[vsnet-grb-info 2568] GRB 051227: R-band object in the XRT error circle

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4404
SUBJECT: GRB 051227: R-band object in the XRT error circle
DATE:    05/12/28 05:39:12 GMT
FROM:    Daniele Malesani at SISSA-ISAS,Trieste,Italy  <malesani at sissa.it>

D. Malesani (SISSA), S. Piranomonte, L.A. Antonelli (INAF/OAR), E. 
Depagne, C. Lidman, C. Melo (ESO), S. Campana, S. Covino, G. Tagliaferri 
(INAF/OABr), G. Chincarini (Univ. Milano-Bicocca), M. Della Valle 
(INAF/OAA), F. Fiore, and L. Stella (INAF/OARm), report on behalf of the 
MISTICI collaboration:

We observed the field of the hard (and possibly short) GRB 051227 
(Barbier et al., GCN 4397; Barthelmy et al., GCN 4401; Sakamoto et al., 
GCN 4403) using the ESO VLT-UT2 (Kueyen) equipped with the FORS1 
instrument. Observations started on 2005 Dec 28, 04:22 UT (~10.3 h after 
the GRB), in the R band. Observations were conducted at high airmass and 
moderate seeing (1.5").

Coadding three 5-min images, we detect inside the revised XRT error 
circle (Beardmore et al., GCN 4402) one single, faint source, at the 
coordinates (J2000):

  alpha = 08:20:58.14
  delta = +31:55:31.7

The astrometric error is about 0.5". This object is not seen in the 
r-band SDSS images provided by Cool et al. (GCN 4399). However, it is 
significantly fainter than the limit of these images. We propose this 
object as a candidate afterglow or host for GRB 051227.

We also note a further, fainter object slightly outside the XRT error 
circle, at the coordinates:
  alpha = 08:20:57.54
  delta = +31:55:32.47

We acknowledge the excellent support from the ESO staff.