[GMVAtech 61] Re: GBT Calibration data for C212A & B

[Thomas Krichbaum]

Dear Tapasi,

sorry for my late reply, I was on travel.

Thanks once more for the observations and logs. In your
email below you mention 3mm fringe and performance checks.
In principle this is a very good idea, also in view of future
GMVA runs (eg. in March/April 2022, with ALMA).

Prior to each GMVA run we organize such fringe tests, however so far
only for the European GMVA stations. This is mainly because
of logistical reasons. The European telescopes record on FlexBuff, which allows
the Bonn correlator to fetch small portions of data via fast internet lines within 10th of minutes.
It would be quite a challenge to organize such fringe test more globally, also in view of the limited
mutual visibility of bright enough sources and the data transfer to the Bonn correlator.

I wonder if such fringe checks could be performed with some VLBA stations only,
eg. with VLBA+GBT at a time before the GMVA session ?
As I understand the VLBA (and HSA) is also used for regular 3mm VLBI outside the
regular GMVA sessions, and occasionally the GBT could participate in other 3mm runs
and/or NRAO internal technical tests to further optimize its performance.

For a discussion of this and other technical questions, I refer to the 'gmvatech'
group, with the following address: gmvatech <gmvatech at lists.mpifr-bonn.mpg.de>.
I cc to Helge Rottmann, who is in charge of this.


kind regards, Thomas






On 12/10/2021 21:20, Tapasi Ghosh wrote:
> Hi Jim,
> 
> With Frank Ghigo's invaluable help, I do have the calibration files for
> those two GMVA runs for the GBT. I will send you and Thomas the four
> relevant files in a separate email as attachments right after this current
> note.
> 
> We note an important point here though. The first two of the four 
> frequency channels seems to be showing either 'o' or unreliable values. We
> have checked the frequency setup etc.,  and nothing seem obviously wrong.
> So, we wonder if there has been some other issues with the RDBEs or the
> Mk6 recorder. We also wonder if the science data on those two channels
> correlated or not. Given the sporadic nature of GMVA sessions at the GBT,
> it might be good to include the GBT in the fringe tests for any future
> sessions.
> 
> Many thanks, and with all best wishes,
> Tapasi
> 
> 

-- 
Dr. Thomas P. Krichbaum
Max-Planck-Institut fuer Radioastronomie
Auf dem Huegel 69
D-53121 Bonn / Germany

Mail: tkrichbaum at mpifr-bonn.mpg.de
Tel.: (Germany +49)-228-525-295
Web : http://www.mpifr-bonn.mpg.de/research/vlbi