TITLE:   GCN CIRCULAR
NUMBER:  33191
SUBJECT: GRB 230116D: SAO RAS photometry
DATE:    23/01/17 21:39:47 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI, HSE), A. Moskvitin (SAO RAS), A. Pozanenko (IKI),  A. 
Moiseev (SAO RAS), D. Oparin  (SAO RAS), N. Pankov (HSE, IKI) report on 
behalf of  GRB IKI FuN:

We observed the optical afterglow (Zhu et al., GCN 33177; Nazarov  et
al., GCN 33178; Moskvitin et al. GCNs 33179, 33187; Swain et al., GCN
33182; Belkin et al., GCNs 33189, 33190)  of GRB 230116D (Sonbas et al., 
GCN 33176) with BTA SAO RAS telescope equipped with SCORPIO-2. 
Observation started on 2023-01-16 (UT) 23:31:38. Photometric 
observations consists of r -filter acquisition imaging and  g,r,i - 
filters after before spectroscopy (Moskvitin et al. GCN 33187). 
Preliminary photometry of stacked images is following


Date       UT-start Exptime Filter t-T0     OT     Err    UL
2023-01-16 23:31:48 2*20    r      0.10951  20.29  0.05   21.4
2023-01-17 01:33:17 2*90    r      0.18859  20.97  0.04   23.2
2023-01-17 01:30:43 3*120   g      0.18935  22.18  0.08   23.1

Ref.stars
PanSTARRS-PS1
RA DEC g r i z
06:34:21.9567816 +49:52:11.318772 16.3946 15.7833 15.5155 15.3912
06:34:23.9012808 +49:51:55.541160 18.8105 18.2189 17.9721 17.8591
06:34:37.7805360 +49:50:45.780468 18.3294 17.6554 17.3783 17.2518

The light curve based on afterglow observations (GCNs 33177,  33178, 
33179, 33187, 33188, 33182, 33189, 33190)   can be found at
http://grb.rssi.ru/GRB230116D/GRB230116D_lc_1.png

The light curve  confirms rebrightening (Moskvitin et al. GCN 33179) or 
plateau at 0.03 - 0.1 days and correlate with XRT LC 
(https://www.swift.ac.uk/xrt_curves/01149293/).