TITLE:   GCN CIRCULAR
NUMBER:  33187
SUBJECT: GRB 230116D: SAO RAS redshift
DATE:    23/01/17 15:29:14 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Moskvitin (SAO RAS), A. Pozanenko (IKI),  A. Moiseev (SAO RAS), D. 
Oparin  (SAO RAS), S. Belkin (IKI, HSE) report on behalf of larger 
collaboration:

We observed the optical afterglow (Zhu et al., GCN 33177; Nazarov  et 
al., GCN 33178; Moskvitin et al., GCN 33179; Swain et al., GCN 33182) 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. Spectroscopic observations consists of 10x600 s exposures with 
  940@600 grizm.

We detect a sharp break at 5850 AA and afterglow continuum up to 7200 
AA. We interpret the sharp break due to H I. Over the continuum we 
identified multiple absorption features, which we interpret as due to S 
II, Si II, O I, C II, Si IV at a common redshift of z = 3.81.