[Difx-users] DiFX 2.8.1 released {External}

[Simone Bernhart]

Dear colleagues,

I started testing the latest DiFX release on two geodetic experiments, 
one of which was a mixed-mode session (r11094) where two stations (Hb, 
Ke) observed in dual linear polarisation (X,Y) mode and the others in 
single circular polarisaton (R).

When checking the mixed-mode session fringe plots, I noticed that scans 
with mixed baselines show much higher amplitudes (factor of ~4.7) and 
higher SNR than with DiFX-2.6.3 whereas baselines with only circular or 
only dual linear pol show the same numbers as with d263.

For better illustration I attached some plots with mixed baselines, lin. 
pol. only and circular pol. only for both d281 and d263 (I hope the plot 
names are self-explanatory enough). d263 comes with HOPS 3.23 whereas 
d281 goes with HOPS 3.24. However, the slight differences in the numbers 
of the fringe plots stem from correlation or difx2mark4 and not HOPS 
(please cf. plots 072-1702_rq_X_HOPS3.23.ps and 072-1702_rq_X_HOPS3.24.ps)

Initially, I was quite happy to see higher amplitudes and SNR for the 
mixed baselines because it is usually a pain in the neck to find 
adequate scans with high enough SNR for the necessary calibration steps 
of the dual pol stations. But since the 'same pol' baseline fringe plots 
show the same numbers as with the older DiFX version, I assume that 
there is a scaling error somewhere on the way from SWIN to Mk4 files for 
the mixed cases - in particular since I also tested difx2mark4 from d263 
for the d281-correlated data (using option --override-version) and got 
the same results as with the d263 correlation...

Please let me know if you need further data.

Thanks a lot in advance and cheers,
Simone


On 3/30/23 03:02, Adam Deller via Difx-users wrote:
> Hi DiFX users and developers,
> 
> I'm very happy to announce that DiFX-2.8.1 is now publicly released.  
> The ChangeLog for this release can be found at 
> https://www.atnf.csiro.au/vlbi/dokuwiki/doku.php/difx/changelog 
> <https://www.atnf.csiro.au/vlbi/dokuwiki/doku.php/difx/changelog>.
> 
> I'd like to thank everyone who has contributed to this release - there 
> have been very many who have coded, merged, tested, and documented! A 
> special shout out to Walter Brisken for coordinating the final tagging 
> and curation of the ChangeLog.
> 
> Finally, keep your eyes open for some further announcements on plans for 
> the 2023 DiFX workshop later this year!
> 
> Cheers,
> Adam
> 
> -- 
> !=============================================================!
> Prof. Adam Deller
> Centre for Astrophysics & Supercomputing
> Swinburne University of Technology
> John St, Hawthorn VIC 3122 Australia
> phone: +61 3 9214 5307
> fax: +61 3 9214 8797
> !=============================================================!
> 
> 
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-- 
Dr. Simone Bernhart
Reichert GmbH / Bundesamt für Kartographie und Geodäsie
c/o VLBI Korrelator
Max-Planck-Institut für Radioastronomie
Auf dem Hügel 69
53121 Bonn
GERMANY
phone: +49 228 525 479
fax:   +49 228 525 229
email: simone at mpifr-bonn.mpg.de
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