P.I. letter
To: Xu
Subject: EX009 FITS files ready on the EVN Archive
Dear PI,
We have examined your project (EX009,15/09/2020) and the
data are ready for distribution to you. You can download the data
directly from the EVN Data Archive (see below). Contact your support
scientist to arrange a password for your experiment.
The experiment scheduled the following telescopes: JbWbEfMcNtO8T6YsHhZcBdIrKmCmDaDeKnPi.
Your experiment was processed with the following parameters:
Pass1: 18 Tels, 8 band X 2 pols, each with 128 points, 2 sec int.
The originally recorded disks from the stations can be released after
two weeks. If you have any questions, contact us at jops@jive.eu.
EVN and Global VLBI Observations correlated at at JIVE are now
automatically calibrated via a pipeline process. You will receive email
notification when the pipeline is complete. In particular, the a priori
amplitude calibration table (and the associated, final ANTAB file -- note
that it is better to use this file from the pipeline rather than the
individual-station antabfs files available from the "Station Logfiles"
tab of the archive), plus various other tables and plots will be available
to download from the EVN archive (subject to the EVN Data Archive policy as
discussed below). A description of the pipelining process can be found at:
www.evlbi.org/pipeline/user_expts.html
The EVN data archive at JIVE is now a central location for obtaining
the information you need in reviewing your project. You can find
network feedback from the stations, standard plots from the correlation
review done here prior to distribution, pipeline results, and the FITS
files themselves. Contact your support scientist to arrange for a
password with which you can download your FITS file(s) from the archive
directly. See the EVN Users' Guide in www.evlbi.org for a link to the
EVN Archive policy -- in short, data from sources you identified as
target/private in pre-correlation e-mail will not be made public, nor
will pipeline images be available from them, for one year from
distribution. The archive can be accessed via:
www.jive.eu/select-experiment
(or via the menu items of the main jive page www.jive.eu). Once in
this portal to the EVN data archive, you can click on your experiment
in the pull-down menu in the "Select Experiment" window; then click on
the link "Show Experiment" that will appear immediately below this.
You will then see a new window for your experiment, from which you can
select from the various sorts of data available from the menu row along
the top:
*) Station Feedback = information provided by the stations' VLBI friends
about the conduct of the experiment
*) Station Logfiles = sched-based files you uploaded to VLBEER, observing
log-files from the stations, other unprocessed station-generated files.
*) Standard plots = the plots described below in a variety of formats,
a copy of this cover letter
*) Pipeline = pipeline plots; the ANTAB & UVFLG files used in pipelining
*) Fitsfiles = FITS files, plus an associated README in case there are
multiple correlator passes each with its own set of FITS files.
The proprietary period for data on the EVN archive is 1 year (6 months
for target-of-opportunity observations) -- the raw FITS files and pipeline
results relating to sources you identified as "private" receive password
protection during the proprietary period. For more details, see
www.evlbi.org/user_guide/archive_policy.html
Papers that result from your EVN observations should carry the
standard EVN acknowledgment:
The European VLBI Network is a joint facility of independent European,
African, Asian, and North American radio astronomy institutes.
Scientific results from data presented in this publication are
derived from the following EVN project code(s): EX009
If your observations included e-VLBI segments or were eligible for
RadioNet support, please visit
www.evlbi.org/index.php/acknowledgements
for the further acknowledgments to include in your papers.
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General Remarks:
In the process of checking your experiment we have created plots of
the weights vs time, auto- and cross-correlation spectra for a few
one-minute intervals, and the behavior of amplitude and phase in time.
These plots and an explanatory description can be found in your
experiment's standard plots section of the EVN data archive.
As part of the check-out procedure, we evaluate the quality of all
data with low weights and set an appropriate cutoff for flagging.
In this experiment the cutoff was set at 0.85.
This cutoff flagged 0.0% of the data.
If you observed with 2-bit sampling, your data have been corrected
with a van Vleck correction to account for the statistics of high/low
bits for each BBC's data stream at each station. Thus you shouldn't
run ACCOR in AIPS. It should be okay to use autocorrelations for
bandpass corrections or to use ACFIT. For AIPS versions starting
with 31DEC13, you should set DIGICOR to -1 in FITLD (previously, it
would do that automatically if the array was not VLBA).
Remarks on plots or individual stations:
Jb:
Wb: Observed IFs 5-8 due to limited bandwidth.
Ef:
Mc:
Nt: Joined few minutes later. Clock time updated at 19:28UT
Expect a larger delay before that time.
O8:
T6:
Ys:
Hh: Out for most of the observation due to cooling fan failures.
Zc: Could not join.
Bd: Joined at 20:00UT.
Ir:
Km: Observed IFs 5-8 due to limited bandwidth.
Cm: Observed IFs 6-7 due to limited bandwidth.
Da: Observed IFs 6-7 due to limited bandwidth.
De: Observed IFs 6-7 due to limited bandwidth.
Kn: Observed IFs 6-7 due to limited bandwidth.
Pi: Observed IFs 6-7 due to limited bandwidth.
Further remarks:
Note that Kunming (Km) and Noto (Nt) may be lost for some intervals along the oservation.
The first scan on each target would likely need to be flagged due to the slewing times that stations require to move from one target to another.
Badary (Bd) seems to exhibit larger amplitudes on the Right polarization (RCP), that may require a gain correction factor of ~0.5 only on that polarization. LCP amplitudes seem to be OK.
Please, calibrate carefully the eMERLIN stations (Cm, Da, De, Kn, Pi). The provided short baselines may produce a more challenging calibration.