Counterpart of MASTER OT J084140.94+722732.6

ATel #8731; Roberto Nesci (INAF/IAPS)
on 25 Feb 2016; 10:29 UT
Credential Certification: Roberto Nesci (Roberto.Nesci@iaps.inaf.it)

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Following the ATel #8725 by Balanutsa et al. about MASTER OT J084140.94+722732.6, I made aperture photometry on all the Palomar survey plates (12) available from the MAST archive to get an indication of the star color. The star is positionally coincident with NSV 4186 , first detected in 1926 by F.E. Ross (ROSS 166, AJ 37, 91, 1926) and is listed in the GSC 2.3.2 catalog as N7TV002683. Photometry was made with IRAF/apphot using the stars in the GSC 2.3.2 catalog down to V= 18.8 as comparison sequence within 6 arc-min (62 stars). A linear calibration from instrumental magnitudes into catalog ones worked well for non-saturated stars (fainter than V=15.6).

 
plate band mag   err   date 
quick  V   18.19 0.16 1984-02-06 
quick  V   17.80 0.15 1983-11-05 
possI  E   19.05 0.17 1955-01-25 
possI  E   18.95 0.19 1953-02-18 
possII R   19.41 0.14 1995-02-03 
possII R   18.62 0.12 1997-02-10 
possII N   18.40 0.13 1996-12-19  
possII N   18.38 0.09 2000-04-09 
possI  O   18.66 0.22 1955-01-25 
possI  O   18.74 0.24 1953-02-18 
possII B   19.24 0.15 1997-11-28 
possII B   19.17 0.13 1996-12-07 

It is clear from this historical data that the star was always detected in quiescent states. In the color color plots (B-V vs V-R, and V-R vs R-I) the star is the bluest in the field, as expected for a dwarf nova. This finding supports its identification as the actual counterpart of MASTER OT J084140.94+722732.6