[daip] question about aips tasks
Hiroko Shinnaga
shinnaga at submm.caltech.edu
Mon Dec 20 18:19:43 EST 2004
Dear Eric Greisen,
Thank you very much for your kind and prompt
response to my questions.
> > 1. I found a disagreement between LISTR statements
> > and the plot made with VPLOT for a data set.
> > The situation is as follows. Although LISTR reports
> > data on some specific object were taken during some
> > specific time periods, the plot created by VPLOT is
> > shifted about 15 min from the LISTR statements. Namely,
> > the observing periods has a time lag roughly about 15
> > minutes between LISTR and VPLOT. I checked the observing
> > script which was run during the period. Comparing with
> > the script, it seems that LISTR output looks correct
> > and VPLOT looks not correct. With UVPLOT, the
> > plot of time vs. phase (or amp) agrees with
> > LISTR results. So, it seems VPLOT creates wrong plot.
> > I tried to specify time using the BPARM option. However,
> > the results were the same. Could you let me know
> > possible reasons why this is happening? Have you
> > seen this problem before?
>
> No and I do not see it when I try right now. I would need to
> see the inputs used to VPLOT. Note that time is BPARM(1)=12 in VPLOT
> and =11 in UVPLT. BPARM(1)=11 is Greenwich time but that should
> differ by an integer number of hours.
I set time as IAT hours for both UVPLT and VPLOT.
These should give us the same pattern for UVPLT and
VPLOT. But VPLOT gives me a weird pattern. I
carefully checked LISTR 'SCAN' output on the data.
I should get the pattern shown in UVPLT, not like
VPLOT. Here I attach the plots in gif.
>
> >
> > 2. Using the same data set, when I set xinc as 3
> > or 2 on vplot, I couldn't see almost any point on many
> > baselines (such as antenna 1, 8, 11, 17, 18,19,
> > etc). However, when I set xinc as 1, I could see
> > all the data points including baselines of antenna
> > 1 etc, which looked missing using xinc = 2 or 3.
> > Could you let me know possible reasons why this is
> > happening?
>
> If XINC=3 then only every 3rd point is considered for plotting.
> If the number of baselines selected with the adverbs is a multiple of
> 3 then you should see lots of points for some baselines and virtually
> none for others. Editing and other vagueries usually make XINC
> reasonable but in small data sets you could easily see the effect you
> are reporting. Use XINC=1, modern computers are fast enough.
Yes, I will use xinc=1, instead of 2 or 3, because
the computer is fast enough to handle it.
> >
> > 3. Above two issues are happening only on a specific
> > data set. I created this AIPS data file using
> > multiple(four) tape files with FILLM. For the
> > other data set that I created from one tape file
> > with FILLM, with the same options, I didn't have
> > the above problems. Do you think these are related?
> > (Please note that both data sets were taken using
> > fast switching. I don't know if these are related.
> > But just as a info. )
> >
> > I would like to appreciate your response soon,
> > if possible. I have my next VLA run this week
> > Thursday. In case the data itself have some problem,
> > I need to investigate my script to avoid these issues.
>
> Did you run FILLM 4 times and use DBCON or did you run FILLM once with
> all 4 files read? The latter may end up with times offset by 5 days.
> The former could get interesting too if the four files are from very
> different dates. Times are kept in single-precision floating days and
> would get inaccurate if many days were involved. But UVPLT and VPLOT
> should see the same times since the data are handed to both of them
> from the same subroutines.
>
The above might be caused by the way that I used FILLM.
Let me explain more about this. Followings are
the input parameters that I used to read the four
tape files.
///////////////////////////////////////
>inp
AIPS 1: FILLM Task to read a VLA archive tape
AIPS 1: Adverbs Values Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: INTAPE 1 Tape drive number
AIPS 1: INFILE 'MYAREA:AS813.NOV02.XP '
AIPS 1: Non-blank: disk file name
AIPS 1: NFILES 0 Number of files to advance
AIPS 1: Also applies to ON-LINE!
AIPS 1: BAND ' ' Freq. band (4,P,L,C,X,U,K,Q)
AIPS 1: QUAL -1 Source qualifier -1=>all
AIPS 1: CALCODE ' ' Calibrator code
AIPS 1: VLAOBS ' ' VLA obs. pgm. name ('AZ99')
AIPS 1: VLAMODE ' ' VLA obs. mode (' '=any)
AIPS 1: REFDATE ' ' Reference date. 'yyyymmdd'
AIPS 1: TIMERANG *all 0 Timerange selected
AIPS 1: BCHAN 1 First spectral channel
AIPS 1: ECHAN 0 Highest spectral channel
AIPS 1: OUTNAME ' ' Output UV file name (name)
AIPS 1: OUTSEQ 0 Output UV file name (seq. #)
AIPS 1: OUTDISK 1 Output UV file disk unit #.
AIPS 1: DOUVCOMP -1 1 (T) => compressed data
AIPS 1: DOALL -1 1 (T) => write all data.
AIPS 1: DOCONCAT -1 1 (T) => append data to old
AIPS 1: files
AIPS 1: NCOUNT 0 Number of files to read
AIPS 1: DOWEIGHT 1 Use nominal sensitivity to
AIPS 1: scale weights?
AIPS 1: = 10, use Memo 108 weights
AIPS 1: DOACOR -1 Load autocorrelation data?
AIPS 1: CPARM 0 0 User options.
AIPS 1: 0 0 1 => Avg. time (seconds)
AIPS 1: 0 0 2 => bitmap (see help)
AIPS 1: 0 0.05 = 16 for planets & Sun
AIPS 1: 0 0 3 => Max. OK IF status
AIPS 1: <=3 => 3
AIPS 1: 4 => Control dropping of
AIPS 1: ** press RETURN for more, enter Q or next line to quit print **
#
AIPS 1: shadowed data
AIPS 1: < 0 => no shadow check
AIPS 1: 0 => 25 m limit
AIPS 1: > 0 => Shadow limit is
AIPS 1: CPARM(4) in meters
AIPS 1: 5 = channel code (see HELP)
AIPS 1: 6 => Subarray number-see HELP
AIPS 1: 7 => FQ entry tolerance (kHz)
AIPS 1: (see HELP)
AIPS 1: 8 => CL table time incr. min
AIPS 1: 9 => TY table time incr. min
AIPS 1: 10=> Calibrator avg. time
AIPS 1: DPARM *all 0 Selection by Frequency
AIPS 1: 1+2 => A Frequency (Hz)
AIPS 1: 3+4 => B Frequency (Hz)
AIPS 1: 5+6 => C Frequency (Hz)
AIPS 1: 7+8 => D Frequency (Hz)
AIPS 1: 9 => tolerance for A&C
AIPS 1: 10 => tolerance for B&D
AIPS 1: BPARM 20 1 Opacity and Gain curve
AIPS 1: 0 0 control (see help)
AIPS 1: 0 0 0 0
AIPS 1: 0 0.75
AIPS 1: IN2FILE ' '
AIPS 1: Antenna gains file
/////////////////////////////////////////////////////////////
Under the directory MYAREA, I have four tape
files named as follows.
AS813.NOV02.XP1
AS813.NOV02.XP2
AS813.NOV02.XP3
AS813.NOV02.XP4
I issued "go" only once to use FILLM.
I was told that the above parameter setting
for infile 'MYAREA:AS813.NOV02.XP" would
work. Would you think this is not a right
way to do?
> So far as I can tell you should have no problem in your data, but I
> have no idea what VPLOT appears to be doing or why.
I really hope that would be the case.
Hope to hear from you. Thank you very much for
your help.
Hiroko
--
Hiroko Shinnaga, Staff Scientist email: shinnaga at submm.calteh.edu
Caltech Submillimeter Observatory Phone: 808-935-1909
California Institute of Technology Fax: 808-961-6273
111 Nowelo St., Hilo, HI 96720 USA http://puuoo.submm.caltech.edu/~hs
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