I wondered why PX Dra was brightest in V.
This season I went looking for Gaia and found that comp 103 was a 40 mmag Gaia. The PX Dra light curve had ~ 40 mmag of noise on it. Deleting that comp made PX Dra brighter in I-band. Another season will tell if the 40 mmag of noise went away. I requested an AUID for Gaia DR3 1619736556503451520 .
Hi Ray,
it is brightest in V because the comparison star 103 actually varies between V= 10.53 and 10.56. Its APASS value used for the comparison star database is contaminated by PX Dra itself that it is 18" away but it is too bright so light coming from it is included in the fainter star measurement.
The different magnitudes in the plot do not make sense for an F-type star, the Ic and B can’t be that similar and V can’t be that brighter.
So remove this object as a comparison star, I have already done so.
Update the chart and use another comp and see what magnitudes you get.
I will ask the Sequence Team to find another comp star in the field.
I see that the 103 did not have Rc and Ic values in VSD, so you were using other comp stars for these bands?
Cheers,
Sebastian
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I agree.
I’ll need to go back and redo it with the new comps.
Not likely to follow the 30 mmag gaia here, I probably cannot isolate it reliably in the the night to night imaging.
Ray
I just made the same sad discovery with AU CrB. My CR curve lays below AAVSO V and CV, well as ASASSN g. Ironically, my CR range is close to VSX R1, and I was calm until compared results.
There are no AAVSO comp stars for AU CrB, so I suspected Astap algorythm. Now understand the true reason of anomaly.
The timing is OK, so I think to leave data in VSX. Absolute values are not so important for extremums moments, but shift is unpleasant.
Sorry Mikhail, I don’t understand what the issue is here, mostly because I don’t have any idea on what each dataset is. It is important to explain the colors in plot, otherwise one doesn’t know which band is which and if the differences between them make sense.
There aren’t any nearby stars so the ASAS-SN V and g magnitudes (you should add V for comparison with AAVSO V) should be okay.
The period has to be improved. There is a 0.2 offset in phase for some of the datasets.
Cheers,
Sebastian
Phase plot was corrected, thank you for the admonition.
All my attempts to find more suitable period were unsuccessful. I suspect extremums offset in different bands, typical for pulsators.