AN is 1
AIPS 1: Maximum version number of extension files of type SU is 1
AIPS 1: Maximum version number of extension files of type CQ is 1
AIPS 1: Maximum version number of extension files of type FG is 4
AIPS 1: Keyword = 'OLDRFQ ' value = 4.30560000D+10
AIPS 1: Keyword = 'MAXABSU ' value = -1.000000E+00
---------------------------------------------------------------------
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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