[daip] BPASS woes
Michael Rupen
mrupen at aoc.nrao.edu
Mon Mar 26 23:31:26 EST 2001
Dear DAIP,
yes, yet another lovely AIPS gripe from your friends in CV.
Consider if you will a typical VLA 21cm spectral line data set, taken
May 2000. 63 channels/IF, 4 IFs. One flux calibrator observed twice (3C286,
about 15 Jy). One phase/BP calibrator, 0.9 Jy, observed for 5mins every
40mins. One galaxy of interest observed all the rest of the time. Pretty
much vanilla otherwise, except that it's using the FIN (no change) option --
i.e. the calibrators were obs. at the identical freq. as the source.
So, off we merrily go to BPASS.
* BPASS with external CH.0 on the BP cal., then POSSM of the BP cal.
applying the BP table --> you get "horns" about 3% higher
than all the rest, just outside the inner 75% of the band.
* BPASS with *internally-calculated* CH.0 on the BP cal. gives the same
horns, if you use the inner 75%. If you use, say, ch. 30-40, you
get reasonable numbers (match the known flux) for ch. 30-40, and
much higher values for all other channels (about 10%). POSSM on the BP
table itself shows the expected "submarine" shape, 10% high in the
middle compared to the rest.
* TST (midnight job) gives the same answers as OLD (15OCT99).
The really weeeeird thing is that we only see this on the phase/BP cal. --
if you use 1331+305 everything is spiffy, except that it doesn't flatten
the edge channels (1-3 and 60-63), which are always *low* (rather than
just noisy).
In all cases - phase/BP cal & 1331+305, anyway you run 'em -- the phases
are lovely, all the way out to the band edge on both sides.
We've put a sample of the LINE data, an hour or so with just calibrators, from
UVCOP, in /home/mithril4/BPCRUD.UVFITS .
We append the inputs to BPASS (well, one run's worth anyhow) below.
Cheerio,
Michael & Lynn
inp bpass (in TST)
AIPS 1: BPASS Task to generate a "Bandpass" (BP) table.
AIPS 1: Adverbs Values Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: USERID 0 User number
AIPS 1: INNAME '20000526 ' Input UV file name (name)
AIPS 1: INCLASS 'UVCOP ' Input UV file name (class)
AIPS 1: INSEQ 1 Input UV file name (seq. #)
AIPS 1: INDISK 3 Input UV file disk unit #
AIPS 1:
AIPS 1: Data Selection
AIPS 1: CALSOUR '1221+282 ' Bandpass calibrator sources.
AIPS 1: *rest ' '
AIPS 1: QUAL -1 Calibrator qualifier -1=>all
AIPS 1: CALCODE ' ' Calibrator code ' '=>all
AIPS 1: UVRANG 0 0 UV range to select
AIPS 1: TIMERANG *all 0 Time range to select
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: BIF 0 Lowest IF number 0=>all
AIPS 1: EIF 0 Highest IF number 0=>all
AIPS 1: SUBARRAY 0 Subarray, 0=>all
AIPS 1: ANTENNAS *all 0 Antennas to select
AIPS 1:
AIPS 1: CLEAN map (optional)
AIPS 1: IN2NAME ' ' Cleaned map name (name)
AIPS 1: IN2CLASS ' ' Cleaned map name (class)
AIPS 1: IN2SEQ 0 Cleaned map name (seq. #)
AIPS 1: IN2DISK 0 Cleaned map disk unit #
AIPS 1: INVERS 0 CC file version #.
AIPS 1: NCOMP *all 0 # comps to use for model.
AIPS 1: 1 value per field
AIPS 1: FLUX 0 Lowest CC component used.
AIPS 1: NMAPS 0 No. Clean map files
AIPS 1: SMODEL *all 0 Source model, 1=flux,2=x,3=y
AIPS 1: See HELP SMODEL for details.
AIPS 1:
AIPS 1: Control options
AIPS 1: DOCALIB -1 If >0 calibrate data
AIPS 1: = 2 calibrate weights
AIPS 1: GAINUSE 2 CL table to apply (SN table
AIPS 1: to apply to single-source)
AIPS 1: DOPOL -1 If >0 correct polarization.
AIPS 1: FLAGVER 2 Flag table version
AIPS 1: SOLINT 0 Solution interval (mins)
AIPS 1: -1 => do whole time range
AIPS 1: REFANT 3 Reference antenna
AIPS 1: BPVER 0 BP table version to write
AIPS 1: 0 => a new table to be
AIPS 1: generated.
AIPS 1: SMOOTH *all 0 Smoothing function. See
AIPS 1: HELP SMOOTH for details.
AIPS 1: ANTWT *all 0 Ant. wts (0 => 1.)
AIPS 1: MINAMPER 10 Amplitude closure error
AIPS 1: regarded as excessive in %
AIPS 1: MINPHSER 5 Phase closure error regarded
AIPS 1: as excessive in degrees
AIPS 1: BPASSPRM *all 0 Control information:
AIPS 1: 1: if > 0 use only the
AIPS 1: autocorrelation data.
AIPS 1: 2: print level - see help
AIPS 1: 3: If > 0 do not divide data
AIPS 1: by source model
AIPS 1: 4: If > 0 store phases only
AIPS 1: in the BP table.
AIPS 1: 5: If <= 0 divide by 'channel
AIPS 1: 0' before determining BP.
AIPS 1: If > 0 switch off the
AIPS 1: channel 0 divide option.
AIPS 1: 6: amp closure error limit -
AIPS 1: print channels averaging
AIPS 1: over this if (2) > 0
AIPS 1: 7: phase closure error limit
AIPS 1: print channels averaging
AIPS 1: over this if (2) > 0
AIPS 1: 8: > 0 => scalar average
AIPS 1: 9: > 0 => interpolate over
AIPS 1: flagged channels if poss.
AIPS 1: 10: > 0 => normalize ampl.
AIPS 1: portion of bandpass by
AIPS 1: area under BP function.
AIPS 1: Useful for VLBI.
AIPS 1: 11: > 0 solution weights are
AIPS 1: independent of channel
AIPS 1: <=0, > -1.5 weights scaled
AIPS 1: by amplitude**2
AIPS 1: < -1.5 weights scaled by
AIPS 1: 1 / amplitude**2
AIPS 1: ICHANSEL 30 40 Array of start and stop chan
AIPS 1: 1 1 numbers, plus a channel
AIPS 1: *rest 0 increment and IF to be used
AIPS 1: to select channels to sum to
AIPS 1: find a 'channel 0'. If all
AIPS 1: 0, range set to inner 75% of
AIPS 1: observing band.
AIPS 1:
AIPS 1: 'Channel 0' uv-data
AIPS 1: IN3NAME ' ' Channel 0 uv name (name)
AIPS 1: must be '' to suppress option
AIPS 1: IN3CLASS ' ' Channel 0 uv name (class)
AIPS 1: must be '' to suppress option
AIPS 1: IN3SEQ 0 Channel 0 uv name (seq. #)
AIPS 1: IN3DISK 0 Channel 0 uv disk unit #
AIPS 1: BADDISK *all 0 Disks to avoid for scratch
inp POSSM: (gives a nice striking demo of the problem):
AIPS 1: POSSM Task to plot total and cross-power spectra.
AIPS 1: Adverbs Values Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: USERID 0 User number
AIPS 1: INNAME '20000526 ' Input UV file name (name)
AIPS 1: INCLASS 'UVCOP ' Input UV file name (class)
AIPS 1: INSEQ 1 Input UV file name (seq. #)
AIPS 1: INDISK 3 Input UV file disk unit #
AIPS 1: SOURCES '1221+282 ' 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: UVRANG 0 0 UV range to be plotted
AIPS 1: TIMERANG *all 0 Time range to be plotted
AIPS 1: STOKES ' ' Stokes type to select.
AIPS 1: BIF 1 Lowest IF number 0=>all
AIPS 1: EIF 1 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 *all 0 Antennas to select
AIPS 1: BASELINE *all 0 Baselines with ANTENNAS
AIPS 1: DOCALIB 1 If >0 calibrate data
AIPS 1: = 2 calibrate weights
AIPS 1: GAINUSE 2 CL (or SN) table to apply
AIPS 1: DOPOL -1 If >0 correct polarization.
AIPS 1: FLAGVER 2 Flag table version
AIPS 1: DOBAND 4 If >0 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: SHIFT 0 0 Position shift:
AIPS 1: RA, Dec (arcsec)
AIPS 1: 0 => no shift
AIPS 1: APARM *all 0 Control information:
AIPS 1: 1: = 0 => scalar average
AIPS 1: > 0 => vector average
AIPS 1: 2: = 0 => self-scale
AIPS 1: > 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: = 3 => plot ACF
AIPS 1: = 4 => plot XCF
AIPS 1: = 5 => plot cross power of
AIPS 1: individual antennas
AIPS 1: for cross polaris.
AIPS 1: (STOKES=RL, or LR)
AIPS 1: 9: > 0 => plot several IF's
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 ', 'AMP ', 'PHAS',
AIPS 1: 'R&I ', 'REAL', 'IMAG'
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 0 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 0 Number of plots per page
AIPS 1: BPARM *all 0 More control information:
AIPS 1: 1: If = 1 divide by 'channel
AIPS 1: 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: 5-9: 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: OUTFILE ' '
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 3 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: 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.
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