TITLE: GCN CIRCULAR NUMBER: 23635 SUBJECT: IERCOO/ICSP optical observation of GRB 190106A DATE: 19/01/07 16:12:16 GMT FROM: Sandip K. Chakrabarti at ICSP IERCOO/ICSP optical observation of GRB 190106A Sandip K. Chakrabarti, Argha Sil, Shyam Sarkar, Ashim Sarkar, D. Bhowmick (Indian Centre for Space Physics) We observed GRB 190106A using 0.61m reflector of our observatory at Sitapur, West Bengal, India. The observation was with R, V, and B filters in a short interval at around 16:45UT on 6th January, 2019, i.e., about three hours after the BAT trigger (Sonbas et al. 2019; GCN 23615). Using two exposures each of 90s in R and in V, we obtained the magnitudes of 17.83+/-0.25 and 18.45 +/- 0.23 respectively. Using one 90s exposure in B, we obtained the magnitude of 18.81+/-0.39. Using triangulation, we obtained the location of the afterglow to be RA(J2000) = 01h 59m 31.17s, Dec(J2000) = +23d 50m 43.94s with two pixel error 0.46s. Three sigma method was used to estimate the magnitudes with a calibrator J01593557 +2348527 which is of V mag ~12.5. After 24 hours of the BAT trigger we do not detect the afterglow on 7th Jan. at 13:30UT. The details of images and other results will be in http:/csp.res.in.