EVN Network Monitoring Experiment (NME) Pipeline Feedback
Pipeline feedback for NME N02X1.
If you have any comments on this experiment please email
the
address below.
Last updated: Mon Apr 29 16:51:41 CEST 2002
reynolds@jive.nl
|
General Comments.
Single polarization experiment (RCP) using two heads recording (512 Mbit/s data rate, 128 MHz bandwidth). Effelsberg is the reference antenna. Two sources observed in phase-referencing mode (DA 193-reference; J0605+4030-target). Westerbork stuck on the target source after the second scan. Effelsberg did not observe at the beginning of the experiment because of strong winds. There were problems with the antenna control in Yebes, much of the data is lost.
Plots of the autocorrelations.
Comments.
Ef: R16 (IF 16 in AIPS) is dead because of a dead track
Mc: R6 has low amplitude; some RFI in R7 and R9
Wb: recorded only the first headstack (R1-8) due to limited bandwidth
Ur: low amplitude in R4 and R11
Yb: problems with R13, maybe RFI
Plots of the uncalibrated amplitude and phase against time.
Comments.
No useful data in R5 and R13 on Ef-Mc and Mc-On baselines; this is due to a correlator hardware fault, currently being investigated. R5 and R13 are corresponding bands from correlation of the first and second head.
Ef: could not observe in the first 40 minutes
Wb: stuck on target after second scan; problems with phasing up the array? did not observe in the second headstack due to restricted bandwidth
Yb: no data for two hours in the middle of the experiment
Ur: fringe rate is high, but phases look good
Sh: fringe rate is high, but phases look good - except in R11 and R12 (BBC 6 upper and lower sideband)
Plots of the uncalibrated amplitude and phase against frequency
channel.
Comments.
R5 and R13 on Ef-Mc and Mc-On baselines: see above.
Ef: amplitude is low in R15
Wb: very low amplitude outside of the central 4 MHz in each IF; no data on second headstack (see above)
Sh: R11 and R12 looks bad (BBC 6 upper and lower sideband)
Ur: low amplitude in R4 (BBC 3 upper sideband) and R11 (BBC 11 upper sideband), also seen in autocorrelations
Mc: some RFI leaks through even crosspolarization spectrum (R5, R7, R9)
Yb: RFI leaks through crosspolarization spectrum in R13
The uncalibrated amplitude and phase of the crosshand
correlations against frequency channel.
Comments.
It was a single polarization experiment.
TSYS against time.
Comments.
No Tsys for Westerbork. Continuous Tsys measurements are available for all telescopes except Ur and Yb (and Wb). Tsys data look very good.
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.
Ef: gain is higher than expected at the beginning of the observation (bad weather)
Mc: in the lower IFs it is less sensitive while at the highest frequencies the telescope seems to be more sensitive than expected from the EVN Status Tables
Sh: less sensitive than expected
Ur: sensitivity is better than expected in R1-12
Yb: R7-8 and R13-16 are much less sensitive; R9-12 more sensitive than expected
Fringe-fit phase solutions.
Comments.
Phase stability looks good at all stations in general.
Ef: R16 is dead (see above) => Mc is the reference antenna
Wb: stopped observing after second scan
Sh: no fringes in R11 and R12 (BBC 6 upper and lower sideband)
Yb: 2 hours of data is lost (see general comments)
Fringe-fit delay solutions.
Comments.
Delay residuals are generally low (<50 ns), except in Wb (~ 100 ns). Also see notes on Wb uncalibrated phases.
Fringe-fit rate solutions.
Comments.
Fringe rate is less then 5-6 mHz for all telescopes (well, reaches 8 mHz for Sh - still very low).
Telescope bandpasses.
Comments.
Wb: large phase variation across the band - this means that AIPS in fact failed to fringe-fit Wb properly (se notes on delay above)
Calibrated amplitude and phase against time
(a priori amplitude calibration and fringe-fit solutions applied).
Comments.
Bad fringe-rate solutions cause high residual phases in some cases (e.g. near 17:15 in many IFs).
Calibrated amplitude and phase against frequency channel.
Comments.
Phases are not well aligned in many cases at the beginning of the experiment (Ef is not available as reference antenna, Mc was used instead).
Ur: R4 and R11 (BBC 3 and 11 upper sideband, respectively) low amplitude is not calibrated by Tsys
Yb: R9-12 have low amplitude (this must be a Tsys problem, see notes on gain)
Wb: only a few minutes of data seems to be useful
Phase corrections applied to a priori calibrated and fringe-fitted data by self-calibration.
Comments.
Amplitude corrections applied to a priori calibrated and fringe-fitted data by self-calibration.
Also available as a text file.
Comments.
Corrections are low in general for all telescopes except Wb.
Ef: very high correction in R15, almost a factor of 3 in Tsys (see comment on low amplitude above)
Ur: very high corrections in R4 and R11, corresponding to a factor of 6 in Tsys (see notes on low amplitude above)
Yb: R7-8, R14-16 corrections are high, corresponding to a factor of 2 in Tsys (see notes on low sensitivity above)
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.
Ef: R15 is much less sensitive than expected from the EVN Status Tables (SEFD = 20 Jy)
Ur: R4 and R11 are much less sensitive, see notes above (SEFD=396 Jy)
Sh: somewhat less sensitive than expected (SEFD = 590 Jy acccording to the EVN Status Table)
Residual closure phase (visibility closure phase with
model closure phase subtracted) for DA193.
Comments.
Calibrated visibilities and the source model of
DA193.
Comments.
Model agrees with the data well.
Crude map of DA193 from the pipeline.
Comments.