TITLE: GCN CIRCULAR NUMBER: 6410 SUBJECT: GRB 070509: objects inside XRT error circle DATE: 07/05/16 22:08:24 GMT FROM: Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center D. Malesani, C.C. Thoene (DARK), A. Williams (Perth Obs.), J.P.U. Fynbo (DARK), A.O. Jaunsen (Univ. Oslo) and P.M. Vreeswijk (ESO) report on behalf of a larger collaboration: We observed the field of GRB 070509 (Vetere et al., GCN 6394) with the ESO VLT UT2 equipped with the FORS1 instrument. Short BVRI observations were carried out between 2007 May 9.144 and 9.155 UT (starting 0.65 hr after the GRB). We detect three objects close to the XRT position, at the following coordinates (J2000, 0.5" error): A: RA = 15:51:49.29 Dec = -78:39:01.7 R = 23.48 +- 0.24 B: RA = 15:51:50.37 Dec = -78:39:06.4 R = 23.52 +- 0.25 C: RA = 15:51:50.91 Dec = -78:39:10.2 R = 22.71 +- 0.16 Objects A and B are inside the XRT error circle as reported by Vetere et al. (GCN 6400), while objects B and C are inside the XRT error circle as provided in Nat Butler's web page (revision 1.2, http://astro.berkeley.edu/~nat/swift/xrt_pos.html). Objects A and C are extended. Magnitudes are computed at the mean time 9.149 UT (0.78 hr after the GRB) and are calibrated against the USNO-B1 catalog. The 3-sigma limit is R = 23.8. A finding chart of the field can be seen here: http://www.astro.ku.dk/~malesani/GRB/070509/finder_VLT.jpg Further R-band observations were carried out with the 1.54m Danish telescope located in La Silla (Chile) and equipped with DFOSC on 2007 May 9.141 (4500 s) and May 13.134 UT (3000 s). Object C is marginally detected in both images, while objects A and B are below the detection limit. At this stage, we cannot claim association between the GRB and any of the above mentioned objects. We acknowledge excellent support from the observing staff in Paranal, in particular Alain Smette and Gael James. CT acknowledges Pisco and Bacardi support from the GROND staff at La Silla.