TITLE:   GCN CIRCULAR
NUMBER:  20849
SUBJECT: SN MASTER OT J042250.16-820415.4 is the possible optical counterpart of the gravitational  waves event LIGO/Virgo G274296 
DATE:    17/03/11 17:23:15 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov2007@gmail.com>

V.M. Lipunov, E. Gorbovskoy, N.Tyurina, V.G. Kornilov, 
P.Balanutsa, A.Kuznetsov, V.Shumkov, O.Gress, M.I.Panchenko, A.V.Krylov, 
I.Gorbunov
Lomonosov Moscow State University, Sternberg Astronomical Institute

R.Podesta, C.Lopez, F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA) , National University of San
Juan, Argentina

H. Levato, C. Saffe
Instituto de Ciencias Astronomicas de la Tierra y del Espacio (ICATE),
San Juan, Argentina

N.M. Budnev, O. Gress, K. Ivanov
Irkutsk State University

D.Buckley, S. Potter, M. Kotze,
South African Astronomical Observatory

R. Rebolo, M. Serra-Ricart, G. Israelian, N.Lodiu
The Instituto de Astrofisica de Canarias

A. Tlatov, V.Sennik, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

V.Yurkov, Yu.Sergienko, A.Gabovich
Blagoveschensk Educational State University, Blagoveschensk


MASTER-OAFA (Argentina) auto-detection system discovered  MASTER OT 
J042250.16-820415.4 as bright OT
  at (RA, Dec) =  04 22 49.70 -82 04 10.0  on 2017-02-19.12023UT  during 
inspection (Lipunov et al. GCN 20696, GCN 20711)
  of LIGO/VIRGO G274296 event (Peter Shawhan, GCN 20689) 
http://master.sai.msu.ru/static/OT/MASTEROTJ042250.16-820415.4.jpg  .

This SN is located near the maximal probability area of southern part of 
this GW event error-box.

MASTER-SAAO started inspection of this SN every night with W,B,I,R and V 
filters (21 nights at this moment).
We have good accuracy of its photometry, i.e. the detailed registered 
WBIRV light curve before and during its maximum. "W" - is the unfiltered.

This SN is in 2.6E,11.9N offset from the center of galaxy with low surface 
brightness ESO015-010 (PGC014998) with Btc =16.54m
and Bri25=24.63m (mean surface brightness within 25th-mag isophote).

On the 25th of Feb 2017 PESSTO detected its type (Ia) and z=0.02 (Nyholm 
et al. ATel #10131)

We carried out a preliminary joint analysis of the light curves of 
MASTER OT J042250.16-820415.4 with respect to  supernovae of the similar 
brightness in order to determine the time of explosion of this supernova.

Figure  http://master.sai.msu.ru/static/MASTEROTJ042250.16-820415.4.png 
shows that   MASTEROTJ042250.16-820415.4
supernova reach maximum brightneses ~ 15 days after LIGO G274296 trigger. 
This fact shows that the SN explosion time is very close to the LIGO 
G274296  trigger and this SN could be the progenitor of this event.

The    ESO 15-10 galaxy photometrical distance  is about 84.6 Mpc  for 
Omega_Lambla=0.7+-0.1, Omega_tot=1 an H=72+/-2 km/s/Mpc. The maximal 
magnitute in B filter is about

M(B) = -19.5+/-0.1

The error  include the uncertainty of the cosmological parameters.
This is preliminary analysis of the observations.
Recently one of us  noted  that double O-Ne-Mg white dwafs merging can be 
produce powerfull non spiralling waveform gravitational waves  for 
LIGO/VIRGO type interferometers (Lipunov V.M.,   arXiv: AstroPh, 
submission number 1830243; will be appear
13.03.2017; submitted to New Astronomy).

So we conclude that SNIa MASTER OT J042250.16-820415.4 in ESO 15-10 galaxy 
is the real optical counterpart  of the  gravitational 
waves event LIGO/Virgo G274296 .

All observations are required.