I have been surprised by absence of comp stars for SN 2025rbs. Maybe there are limitations caused by its position?
Everyone uploading data for SN 2025rbs appear to be rolling their own sequences. One is using the rare published Arp supernova search charts.
Do you know how to request a new sequence be made?
Jim (DEY)
Peter Stetson has BVRI data for the field at:
The V sequence goes from 13.4 down to 19.5 with mean errors mostly < 0.015.
One could also use the existing ATLAS refcat2 data for g,r,i, perhaps transforming if necessary.
\Brian
It is just that if noone requests a sequence and there wasn’t a supernova before in the same galaxy that has had a sequence made, then there is no reason for comp stars to be shown in that field, since the AAVSO charts (for now) show sequences made on demand.
You have to request a sequence sending an email to compstars@aavso.org
including the information required here.
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In case it is of interest, here are coords and UBV data for the stars observed by Arp in this galaxy. Source paper + chart is in 1961ApJ…133..883A. Note that for the first two entries the data were determined photgraphically; the rest are from photoelectric photometry using the Palomar 200-inch telescope. I would assign mean errors of 0.05 for the two photographic stars, and 0.03 to the photoelectric data (Arp gave no uncertainties).
\Brian
Name RA (J2000) Dec V B-V U-B
NGC 7331 Arp A1 22 36 57.1 +34 28 01 13.63 0.58 1" cpm pair
NGC 7331 Arp A2 22 36 57.71 +34 28 33.8 13.40 1.04
NGC 7331 Arp A 22 37 01.78 +34 23 54.0 15.05 0.68 0.11
NGC 7331 Arp B 22 37 00.59 +34 24 19.1 15.62 0.71 0.18
NGC 7331 Arp C 22 37 06.87 +34 23 57.5 15.02 0.72 0.22
NGC 7331 Arp D 22 37 08.47 +34 26 12.1 14.08 0.61 0.07
NGC 7331 Arp F 22 37 01.91 +34 26 27.8 16.07 0.79 0.44
Thank you folks for the replies, I’ve sent the request finally.
(Un)expected trouble with bright galaxy core: in spite of not very bad image of SN,VPhot shows absolutely oversaturated spot, and manipulations with limits in Image Display do not help 
BTW, there was SN 2014С in the NGC 7331, but comp stars have not been selected - probably, due to problems with photometry weak SN had just 5 observations.
Wow, Roger Venne prepared excellent sequence for SN!
Even awful black galaxy on the VPhot image does not prevent to correct star detection and evaluations. Gotten CR, TG and TB magnitudes are fully realistic, in spite of the first impression.
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That’s great!
I did some Seestar photography of the galaxy and noticed the Supernova was easily visible in the image. I did not attempt the photometry yet.. Looks like you’re getting great results in VPhot so I’ll try.
Well, background is very bright: SNR of SN is about 30, when comp stars have SNR 300-800. Obviously, SN spot will dissolve in the galaxy shine soon.
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