[vsnet-outburst 18575] MASTER OT J021211.74+475602.7 = ASASSN-15nt

[Taichi Kato]

MASTER OT J021211.74+475602.7 = ASASSN-15nt

   According to ASAS-SN Transients page, MASTER detected
this object earlier.  We use the name
MASTER OT J021211.74+475602.7.

===

ATEL #7861                                                           ATEL #7861

Title:  MASTER-Kislovodsk: bright dwarf nova outburst
Author: S. Shurpakov, V. Lipunov, E. Gorbovskoy (Lomonosov MSU, SAI),
                N. Samus (INASAN, Lomonosov MSU, SAI), N. Tiurina, P. Balanutsa, A.
                Kuznetsov, V. Kornilov, I. Gorbunov, V. Chazov, D. Vlasenko (Lomonosov
                Moscow State University, Sternberg Astronomical Institute), A. Tlatov,
                D. Dormidontov, V. Senik, A. V. Parhomenko (Kislovodsk Solar Station
                of the Pulkovo Observatory), D. Buckley, S. Potter, M. Kotze (South
                African Astronomical Observatory), O. Gress, N. M. Budnev, K. Ivanov
                (Applied Physics Institute, Irkutsk State University), R. Rebolo,
                M. Serra-Ricart, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto
                de Astrofisica de Canarias), V. Krushinski, I. Zalozhnykh (Ural Federal
                University), Yu. Sergienko, A. Gabovich, V. Yurkov (Blagoveschensk
                Educational State University)
Queries:        tiurina at sai.msu.ru
Posted: 1 Aug 2015; 07:48 UT
Subjects:Optical, Request for Observations, Cataclysmic Variable,
                Transient, Variables

MASTER OT J021211.74+475602.7 - the discovery of bright possible dwarf
nova outburst (13.6m, Ampl>3m) 

MASTER-Kislovodsk auto-detection system (  <A HREF="http://www.hindawi.com/journals/aa/2010/
349171/">Lipunov
et al., Advances in Astronomy, MASTER Global Robotic Net, 2010</A> ) discovered
OT source at (RA, Dec) = 02h 12m 11.74s +47d 56m 02.7s on 2015-07-31.92043
UT. 

The OT unfiltered magnitude is 
13.6m
(the limit is 17.5m). 
There are 3 images with m_OT=13.6. There is no minor planet at this place.

We have reference images with  OT in quiet state on 2009-10-12.044UT with
R=16.6, on 2010-07-28.927UT with unfiltered m=16.7, on 2011-10-30.901UT
with unfiltered m=16.6,  on 2012-09-19.946UT with m=16.5, on 2013-11-11.802UT
with m=16.6, on 2014-08-22.980UT with m=16.5 . There is USNO-B1 star with
B1=17.53,R1=16.23,B2=17.96,R2=16.75,I=15.82. So we can suggest the dwarf
nova outburst with Ampl>3m 

Spectral observations are required. 

The discovery and reference images are available at http://master.sai.msu.ru/static/OT/02121
1.74475602.7.png

<center><a href="http://observ.pereplet.ru/MASTER_OT.html">List of Optical
Transients discovered by MASTER</a></center>