GCN Circular 29907
Subject
Swift Trigger 1045571 is not a GRB
Date
2021-04-27T14:08:54Z (4 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
P. A. Evans (U Leicester), C. Gronwall (PSU), A. Y. Lien (GSFC/UMBC)
and K. L. Page (U Leicester) report on behalf of the Neil Gehrels
Swift Observatory Team:
At 06:56:48 UT on 2021-04-27, the Swift Burst Alert Telescope (BAT)
triggered and located on a marginal image peak due to noise fluctuation
when Swift entered the SAA (trigger=1045571). Swift slewed to the event.
The BAT on-board calculated location is
RA, Dec 263.109, 54.058 which is
RA(J2000) = 17h 32m 26s
Dec(J2000) = +54d 03' 29"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows the background
increase due to the SAA, but does not show any significant burst structure.
Using BAT ground data from T-61 to T+100 s, the image significance
decreases to 4.2 sigma, which is consistent with noise fluctuation.
No source was detected in ~700 s of Photon Counting mode data, starting 1.4 ks
after the trigger time, supporting the conclusion that this was not an
astrophysical event.
(Some information of this trigger was received at a delayed time due to
a TDRSS downlink gap.)