I’m using Phoranso for photometric reduction and have run into a recurring but inconsistent issue with the catalog lookup.
When running “Load Catalog,” the APASS DR10 query sometimes fails to return data for my field,
and when Phoranso falls back to my local UCAC4 copy, that occasionally fails too — leaving me with no reference stars found in the FoV at all.
It worked fine twice this morning — but the failures I’ve seen in Phoranso don’t correlate with a fixed field or time of day;
it seems to depend on which FoV/coordinates are being queried. Quite puzzling, since it’s not a simple “always down” or “always up” situation.
I’ve reached out to Tonny directly, but wanted to ask here as well:
Has anyone else experienced this field-dependent behavior — DR10 lookups working for some FoVs/coordinates but not others?
Does anyone know whether specific fields, star densities, or coordinate ranges are more prone to failing on the AAVSO side?
Another suggstion is to use APASS DR9 from the CDS VizieR catalogue-query service. It is item II/336. Bear in mind also the caveat in the Web page description of DR10: “The photometric errors appear to be worse in DR10 than in DR9.” Seems like one should prefer using DR9 in any case.
Update: meanwhile it seems that the problem to reach the APASS DR10 data might have been a connection error on that specific day.
This may be caused by the way the Phoranso Software queries the AAVSO server or by unavailability of the server (I checked of course other internet connections, e.g. SIMBAD/VizieR).
So, most of the time everything works well
CS!
Hi Dieter,
I have also noticed complete missing FOV’s, gaps and errors in DR10 on several occasions. Therefore I’ve developed a cross-matching script looking up APASS DR10 (from the gavo Heidelberg service) and Gaia DR3, to avoid using APASS DR10 data without checking. For example if you look-up the Landolt standard field SA35, there are absolutely no APASS data around, but Gaia DR3 is fine. On another occasion I found an APASS DR10 field result where all magnitudes above 14 were exactly one magnitude off. So I like APASS because it has a lot of photometric data in fields with insufficient AAVSO comp stars, but it’s safer to double-check against another database before using it. Gaia DR3 color transformations are good enough to spot APASS DR10 mismatches or abnormalities. I’ve done that on a few dozen 30 arc min fields where I search for the 100 best photometric field candidate stars. That identified several fields with APASS issues, sometimes minor.
