[vsnet-grb-info 10561] GRB 110426A: Swift/XRT non-detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11990
SUBJECT: GRB 110426A:  Swift/XRT non-detection
DATE:    11/05/03 13:51:45 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.krimm at nasa.gov>

H. A. Krimm (GSFC/USRA),V. D'Elia (ASDC) and G. Stratta (ASDC), report on
behalf of the Swift team:

Swift XRT and UVOT instruments observed the center of the error rectangle
for the MAXI-detected GRB 110426A (Nakahira et al, GCN Circ. 11980) on
two occasions.  The first observation was for 5 ks starting 7 ks after
the MAXI trigger.  In this observation four point sources were found.
One is consistent with a source in the Digitized Sky Survey and the other
three were  of <3-sigma significance.  The second observation, also 5 ks,
began 250 ks after then trigger.  In the second observation, the DSS source
was detected without having faded and two other weak sources were seen at
different locations.  Since there is no evidence for a fading source in
the XRT field of view, we conclude that we have not detected the afterglow
of GRB 110426A.
     However, we note that the reported 90% error box for GRB 110426A
(Nakahira et al, GCN Circ. 11980) is approximately eight times the size
of the XRT field of view. Therefore, it is likely that the true GRB
location is outside the observed field.