[daip] CPASS bug
Leonia Kogan
lkogan at aoc.nrao.edu
Tue Aug 6 15:18:35 EDT 2002
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>From spekkens at astro.cornell.edu Tue Aug 6 12:01 MDT 2002
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Date: Tue, 6 Aug 2002 14:00:40 -0400 (EDT)
From: Kristine Spekkens <spekkens at astro.cornell.edu>
To: Leonia Kogan <lkogan at zia.aoc.NRAO.EDU>
Subject: Re: [daip] CPASS bug
In-Reply-To: <200208061736.LAA20847 at bonito.aoc.NRAO.EDU>
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Status: RO
Hi Leonia,
The two central channels of the bandpass are corrupt because of the 1400
MHz birdie in the VLA (my galaxy is at an unfortunate redshift...). This
means that there is a lot of power on the shortest, North-South baselines
for those two channels only. It might be possible to salvage some useable
data from the channels, so I want to keep that option open during the
calibration. Since this is spectral line work, I want to be sure that
this corrupt data does not affect the bandpass solutions I derive, so I am
nervous about simply flagging the calibrator data that looks bad in those
channels and using BPASS. So my plan was to flag the calibrator data out
of those channels entirely, use CPASS to derive a BP table for all of the
channels (including the two central ones), and then to worry about
actually getting the power out of the source data once the calibration was
complete. Luckily, 1331+305 acts as both a flux and phase cal for the
observations, so I have a nice strong source from which to derive the
bandpass (which is why I figured CPASS might be the best option).
Is there a better way to tackle this?
A list of parameters used for CPASS follows. I actually tried a bunch of
different inputs for BPASSPRM and CPARM; below is the simplest setup I
could come up with in the end.
>inp
AIPS 1: CPASS Task to generate a polynomial 'Bandpass' (BP) table.
AIPS 1: Adverbs Values Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: USERID 0 User number
AIPS 1: INNAME '1331+305 ' Input UV file name (name)
AIPS 1: INCLASS 'CH3233' Input UV file name (class)
AIPS 1: INSEQ 1 Input UV file name (seq. #)
AIPS 1: INDISK 0 Input UV file disk unit #
AIPS 1:
AIPS 1: Data Selection
AIPS 1: CALSOUR '1331+305 ' 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: STOKES 'RR ' Stokes type 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: BCHAN 20 Lowest channel number 0=>all
AIPS 1: ECHAN 40 Highest channel 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: CMETHOD ' ' Modeling method:
AIPS 1: 'DFT','GRID',' '
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 (or SN) table to apply
AIPS 1: DOPOL -1 If >0 correct polarization.
AIPS 1: FLAGVER -1 Flag table version
AIPS 1: SOLINT 0 Solution interval (mins)
AIPS 1: -1 => do whole time range
AIPS 1: REFANT 14 Reference antenna
AIPS 1: BPVER 0 BP table version to write
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: BPASSPRM 0 2 Control information:
AIPS 1: 1 0 1: if > 0 use only the
AIPS 1: 1 10 autocorrelation data.
AIPS 1: 10 *rest 0 2: print level.
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 > 1 switch off the
AIPS 1: channel 0 divide option.
AIPS 1: 6: min. amp. closure err
AIPS 1: 7: min. ph. closure err
AIPS 1: 8: > 0 => scalar average
AIPS 1: 10: > 1 => normalize ampl.
AIPS 1: portion of bandpass by
AIPS 1: area under BP function.
AIPS 1: Useful for VLBI.
AIPS 1: 11: > 1, mode to allow
AIPS 1: calibration and divide
AIPS 1: by channel 0. Useful for
AIPS 1: VLBI. Do not use if you
AIPS 1: don't understand. See HELP
AIPS 1: CPARM 10 10 Fit parameters:
AIPS 1: 0.1 60 1: No. of terms.
AIPS 1: 2 0 2: Max. no. iterations.
AIPS 1: 0 1 3: Convergence tolerance.
AIPS 1: 0 0 4: Pre-average interval (sec)
AIPS 1: Default: Auto - 5 min.
AIPS 1: Cross - 15 min.
AIPS 1: 5: Fit type (1=Re/Im; 2=A/P)
AIPS 1: 6: BP table for initial val.
AIPS 1: 7: Fit phase only (1=> with
AIPS 1: ampl.; 2=> without)
AIPS 1: 8: >0 => Autoscale
AIPS 1: 9: >0 suppress data weighting
AIPS 1: ICHANSEL *all 0 Array of start and stop chan
AIPS 1: numbers, plus a channel
AIPS 1: 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: IN3CLASS ' ' Channel 0 uv name (class)
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
>
I hope that this helps!
Thanks,
Kristine
On Tue, 6 Aug 2002, Leonia Kogan wrote:
> Hi Kristine,
>
> >In particular, I am trying to calibrate the bandpass of a
> >dataset for which the two central channels are corrupt,
>
> If the same frequency channels are corrupted for all your data
> then you have to get rid of these channels (task AVSPC, UVFLG ...)...
>
> So tell me whether it is the case.
>
> Send me please the list of the input parameters you used for CBAND
>
> Leonia
>
>
>
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>
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