TITLE: GCN CIRCULAR NUMBER: 7163 SUBJECT: Early OT detection of XRF in NGC 2770 in Asiago frames DATE: 08/01/11 11:08:16 GMT FROM: Stefano Valenti at U di Ferrara,Italy S. Valenti, M. Turatto, H. Navasardyan, S. Benetti and E. Cappellaro report: The optical counterpart of the transient source in NGC 2270 (cfr. GCN 7159) was present on images of SN2007uy taken with the 1.8m telescope of the Asiago Observatory (+AFOSC) on Jan. 10.01 (10.5h after the Swift detection) and not visible (limit magnitude ~ 21) on Jan. 7.00. The transient was of mag ~ 19 in V, fainter than SN 2007uy by 3 and 2.8 magnitude in V and R, respectively. Following the report of J. Deng and Y. Zhu (GCN7160) that the transient was roughly 2 magnitudes fainter than SN2007uy on Jan. 10.76, in R band, it seems that the luminosity of the transient is rising rapidly, supporting the very fortunate possibility that Swift has observed, in real time, the explosion of a massive star. A image of the transient can be found at: http://www.eso.org/~svalenti/homepage/transient.jpg