EVN User Experiment Pipeline Feedback
Pipeline feedback for experiment GV016_1.
If you have any comments on this experiment please email
the
address below.
Last updated: Tue Apr 15 14:06:16 CEST 2003
imai@jive.nl
|
General Comments.
(
Brief data summary and
scan listing.)
This project consists of 14 telescopes: Eb, Cm, Mc, Wb, Gb, Y27 and 8 VLBA telescopes. Jb, Tr, Hn and Kp did not observe.
There are three passes, 1st for 1720-MHz OH line (IF2 R&Lpols), 2nd for 1665/1667-MHz OH lines (IF1 Lpol) and 3rd for 1665/1667-MHz OH lines (IF1 Rpol). This page is for the 1st pass.
The 1st pass consists of 12 telescopes available. Used 8-MHz 1 bands x 2 pols, with 2-bits sampling. Obtained 2 pairs of polarization (LL, RR) in 4-sec integration. 256 spectral channels per IF.
Gb is a reference antenna.
ERI=0.28 (Eb=1.00, Mc=0.90, Wb=1.00, Jb=0.00, Tr=0.00). ERI*=0.28 (artificial errors only). Global VLBI reliable index~0.68.
Plots of the autocorrelations.
Comments.
Eb: Ripples in Rpol.
Mc: RFIs around the band center in R&Lpols.
Wb: Sometimes spur in Rpol.
Gb: Sometimes spurs in R&Lpols.
Sc, La, Pt: Occasionally RFIs in R&Lpols.
Br, Mk: Sometimes weak spurs in R&Lpols.
Plots of the uncalibrated amplitude and phase against time.
Comments.
Calibrators were detected with large phase drifts.
Mc: No fringe during 16:30-18:00.
Fd: Phase wrap 02:40-03:40.
Mk: Phase wrap.
Plots of the uncalibrated amplitude and phase against frequency
channel.
Comments.
Calibrators were well detected in each of scans with phase gradients along frequency.
Mc: RFIs in RR&LL 16:32-18:04.
Ov, Br, Mk: Occasionally phase wrap.
La: RFIs in RR&LL.
The uncalibrated amplitude and phase of the crosshand
correlations against frequency channel.
Comments.
No data.
TSYS against time.
Comments.
Cm: Sparse data points. Tsys values not available, set to Tsys=1 K.
Jb: Sparse data points.
Mc: High Tsys aorund 02:30.
Gb: High Tsys 00:40, 02:30-03:40, 09:50-10:20.
La: Data wrap 23:30-07:00.
Mk: Hight Tsys 23:30-03:00.
Yy: Ta/Tsys value input.
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.
Eb: About 200% of that in EVN status table.
Mc: About 150% of that in EVN status table.
Wb: About 140% of that in EVN status table.
Gb: SEFD~50 Jy and 12 Jy in Rpol and Lpol, respectively.
VLBA tels: SEFD=200-300 Jy.
Fringe-fit phase solutions.
Comments.
Gb (reference): Phase slope due to parallactic angle correction.
Mc: Solutions lost 15:30-16;30 in RR&LL.
Fringe-fit delay solutions.
Comments.
Eb, Mc: Offsets systematically varied from -20 nsec to 0 nsec.
Wb: Offsets systematically varied from -40 nsec to -10 nsec.
Sc, Nl: Offsets within 10 nsec.
Other VLBA tels: Offsets systematically within 200 nsec.
Fringe-fit rate solutions.
Comments.
Rate offsets within 5 mHz.
Mc: Large rate offsets 16:30-18:00.
Mk: Rate offsets up to 10 mHz 23:30-03:30.
Telescope bandpasses.
Comments.
Bandpass amplitudes and phases were well determined.
Calibrated amplitude and phase against time
(a priori amplitude calibration and fringe-fit solutions applied).
Comments.
Large phase drifts were reduced. Occasionally large phase offsets and wrap still remain.
Mc: No fringe 16:30-18:00.
Calibrated amplitude and phase against frequency channel.
Comments.
Phase gradients along frequency were removed.
Wb, Br, Mk: Occasionally phase offsets.
La, Sc: Occasionally phase offsets due to RFIs.
Phase corrections applied to a priori calibrated and fringe-fitted data by self-calibration.
Comments.
Phase solutions determind in each scan of the calibrators.
Naturally weighted dirty map produced before self-cal of:
3C454.3.
3C84.
DA193.
Comments.
3C454.3: Only fringe pattern above 2nd contour (3.0 Jy/beam) due to poor u-v coverage.
3C84: Marginally detected above 3rd contour (7.0 Jy/beam).
DA193: Only fringe pattern above ??? contour (??? Jy/beam) due to poor u-v coverage.
Uniformly weighted dirty map produced before self-cal of:
3C454.3.
3C84.
DA193.
Comments.
3C454.3: Marginally detected above 2nd contour (1.9 Jy/beam).
3C84: Appears over 3rd contour (3.6 Jy/beam).
DA193: Marginally detected above 2nd contour (0.49 Jy/beam).
Amplitude corrections applied to a priori calibrated and fringe-fitted data by self-calibration.
Also available as a text file.
Comments.
Gain correction factors usually within 2.0.
Sc: Too large gain correction factor at 10:15.
Mk: Occasionally gain correction factors up to 3.0.
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.
Eb: About 140% of that in EVN status table.
Mc: Difficult to evaluate sensitivity due to too high gain values contaminating. Roughly consistent with that in EVN status table.
Wb: Roughly consistent with that in EVN status table.
Gb: Difficult to evaluate sensitivity due to too high gain values contaminating. SEFD~10 Jy.
VLBA tels: SEFD=200-400 Jy.
Residual closure phase (visibility closure phase with model closure phase subtracted) for:
3C454.3.
3C84.
DA193.
Comments.
3C454.3, DA193: Systematic closure phase variation was seen within 20 degrees.
3C84: Systematic closure phase variation was seen up to 100 degrees. Occasionally closure phase wrap.
Calibrated visibilities and the source model of:
3C454.3.
3C84.
DA193.
Comments.
3C454.3; The source model is consistent with the observed amplitudes and phase, except for those in Mc 00:30.
3C84: Occasionally the source model is inconsistent with both the observed amplitudes and phase in VLBA telescopes.
DA193: Occasionally the source model is inconsistent with the observed amplitudes.
Calibrated visibilities against u,v distance for:
3C454.3. postscript , png (smaller)
3C84. postscript , png (smaller)
DA193. postscript , png (smaller)
Comments.
3C454.3: About 14 Jy at 0M lambda and about 2 Jy at 62M lambda.
3C84: About 22 Jy at 0M lambda and <1 Jy at 60M lambda.
DA193: 2.2 Jy at 0M lambda and 1.8 Jy at 46M lambda.
u,v coverage for:
3C454.3
postscript, png (smaller)
3C84
postscript, png (smaller)
DA193
postscript, png (smaller)
Comments.
3C454.3, 3C84: Elongated in east-west direcition up to 60M lambda.
DA193: Elongeated in north-south direction up to 30M lambda, plus clusters of data points in the east and west direction at 40M lambda.
Crude map of 3C454.3 from the pipeline.
Crude map of 3C84 from the pipeline.
Crude map of DA193 from the pipeline.
Comments.
3C454.3: A couple of components.
3C84: A core elongated structure in the north-south direction.
DA193: An unresolved core and bright side lobes.