[GMVAtech 77] Re: NRAO using planobs

[Thomas Krichbaum]

Hi Eduardo,

following Roberts comment on new DPFUs for the VLBA at 3mmm, I actually found that for most
antennas the latest entries are from 2019. This is the time when the VLBA switched to the noVME
operation.

I attach a copy of the vlba_gains.key file, which I fetched today from the /astronomy account
(http://www.vlba.nrao.edu/astro/VOBS/astronomy/). From file I extracted the 3mm-only band and
printed the two most recent entries for the DPFU.

I am astonished to see that no new measurements were made after November 2019 (except LA, PT which
are from 04-2022 and 12-2022, respectively). Comparing the last two gain measurements I also
see a strong discrepancy between RCP and LCP DPFUs for some stations, also being much lower
than before 2019. Below I list the latest entry for the DPFUs:

NL       GAIN ALTAZ   DPFU =  0.012, 0.007   very low LCP, was 0.016 in 2017
FD       GAIN ALTAZ   DPFU =  0.015, 0.033   low RCP, was 0.023 in 2017
LA       GAIN ALTAZ   DPFU =  0.033, 0.036
PT       GAIN ALTAZ   DPFU =  0.012, 0.025   from 2020, much lower than in 2019: DPFU =0.062,0.043
KP       GAIN ALTAZ   DPFU =  0.024, 0.020
OV       GAIN ALTAZ   DPFU =  0.034, 0.035
BR       GAIN ALTAZ   DPFU =  0.027, 0.026
MK       GAIN ALTAZ   DPFU =  0.016, 0.026   lower than in 2016: DPFU=0.030,0.034

I note that the DPFUs are also often lower than the reference values given in Table 5.2
of the VLBA Observational Status Summary 2024B (https://science.nrao.edu/facilities/vlba/docs/manuals/oss/bands-perf).

If we are going to update the sensitivity calculators, I wonder which values we should plugin ?

Ideally it would be great if NRAO could re-measure the DPFUs for all antennas, given the fact
that the lastest entries date back from 2019 and 2020.

kind regards, Thomas

PS: I already fixed the minor spelling issues on the GMVA web page.


>>> Begin forwarded message:
>>>
>>> *From: *Robert Minchin <rminchin at nrao.edu>
>>> *Subject: **Re: Draft text for GMVA call for 31jan2024 {External}*
>>> *Date: *November 30, 2023 at 01:17:32 GMT+1
>>> *To: *Eduardo Ros <ros at mpifr-bonn.mpg.de>
>>> *Cc: *p222rwp <rporcas at mpifr-bonn.mpg.de>
>>>
>>> Dear Eduardo,
>>> Thanks. I’ve looked this over and had a few comments:
>>> It should probably mention that only eight of the VLBA antennas are equipped with 3mm receivers and that the SEFDs have recently 
>>> been revised so older sensitivity calculations will need to be re-done.
see above, for the GMVA calculator (http://www3.mpifr-bonn.mpg.de/cgi-bin/mobs.cgi)
we use 'optimistic' DPFUs, i.e. the higher DPFU from LCP and RCP

>>> We are asking that GMVA proposals use the EVN ‘planobs’ tool for the upload to the PST rather than the old calculator (following 
>>> the problems with ALMA and the old calculator last year), it would probably be good to note this requirement.
>>> Minor comments:
>>> The asterisks in front of the ‘SEE ALSO…’ note near the top of the page are confusing with an asterisk also being used for th
>>> GBT footnote, it might be good to use ‘+ SEE ALSO…’ instead.
>>> There is one instance of ‘polarisation’ (British and international spelling) with most instances being ‘polarization’ (US and 
>>> Oxford spelling). It might be good to harmonise (or harmonize?) these.

done

>>> Cheers,
>>> Robert
>>>
>>> *From:*Eduardo Ros <ros at mpifr-bonn.mpg.de>
>>> *Date:*Tuesday, November 28, 2023 at 1:19 AM
>>> *To:*Robert Minchin <rminchin at nrao.edu>
>>> *Cc:*p222rwp <rporcas at mpifr-bonn.mpg.de>
>>> *Subject:*Draft text for GMVA call for 31jan2024 {External}
>>>
>>> Dear Robert,
>>>
>>> I shared this draft text for our proposal call for January 2024 with ALMA (for 2025 Session I), they say it is OK.
>>>
>>> I will check this here also with Helge Rottmann (correlator).  I will not add the three antennas of IRA/INAF until we do sign the 
>>> Memorandum of Understanding with them, since they have ready the 3mm receiver in Sardinia and they will commission it during 2024 
>>> in Medicina and Noto.  We also plan to have the 3mm receiver ready in APEX in spring 2024, but I will not put this yet in the 
>>> call.  If we need to add these antennas to the proposal tool, I will let you know.
>>>
>>> Could you please have a look as it is?
>>>
>>> Best wishes,
>>>
>>> Eduardo Ros
>>>
>>
> 
> With kind regards,
> 
>                     Thomas
> 
> -- 
> Thomas P. Krichbaum
> Max-Planck-Institut für Radioastronomie
> Auf dem Hügel 69
> D-53121 Bonn / Germany
> 
> Tel. :  (Germany +49)-228-525-295
> Fax :   (Germany +49)-228-525-229
> e-mail:tkrichbaum at mpifr-bonn.mpg.de
> URL:http://www.mpifr-bonn.mpg.de
> 

-- 
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
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