What happens with UID requests?

Technology VSX
1

Could someone please clarify how UID requests for existing VSX stars are handled?

I requested a UID for a VSX object (NW Dra), but so far nothing seems to have happened. I understand that some UID requests may be processed automatically, while others may require manual review. Is there a general procedure or guideline for cases where the UID is not assigned automatically?

I also noticed that a similar question about PQ UMa was asked in the forum about a year ago, and that star still appears to have no UID. Since these are not obscure objects, but well-known and relatively bright variable stars, I wonder whether such requests can be declined, remain pending, or require some additional step from the requester.

Would it perhaps make sense to slightly relax the criteria for automatic UID assignment in straightforward cases, in order to reduce the amount of manual review work? Or are there specific reasons why this has to remain rather restrictive?

Thank you for any clarification.

Thomas

1 Like
2

Hello Thomas,
this particular example is different from the rest in the sense that -for some reason- I never got the notification informing your request had been received. But let’s assume that I had got it as usual.

The reason why this one did not get an AUID assigned automatically is the presence of a 15th mag. variable 11" away.
Whenever there is another variable closer than 15", we need to check with the observer if they can solve the two.
There is also the risk of having two stars, one visible to the observer and the other one not, and the observer submitting bright magnitudes for the faint object due to a misidentification. So identification starts to become an issue when there are two variables close to each other.
Once we get confirmation that the observer can safely solve/identify the objects properly, we assign the AUID.

Even with the restrictions applied now (stars fainter than 18th mag., stars with amplitudes <0.02 mag., stars classified as constant or suspect, stars with another variable closer than 15"), we still get a lot of observations of blended objects and wrong IDs. This is especially happening with observers submitting data for every star in their images.
It is very important that images are inspected in order to detect blending or any potential issue like those described above.

Even when you may solve these two stars 11" apart, some other observers may not. This depends on your set up, so everyone should be careful.

Furthermore, we are not checking for the presence of non-variable stars around the targets.
There may be a bright companion 2" away and we won’t know because the star is not in VSX (we might be able to change that in the future with the increasing number of available tools and a new VSX version around the corner), so the checks observers can do before submitting are really important.

Would it perhaps make sense to slightly relax the criteria for automatic UID assignment in straightforward cases

It has been done, if right now a star does not get an AUID is because there is a compelling reason, like the ones above.
If any observers know for sure that their equipment allows them to get good data for targets that do not meet the above requirements, just send an email to me or to vsx@aavso.org so we can be aware that is the case and assign the AUID without much further checking.

Regarding PQ UMa, it was just mentioned by Mikhail Ashchepkau in a forum post but no AUID was requested ever. There are millions of stars without AUIDs because we don’t assign AUIDs to stars added from list imports, to avoid doing it for stars that may fall under the problematic categories already mentioned.
There is no reason why PQ UMa won’t get an AUID assigned auotmatically if someone clicks on the Request AUID button.

Cheers,
Sebastian

3 Likes
3

Hello Sebastian,

thank you very much for the detailed explanation. That makes perfect sense.

I am currently developing my own photometry software, and the case of NW Dra actually helped me find an important weakness in my checks. I do check for contamination of both the target aperture and the annulus, including nearby stars. However, up to now I had only used APASS DR10 for this particular check. In that catalogue, I did not get a clearly identifiable separate nearby star; APASS 155-0874337, at 1.63" from NW Dra, was effectively interpreted as being the same object as the target.

Using Gaia, the situation is much clearer, with the nearby variable separated by about 11.5". So in this case it is absolutely justified that no AUID was assigned automatically. With aperture photometry these two objects are very difficult, or practically impossible, to separate reliably. Depending on the phase, the measured magnitude would be about 0.1 to 0.3 mag too bright.

I have now added the Gaia-based check to my software, and NW Dra now correctly gives a clear “target blend check failed” warning. In my workflow, this means that the star is rejected for measurement.

So thank you again — this was a very useful example, and it helped improve my own validation process.

Best regards,
Thomas

1 Like
4

I see PQ UMa obtained an AAVSO UID now

AAVSO UID
000-BQM-259 (No observations)

. Next, a request to the compstars team?

Ray

5

Thank you, Ray, PQ UMa is not forgotten now :slight_smile:
Of course, compstars are needed in the case of planned observations.

6

Hi Thomas,
There is no star 1.63" away from NW Dra, and if there was, APASS wouldn’t be able to solve it. Stars closer than 11-12" would be measured as a single object. So if you see an APASS entry at such distance, that is indeed NW Dra, not another star. APASS astrometry is not so good either.

Cheers,
Sebastian