GCN Circular 3075

M. Perri, P. Giommi, M. Capalbi, F. Tamburelli (ASDC), P. Romano, D. 
Malesani (INAF-OAB), V. Mangano, G. Cusumano, T. Mineo (INAF-IASF/Palermo), 
D. N. Burrows, D. C. Morris, J. Kennea, M. Chester (PSU), K. L. Page, P. T. 
O'Brien (U. Leicester), L. Angelini, N. Gehrels (GSFC),  report on behalf 
of the Swift XRT team:

GRB 050306 was within the Swift Moon avoidance angle until mid-day on 07 
March 2005 (UT).  Swift slewed to the BAT position (Markwardt et al. 2005, 
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 ) at about 14:55 UT on 07 March 2005 as a Target of Opportunity and 
the XRT began observing it at 14:56:21 UT.  Based on the first three orbits 
of data (4218 s of data in Photon-Counting mode), we find two point sources 
in our field of view, one of which is within the 3 arcminute radius BAT 
error circle.  This X-ray source is not present in any X-ray catalog and 
its distance from the BAT position is ~105 arcsec.  The coordinates of this 
source are:

RA(J2000) = 18:49:14.0
Dec(J200) = -09:09:10.4

We estimate an uncertainty of about 6 arcseconds in this position.

We have only detected 12 photons from this source at this time and cannot 
yet comment on whether it is fading.  This source should be regarded as a 
possible X-ray afterglow candidate.  Further observations are in progress, 
and these may allow us to make a more positive identification at a later date.