[vsnet-grb-info 1776] GRB 050714B: candidate afterglow does not fade

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3616
SUBJECT: GRB 050714B: candidate afterglow does not fade
DATE:    05/07/15 04:04:44 GMT
FROM:    Daniele Malesani at SISSA-ISAS,Trieste,Italy  <malesani at sissa.it>

S. Covino, P. D'Avanzo (INAF, OABr), D. Malesani (SISSA/ISAS), G.L. Israel, S. Piranomonte (INAF, OARm), G. Tagliaferri (INAF, OABr), G. Chincarini (Univ Milano-Bicocca), L. Stella (INAF, OARm), report:

Photometric analysis of our set of images of GRB 050714B (Levan et al., GCN 2613; Tueller et al., GCN 3615) taken with the VLT-FORS1 in the R band does not confirm the proposed identification of the object reported by Malesani et al. (GCN 3614) as the candidate optical afterglow.

The object shows constant brightness between Jul 14.984 UT and Jul 15.040 UT (from 56 to 137 minutes after the GRB, respectively) at about R = 21.7, taking as reference the USNO star U0675-11455984 with magnitude R = 15.3. A light curve for this object can be seen at the following URL:

  http://www.sissa.it/~malesani/GRB/050714B/candidate_lc.gif

We give below the refined coordinates for the candidate, adopting an astrometric solution based on the 2MASS catalog:

   alpha(J2000) = 11:18:47.71,  delta(J2000) = -15:32:51.6

The error is 0.2 arcsec.

We note that two fainter objects are present close to the edge of the XRT error circle

A: alpha(J2000) = 11:18:47.71,  delta(J2000) = -15:33:00.9
B: alpha(J2000) = 11:18:48.19,  delta(J2000) = -15:32:50.3

None of such objects is seen to vary by more than ~0.1 mag.

A finding chart can be found here:

  http://www.sissa.it/~malesani/GRB/050714B/GRB050714B_finder.jpg

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