[vsnet-grb-info 21502] GRB 181201A: photometric signature of the SN

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23601
SUBJECT: GRB 181201A: photometric signature of the SN
DATE:    19/01/03 20:40:28 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

S. Belkin (IKI), E. Mazaeva (IKI),  A. Pozanenko (IKI),  P. Minaev 
(IKI), A. Volnova (IKI), N. Tominaga (Konan University), S. Blinnikov 
(ITEP), D. Chestnov (KIAM), E. Klunko (ISTP), I. Reva (FAPI), V. 
Rumyantsev (CrAO),  D. Buckley (SAAO), R. Ya. Inasaridze (AbAO) report 
on behalf of  GRB-FuN collaboration:

We observed  the   optical afterglow (e.g. Podesta et al., GCN  23470; 
Kong  GCN 23475) of the INTEGRAL GRB 181201A  (Mereghetti et al., GCN 
23469)  with   Gemini-N telescope  on Dec. 22 in g'r'i'z and Dec. 24  in 
r'i'-filters.  Preliminary photometry of the OT is following.

Date            t-T0  Filter Exp.   OT     Err.
                 (mid, days)  (s)

2018-12-22  21.10536 i'     3*180  21.50  0.03
2018-12-22  21.09536 r'     3*180  21.82  0.03
2018-12-24  23.09418 i'     3*180  21.32  0.06
2018-12-24  23.10793 r'     3*240  21.83  0.03

The photometry is based on the SDSS-DR12 star
SDSS-DR12_id           i'	r'
J211710.81-123706.3    16.257	16.517

Based on our previous observations and photometry reported in GCNs 
23475, 23478,  23486, 23504 we plot a light curve of the afterglow in 
r'-filter (http://grb.rssi.ru/GRB181201A/GRB181201A_optics_fit.png). 
Power law approximation of the LC before 2018-12-22 has an index of 
1.19 +/-0.01. The photometry obtained on 2018-12-22 and 2018-12-24 has a 
significance of about 2 and 6.5 sigma above the power law approximation. 
Additionally the i'-magnitude increases between  the two epochs. We can 
suggest that we observed the Supernova signature associated with GRB 
181201A.