Famous UXOR VX Cas has modest neighbour NSV 183, which even with 800 observations was not marked in VSX as variable. In ASAS database it has uncertain Var type, phase plot shows clear sinusoidal variability like Rot or EW. Is there a chanse to find type of NSV 183?
Looking at the GAIA3 spectrum of the star indicates a spectral type of A0/2V. I am not familiar enough with variability types to know what sorts of early-A stars have periods near 1.5 days.
\Brian
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Thank you, Brian! There are just 12 EW type A0 stars in VSX, and only pair of them have period a bit of longer 1d… There are just 31 EW stars (all types) with periods from 1.4 to 1.6d. So EW probability is small, I think.
Sebastian can surely weigh-in here, but given the small amplitude probably it is some sort of pulsational variable.
\Brian
Greetings,
Very small amplitude… Have you looked at and phased at your 1.485d period the most recent AAVSO data? What does that look like?
Almost impossible to guess what type of variable it might be purely from a phase-folded light curve even with a spectral class. Many questions include: Is the variability and/or period determined real and correct?
If what is shown is real then perhaps it could a very low-amplitude anomalous cepheid. OGLE has found a few in the LMC. Gaia parallax is available and is 0.93 marcsec so you can get a rough Absolute magnitude without reddening correction. I get about +1.83 or so. Probably too faint for any RR Lyr or Cepheid. TESS has found stars called Short-period pulsating hot subdwarf stars (sdbV) but those are much, much hotter objects than what is implied.
I wouldn’t bet the farm on any of the above!
No warranty is expressed or implied in this response–but just some fun musing while waiting for darkness!
Jim (DEY)
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Hi Mikhail,
if it was an EW the period would be twice as long (two minima per cycle), thus excesively long. But also the amplitude and shape of the light curve rule out an EW classification.
It is classified as B9 in 2024AJ…168…25G and that, coupled with the small amplitude, suggest an SPB classification. The period is fine for these Slowly Pulsating B variables.
An alternative is an ellipsoidal variable, in that case the period would be double, the same as with an EW, but amplitude and symmetric shape is more consistent with that.
I think SPB is more likely but at A0 they disappear, so, if A0/2 is okay, that supports the ELL classification.
Have you checked TESS data? It might reveal different amplitudes from cycle to cycle, what would confirm the pulsating solution.
Jim, about the absolute magnitude, if the star is B9-A0, B-V should be around 0.0, which makes determining the color excess rather straightforward.
With APASS B-V of 0.34 and V= 12.16 from Gaia DR3, I get MV= -0.14, which is consistent with a B9V star.
Mikhail, you can submit a revision to VSX 
Cheers,
Sebastian
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Thank you, Sebastian!
Regretfully, I did not find TESS data on NSV 183, but there is flux curve of close VX Cas. So I have no ideas on revision except VAR type instead of “–” 
VX Cas flux
KWS gives light curves for some objects on one plot, and I do not know how to select NSV 183:
003127+6157.5
003126+6157.6
003127+6157.7
There were lots of TESS observations.
The period 1.485 d. was spurious. The real period is 3.0615 d.
ASAS-SN data is too scattery to determine the period.
I revised the VSX entry.
You can check the phase plot.
Cheers,
Sebastian
About KWS data, that’s the data for NSV 183, but you have to keep in mind that if the data show +/-0.5 mag. scatter and variations are in the 0.05 mag. level, this dataset is completely useless.
Each dataset is useful for different purposes at different magnitudes. This star is faint for KWS and has a small amplitude for most surveys. You need to use TESS to properly analyze it. Everything else will be trying to see something in the middle of the scatter, and you may get wrong results.
A lot of thanks, Sebastian! Status of modest UXOR’s neighbour rapidly increased! It even helped to research an evolution of Galaxy structure!!!
Would you please explain, how did you find TESS data? Neither MAST portal nor Peranso did not helped me…
Hi Mikhail,
The data ara available through the MAST site.
What I recommend doing is shrinking the field of view to the smallest size by moving the bar in the left panel. Then you will have the data available for your star of interest only.
I prefer the QLP products. Select them and click on the download basket to add them and save them to your drive.
Cheers,
Sebastian
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Thank you again, Sebastian!
Regretfully, I can not find QLP on MAST Portal. Would you please send direct link?