[daip] FITLD problems
Eric Greisen
egreisen at nrao.edu
Wed Feb 23 10:40:14 EST 2011
李俊铎 wrote:
> Dear sir or madam,
>
> We got the data from WSRT in UVFIT format, but some of the files are
> unable to load in AIPS with FITLD correctly.
>
> Error messages are as follows (pictures get from screen), there are two
> kinds of errors.
> /**/
> FITRXU
> In this condition, the data are actually there and has a header we can
> read, but we have no idea whether the data has been loaded correctly.
>
>
> UVFDAT
> In this condition, the data are not loaded, we cannot find it with UCAT.
>
> My OS is Fedora 13. AIPS version is 31DEC10/*.*/
>
> The parameter values that we have set is as follow:
>
> AIPS 1: FITLD: Task to store an image or UV data from a FITS tape
> AIPS 1: Adverbs Values Comments
> AIPS 1: ----------------------------------------------------------------
> AIPS 1: INTAPE 1 Input tape drive # (0 => 1)
> AIPS 1: NFILES 0 # of files to advance on tape
> AIPS 1: DATAIN 'FITS:11002869_S0_T0_FM Disk file name
> AIPS 1: 0.UVF'
> AIPS 1: OUTNAME 'X0' File name (name)
> AIPS 1: OUTCLASS ' ' File name (class)
> AIPS 1: OUTSEQ 0 File name (seq. #)
> AIPS 1: 0 => highest unique number
> AIPS 1: => matching (on VLBA)
> AIPS 1: -1 => FITS tape value
> AIPS 1: OUTDISK 0 Disk drive # (0 => any)
> AIPS 1: OPTYPE ' ' Type of data to load,
> AIPS 1: ' ' => all types
> AIPS 1: 'UV' => UV data
> AIPS 1: 'IM' => images
> AIPS 1: NCOUNT 0 Number of files to load.
> AIPS 1: DOTABLE 1 True (1.0) means load tables
> AIPS 1: for images.
> AIPS 1: DOUVCOMP 1 >0 => compressed data (FITS)
> AIPS 1: DOCONCAT -1 >0 -> if VLBA correlator data
> AIPS 1: append data to existing
> AIPS 1: files, or if no appropriate
> AIPS 1: files exist create a new file
> AIPS 1: and append all data to that
> AIPS 1: file.
> AIPS 1: *****************************
> AIPS 1: Following adverbs are useful
> AIPS 1: only when reading VLBA
> AIPS 1: distribution tapes.
> AIPS 1: *****************************
> AIPS 1: CLINT 0 CL entry interval (min)
> AIPS 1: 0 => 1 minute.
> AIPS 1: SOURCES *all ' ' Source list to accept.
> AIPS 1: QUAL -1 Source qualifier -1=>all
> AIPS 1: TIMERANG *all 0 Timerange selected
> AIPS 1: BCHAN 1 Lowest spectral channel
> AIPS 1: number to select in each IF.
> AIPS 1: 0=>1
> AIPS 1: ECHAN 0 Highest spectral channel
> AIPS 1: number to select in each IF.
> AIPS 1: 0=>highest
> AIPS 1: BIF 1 Lowest IF number 0=>1
> AIPS 1: EIF 1 Highest IF number 0=>all
> AIPS 1: DIGICOR 1 Controls the application of
> AIPS 1: the VLBA correlator's digital
> AIPS 1: correction.
> AIPS 1: 0 or 1 => perform corrections
> AIPS 1: 2 => perform cross-power
> AIPS 1: corrections, do total-power
> AIPS 1: only if zero padding used.
> AIPS 1: -1 => do NOT perform
> AIPS 1: corrections.
> AIPS 1: SEE HELP for more details
> AIPS 1: SELBAND -1 Bandwidth to select (kHz)
> AIPS 1: SELFREQ -1 Frequency to select (MHz).
> AIPS 1: See HELP.
> AIPS 1: FQTOL -1 Frequency tolerance assigned
> AIPS 1: to SELFREQ, FITLD will select
> AIPS 1: data with freq. of SELFREQ
> AIPS 1: +/- FQTOL.
> AIPS 1: The unit of FQTOL is kHz.
> AIPS 1: <=0 => 10 kHz
> AIPS 1: WTTHRESH 0 Flagging threshold based on
> AIPS 1: weights. See HELP.
> AIPS 1: 0 => no flagging
> AIPS 1: 1 => will flag ALL data
> AIPS 1: OPCODE ' ' Specify if wish to keep VT
> AIPS 1: (VLBA Tape Statistics) table
> AIPS 1: and other tables. See HELP.
> AIPS 1: ' ' => do not save tables
> AIPS 1: NPIECE 0 Maximum uv table piece to
> AIPS 1: load (ignored for tape unless
> AIPS 1: NCOUNT = 1)
> AIPS 1: ERROR 2 >= 2 -> do not use AIPS
> AIPS 1: history in the FITS file
> AIPS 1: ANTNAME *all ' ' List antenna station names in
> AIPS 1: desired order (IDI data only)
>
>
> We do not understand what in the cause of an error. We try to read them
> in different versions of AIPS and try to load them with other task like
> UVLOD, but it does not make a different.
>
> Could you help on this? Does it indicate that the files were corrupted?
>
Unfortunately - yes. The files have a premature end of file. I suspect
that you could do an ls -l on the files and will find their length is
not an integer times 2880. Given that there are not lots of other error
messages, I suspect that the cause is simply a premature end of the ftp
copying. It is possible that the ftp was not in binary mode and so
could corrupt the file itself, but I would expect that to lead to other
error messages ahead of the error 4. The worst possibility of course is
that the FITS writing program of the WSRT does not obey the FITS
standard and actually writes files that are not an integer number of the
fundamental 2880 byte record size. That also seems unlikely.
FITRXU is in the stage of reading binary tables such as the antenna (AN)
and frequency (FQ) tables. Without these the data are not likely to be
of use although maybe you could make progress. UVFDAT is the routine
that reads the UV data themselves and so, in that case, the end of file
came so early that the UV data themselves are foreshortened. In that
case, FITLD deletes the output file. Try transmitting these files from
the WSRT again (if I am right about the length issue) and try to check
their length at the source as well as on your disk after the copying.
Eric Greisen
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