In VSX are a large number of Gaia DR3 stars. In another thread a discussion includes information that many of them have dubious evidence for their true variability and even more are uncharacterized.
I am data mining my image collection (something over 40K images) and initially I’m paying attention to stars which are in VSX but not in AID. With luck, some of those will be confirmed variable and an example in the field of LS And and a snippet from a PostgreQSL database is given below. It is clearly variable but six points on the light curve are not enough to place it in any given category.
The question is how, and to whom, to report findings such as these?
Paul
name | jd | mag | err
----------------------------±---------------±----------±---------
Gaia DR3 381889186083910272 | 2458457.473449 | 15.86404 | 0.010823
Gaia DR3 381889186083910272 | 2458817.423843 | 16.219902 | 0.007154
Gaia DR3 381889186083910272 | 2458846.468642 | 16.567724 | 0.00524
Gaia DR3 381889186083910272 | 2458869.395041 | 16.400318 | 0.014646
Gaia DR3 381889186083910272 | 2458873.411961 | 16.414312 | 0.017559
Gaia DR3 381889186083910272 | 2459447.481782 | 14.537961 | 0.01448
What would you like to report, given the star is already in VSX?
You could always upload your observations.
If you’d like to refine the VSX entry, consider combine with other archival data to do analysis. A quick check suggests there is data from ZTF and ASAS-SN.
(The ASAS-SN data might be less reliable, given there is a star 12" away, ~0.6 Gmag fainter.)
Thanks,
I may be confused, probably I am, but the VSP page tells me that observations of entries in VSX may not be uploaded to AAVSO but those in AID can be.
This one is in VSX but not, as of earlier today, in AID which suggests that I can’t (or at least shouldn’t) upload my data as you propose. Because I am confused, perhaps the advice could be clarified for the bears of very little brain like me.
Paul
In the world of the large survey many new, low-amplitude, and variability type determined by machine AI classified stars result in many of those stars having incorrect variable type assigned, etc.
You could write a roll-up, summary paper of your results for all the stars you have improved information for in the Journal of the AAVSO. Don’t forget to give your paper and 40K personal survey a catchy name to get the results noticed! 
If your personal 40K survey results produce a huge number of stars with improved information you’ll need to talk to Sebastian to get VSX updated. Still do a JAAVSO paper, of course.
Jim (DEY)
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On uploading data, I’m afraid I don’t know the specifics.
If the concern is that the star lacks an AAVSO UID, it can be requested on the VSX entry page, and is pretty much automatic.
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Paul’s observations suggest this target changes in brightness by 2+ magnitudes. Might be worth investigating this more carefully, that is a large amplitude.
-Kenneth
That is what I thought. However, because it is a field variable of LS And, which spends almost all its life at mag 20 or so, I rarely image it, so only six data points.
Being a life-long pessimist, I really hope this is not a false alarm. 8-(
It may be wise not to spend too much effort in investigating this one as it may be a false alarm after all.
I found some niggling inconsistencies between the photometry measured by the latest software, and that from when I originally measured LS And.
I’m now reviewing the software very carefully and tying to find out what, if anything, may have gone wrong.
Apologies the premature report.
Paul
Even if this is not an actual variable and you “only” refine your data reduction to make it better, that is still a success! Checking and validation is part of the scientific process, and for potentially new variables it is very important that all other possible explanations are considered.
-Kenneth
I have now re-measured the images with the software and sequence data used to measure the originals and the data for which has been submitted to the BAA-VSS. I am rather sure of the quality of the output of that software as all the measurements of well over a hundred variables (bar a couple where the VS was blended with a neighbouring star and so the measurement not submitted) are in good agreement with measurements made by other observers at close to the same time.
JD New Mag New Err Orig Mag Orig Err
2458452.582459 xxxxxxxx xxxxxxxx [19.31
2458457.473449 15.86404 0.010823 15.8626 0.0118
2458817.423843 16.219902 0.007154 16.2225 0.0072
2458840.410090 16.5677 0.0052 16.5665 0.0074
2458846.468642 16.567724 0.00524 16.4959 0.0044
2458869.395041 16.400318 0.014646 16.3978 0.0146
2458873.411961 16.414312 0.017559 16.4188 0.0184
2459447.481782 14.537961 0.01448 14.7302 0.0275
Comments:
With three exceptions, five of the six measurements reported above are in very good agreement between the original and latest versions of the software. I believe that the minor discrepancies arise from addition of extra comparisons to the sequence over the last five year. The observation for MJD 8840.41 was omitted from the original post through a cut and paste error. It too is in good agreement.
On the image for MJD 8452.58 there is a very faint star at the correct position but not measurable to within 0.15m.
The image taken on MJD 9447.48 was of very poor quality with a great deal of sky background. Checking the log book I see that there was a heavy calima (Saharan dust in the atmosphere) on that night.
From my data it would appear that Gaia DR3 381889186083910272is very likely a variable star. The less-than measurement is puzzling. The only hypothesis I have is that it may be a CRB but eight points spread over several years is nowhere near enough data to make a convincing case.
Paul
Hi Paul,
there are archival ZTF data spanning many years in addition to the 42 datapoints from Gaia DR3 that were used to classify the star as a rotational variable with a 0.03 mag. amplitude.
The ZTF data confirms the small amplitude.
This is the r-band light curve:
No period could be found.
The star has V= 16.40.
You don’t mention filters in your posts but some of your observations agree with the V mag.
The object can not be an R CrB star because it is a faint K dwarf, some 10 mag or so fainter than R CrBs.
The spread in your magnitudes is not physical, you should check your images or try to find another explanation for these results.
When wanting to revise existing variables in VSX, it is better to use existing survey data to see the long-term behaviour of the objects and be able to find much more accurate periods if the objects are periodic.
I don’t recommend submitting revisions based on sparse data.
Best wishes,
Sebastian
You are correct: taken with a V filter and I should have mentioned that.
Right now I have no idea what is going on but will try to find out. It is looking like I need to examine my software very closely.
Paul
