[vsnet-grb-info 26497] SGR 1830-0645 / GRB 201010A: Kitab optical non-detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28597
SUBJECT: SGR 1830-0645 / GRB 201010A: Kitab optical non-detection
DATE:    20/10/11 12:42:25 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI), A. Zhornichenko (KIAM), N. Pankov 
(HSE), A. Novichonok (Petrozavodsk State University, KIAM),   Sh. 
Ehgamberdiev (UBAI) report on behalf of IKI-GRB-FuN:

We observed the field of new SGR 1830-0645 (Page et al., GCN 28594; 
Gogus et al., ATEL 14085) originally detected by Swift (trigger=999571) 
and also named as GRB 201010A with Kitab-ISON RC-36  telescope in 
R-filter. Observation started on Oct. 10 (UT) 15:21:08, i.e. 31.7 
minutes after trigger.

The field is extremely crowded. Within  enhanced XRT position (Osborne 
et al., GCN 28596) we found  a source which is also presented in the 
DSS2 (R) image but not listed in USNO-B1.0. In our images we cannot 
discriminate the sources. We performed aperture photometry which include 
this source and nearby Northern source listed in USNO-B1.0 0832-0432584 
(R2=13.54) in two stacked images. The image A is at midpoint 0.02343 
days and the image (B) is at midpoint 0.03835 days after trigger. By 
comparison of the two photometric results (A) R=14.16 +/- 0.06 and (B) 
R=14.20 +/- 0.07 we do not observe any variability and hence we do not 
detect optical activity of SGR 1830-0645.

Formal photometry of the field in both epochs (A,B) is following

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

(A)2020-10-10  15:21:08 0.02343   240    R       n/d    n/d   17.0
(B)2020-10-10  15:21:08 0.03835  2480    R       n/d    n/d   18.0

The photometry is based on nearby USNO-B1.0 star, R2 magnitude

USNO_B10_id  R2
0832-0432530 15.34
0832-0433055 13.04