GCN Circular 5077

P.A. Price (IfA, Hawaii), E. Berger (OCIW), D.B. Fox (Penn State), S.B.
Cenko and A. Rau (Caltech) report on behalf of a larger collaboration:

We have obtained a second epoch of imaging with the Gemini North
telescope of the XRT localisation of the short/hard GRB 060502B (GCN
#5063).  The observations commenced at 2006 May 4.43 UTC (1.7 days after
the GRB), and consisted of 5 x 300 sec exposures in r'.  These
observations have better seeing and depth than our first epoch
observation (2006 May 3.43 UTC, 0.7 days after the GRB; GCN #5071). 
Image subtraction does not reveal any variable sources within the XRT
error circle.  In particular, the galaxy ("G1") and source ("S1")
identified in our previous observations have not appreciably changed in
brightness.

These observations place a limiting magnitude of any optical afterglow
in our first epoch observation of approximately R ~ 24.3 mag, based on
assuming R=17.5 mag for USNO-B1 star 426-035230 (RA,Dec =
278.92572,52.61611).

We identify in the second epoch image an additional faint source ("S2")
at R ~ 25.8 mag in the error circle at approximate coordinates:

        18:35:45.86 +52:37:50.0 J2000

An image of the field is available at:

        http://www.ifa.hawaii.edu/~price/grb060502b.gif

Note that the magnitude of the faint galaxy ("G1") in GCN #5071 is
measured to be R ~ 23.8 mag in our first epoch observation, using the
above calibration, consistent with the observation of Halpern & Mirabal
(GCN #5072).  We apologise for any inconvenience this error may have
caused.

We thank the Gemini North observing team for obtaining these
observations.