TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4854 SUBJECT: GRB 060306: MAGNUM observations DATE: 06/03/06 23:02:26 GMT FROM: Paul Price at IfA,UH P.A. Price (IfA, Hawaii), T. Minezaki (IoA, Tokyo), L.L. Cowie, Y. Kakazu (IfA, Hawaii) and Y. Yoshii (IoA, Tokyo) report: We observed the XRT position (GCN 4850) of GRB 060306 (GCN 4848) with the robotic MAGNUM telescope + MIP dual-beam camera beginning at Mar 6.235 UTC (4.8 hours after the GRB). Images in the R, I and J bands show a source present within the XRT error circle, with R ~ 20.7 mag (based on USNO-A2.0 star at 02:44:19.08 -02:08:53.6 with R = 15.2 mag). However, this source is also present in the Digitised Sky Survey red plate at a similar flux level. The position of the source from the DSS plate is: 02:44:22.98 -02:08:51.1 J2000 Due to the limited time baseline, we cannot make a meaningful test for variability, and hence it is not yet clear whether or not this source is related to the GRB. If related, it would likely indicate that the GRB is at a relatively low redshift. No other sources are identified within the XRT error circle to R ~ 22 mag. Images of the field are shown at http://www.ifa.hawaii.edu/~price/magnum_grb060306.jpg Observers with CCD images of the source at a different epoch are invited to contact PAP to perform image subtraction. This message may be cited.