EVN User Experiment Pipeline Feedback


Pipeline feedback for experiment GM053. If you have any comments on this experiment please email the address below.
A detailed description of the pipeline output is available.

Last updated: Tue Nov 16 12:11:09 CET 2004 biggs@jive.nl

General Comments. ( Brief data summary and scan listing )
This is a Global VLBI imaging experiment at 18cm (dual polarisation, 4 IFs). Particpating EVN stations were Ef, Jb, Mc, Nt, Tr, Wb and On. The reference antenna for calibration and plotting was Ef. The EVN reliability indicator was ERI=0.97 (Jb=1.00, Wb=0.98, Ef=0.96, On=1.00, Mc=1.00, Tr=0.97, Nt=1.00). ERI gives you an estimate of the ratio of observed/good visibilities to the expected number. ERI* is the same, but excludes data lost due to circumstances out of the EVN's control e.g. bad weather (ERI*=0.97).

Plots of the autocorrelations .
Comments.
Probably rfi spikes are visible for many stations, most consistently possibly Mc (IF2). On IF1 shows extreme rfi for a large chunk of the experiment (18:00 - 20:30).

Plots of the uncalibrated amplitude and phase against time .
Comments.
Data look very nice. Bad data is obvious, most notably Wb after it has reached its hour angle limits and the Western VLBA antennas which are unable to see the source during the first part of the experiment. Note that the first two calibrator scans are much better than the last two. Gaps exist in the VLBA data due to bad playback.

Plots of the uncalibrated amplitude and phase against frequency channel .
Comments.
On rfi spike is visible in IF1 and has supressed amplitudes.

The uncalibrated amplitude and phase of the crosshand correlations against frequency channel (not available) .
Comments.

TSYS against time .
Comments.
On rfi is very obvious.

Telescope sensitivities from the a priori TSYS and Gain curves (the square of this number gives the antenna noise (SEFD) in Jy - the smaller the better).
Comments.
Do not trust the Nt gain correction curve. This is a known problem and should be fixed before full data reduction occurs. Otherwise, all antennas have the correct sensitivity according to the EVN Status Table. One exception is Tr where the gain factors are too high by a factor 2-3 i.e. telescope's sensitivity appears degraded.

Fringe-fit phase solutions (including Parallactic Angle correction).
Comments.
Phase connection looks very good. Ef variation is due to the parallactic angle correction.

Fringe-fit delay solutions .
Comments.
None.

Fringe-fit rate solutions .
Comments.
None.

Telescope bandpasses .
Comments.
None.

Calibrated amplitude and phase against time (a priori amplitude calibration and fringe-fit solutions applied).
Comments.
Most, but not all, of the bad data has been flagged during the fringe fitting.

Calibrated amplitude and phase against frequency channel .
Comments.
None.

Naturally weighted dirty map produced before self-cal of:
3C345: postscript , or FITS .
4C39.25: postscript , or FITS .
J0958+4725: postscript , or FITS .
J1221+4411: postscript , or FITS .
Comments.
None.

Uniformly weighted dirty map produced before self-cal of:
3C345: postscript , or FITS .
4C39.25: postscript , or FITS .
J0958+4725: postscript , or FITS .
J1221+4411: postscript , or FITS .
Comments.
None.

Phase corrections applied to a priori calibrated and fringe-fitted data by self-calibration.
3C345.
4C39.25.
J0958+4725.
J1221+4411.
Comments.
Note again that the last two calibrator scans need some additional flagging.

Amplitude corrections applied to a priori calibrated and fringe-fitted data by self-calibration.
3C345: postscript , or text file .
4C39.25: postscript , or text file .
J0958+4725: postscript , or text file .
J1221+4411: postscript , or text file .
Comments.
Tr and Nt corrections are large as expected. Removal of bad Nt gain curve is seen nicely for the phase reference source. A slightly worrying bimodality of the amplitude corrections are seen on the phase reference source, the EVN antennas showing a minority of solutions with lower amplitudes and the VLBA a minority with higher amplitudes. This is possibly due to bad data at the beginning of scans (no a priori flagging information is available for Wb).

Telescope sensitivities (the total AMP gain applied during both a priori and self calibration; the square of this number gives the antenna noise (SEFD) in Jy).
Comments.
Bimodal amplitude distribution very clear here.

Residual closure phase (visibility closure phase with model closure phase subtracted) for:
3C345 .
4C39.25 .
J0958+4725 .
J1221+4411 .
Comments.
None.

Calibrated visibilities and the source model of:
3C345 .
4C39.25 .
J0958+4725 .
J1221+4411 .
Comments.
Phase reference source shows the effect of the strange amplitude corrections, most clearly on the Ef-Wb baseline.

Calibrated visibilities against u,v distance for:
3C345. postscript , or png (smaller)
4C39.25. postscript , or png (smaller)
J0958+4725. postscript , or png (smaller)
J1221+4411. postscript , or png (smaller)
Comments.
Plenty of bad data still needs to be flagged.

u,v coverage for:
3C345. postscript , or png (smaller)
4C39.25. postscript , or png (smaller)
J0958+4725. postscript , or png (smaller)
J1221+4411. postscript , or png (smaller)
Comments.
None.

3C345: postscript , or FITS .
4C39.25: postscript , or FITS .
J0958+4725: postscript , or FITS .
J1221+4411: postscript , or FITS .
Comments.
Nice maps of all sources.