TITLE: GCN CIRCULAR NUMBER: 7206 SUBJECT: X-ray transient in NGC 2770: RTT150 optical observations DATE: 08/01/23 14:55:26 GMT FROM: Rodion Burenin at IKI, Moscow I. Bikmaev, A. Galeev, N. Sakhibullin (KSU/AST) R. Burenin, M. Pavlinsky, R. Sunyaev (IKI), I. Khamitov, Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.) report: The optical counterpart to X-ray transient in NGC 2770, SN2008D (GCN Rep. 110.1, GCN Circ. 7160, 7161) was observed also with Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National Observatory, Turkey) during the first two nights after the XRF. Series of BVRI direct images and low resolution spectra (during the second night) were taken. The object shows no variability during the few hours of observations in every nignt at the level >~ 0.05m, but we detect the decline of the OT in all filters betwen two nights. Assuming R=17.3 and B=17.7 magnitudes for USNO-A2.0 1200-06240802 star (as it was done in GCN's 7162 and 7187), we estimate the following magnitudes for the transient: Time, UT t-t0,days mag Jan 11.03 0.46 R = 18.06 Jan 11.14 0.57 B = 18.72 Jan 12.11 1.55 R = 18.15 Jan 12.12 1.55 B = 18.98 However, these measurements are preliminary, more accurate subtraction of the galaxy is to be done. A low resolution spectrum was obtained, using TFOSC spectrometer. We take 3x1200s exposures, centered at Jan 12.00 UT. The spectrum has resolution about 15~A, covering 3900 to 9000~A. Strong H_alpha and other narrow emission lines are detected in the galaxy near the object, so that it was difficult to correctly subtract background near these lines. Hovewer, we believe, that the overall shape of our spectrum is correct. We definitely see much less amount of supernova signatures as compared to Blondin et al. (GCN 7173), in agreement with Soderberg et al. (GCN 7165) and Thorstensen (ATEL #1358). The finding chart and the plot of our spectrum can be found at: http://hea.iki.rssi.ru/grb/080110-SN2008D/indexeng.html