GCN Circular 3362

V. La Parola, V. Mangano (INAF-IASF/Palermo), J. A. Kennea, D. N. Burrows 
(PSU), T. Sakamoto (GSFC), C. P. Hurkett (U. Leicester) and N. Gehrels 
(GSFC) report on behalf of the Swift XRT team:

The Swift BAT instrument detected a GRB at 22:35:54 UT on 16th April 2005
(Hullinger et al., GCN 3279
Not found
 
 
). Due to the close proximity of this burst to
the moon, the observatory did not execute an automated slew at that time.
This burst became visible to Swift Narrow Field Instruments at 12:48:00 UT
on 20th April 2005 (i.e. 86.3 hours after the trigger), and was observed by
Swift-XRT as a pre-planned target on 20th April, 22nd April, and 1st May
2005.  Five uncataloged sources are detected within the BAT error
circle(Sato et al., GCN Circ 3284), but none of them is fading. The source
previously indicated as a tentative afterglow candidate in GCN 3295
Not found
 
 
 (Kennea
et al.) is stable within errors.  Thus we cannot identify any afterglow for
this GRB. We estimate 3 sigma upper limits of 2E-14, 1.7E-14, and 1.5E-14
erg/cm2/s for the flux of the GRB afterglow in the first, second and third
observations, respectively.