[vsnet-grb-info 16622] GRB 150518A: possible SN observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17903
SUBJECT: GRB 150518A: possible SN observations
DATE:    15/06/06 15:19:15 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

A. Pozanenko (IKI), E. Mazaeva (IKI),  A. Sergeev (IRA NASU, IAKhNU), I. 
Reva (Fesenkov Astrophysical Institute), A. Volnova (IKI),  E. Klunko 
(ISTP), I. Korobtsev (ISTP), report on behalf of larger GRB follow-up 
collaboration:

We observed the field of the MAXI/GSC GRB 150518A (Kawamuro, et al., GCN 
17825) with AZT-33IK telescope of Sayan observatory (Mondy), Zeiss-1000 
(East) 1-m telescope of Tien Shan Astronomical
Observatory and AZT-22 telescope of Maidanak observatory.
Observations are continuing in R-filter. The SDSS J153648.25+161946.9 
galaxy which coincides with the optical afterglow (Xu et al., GCN 17829) 
is  detected in all observations. The light curve of the host 
galaxy+afterglow are suggesting re-brightening with a possible maximum 
brightness on June 2-5.  We suggest that this re-brightening can be 
attributed to Supernova associated with GRB 150518A.  Preliminary light 
curve of the possible SN+host can be found in 
http://grb.rssi.ru/GRB150518A/GRB150518A_lc.png

Photometry of the host galaxy+SN at the possible maximum brightness  are 
following

Date       UT start   t-T0     Filter     OT    Err.  Observatory
                       (mid, days)

2015-06-02 17:43:30   14.8605  R          20.89 0.13  TSHAO
2015-06-03 20:33:20   15.8862  R          20.82 0.10  Maidanak
2015-06-05 18:11:19   17.8535  R          20.90 0.07  Maidanak

Photometry is based on SDSS DR9 stars:

SDSS9_id            R(Lupton)
J153646.11+161904.1    17.65
J153638.21+162002.8    18.41
J153637.55+162040.3    17.10
J153645.59+162055.5    16.35

The maximum brightness of a the possible Supernova is an agreement with 
the brightness predicted for the SN at redshift z = 0.256 (Xu et al., 
GCN 17832).