GCN Circular 11820
Subject
GRB 110319B Swift-XRT afterglow confirmation
Event
Date
2011-03-24T16:31:02Z (15 years ago)
From
Boris Sbarufatti at INAF-OAB/IASFPA <boris.sbarufatti@brera.inaf.it>
B. Sbarufatti (INAF-OAB/IASFPA) reports on behalf of the Swift-XRT team:
Swift performed a second target of opportunity observation of
GRB 110319B on March 23, 2011.
The XRT began observing the field at 2011-03-23 17:57:33 UT, that is
T+340 ks ( 3.9 days) (Cummings, GCN Circ. 11813).
Using 4.9 ks of Photon Counting mode data we find that the source
reported previously (Sbarufatti, GCN Circ. 11814) has faded down to
a 3-sigma upper limit of 0.002 counts/s.
Assuming a power law decay starting from the first source detection
the upper limit is consistent with a decay index steeper than
alpha = 0.6.
The fading nature of the source confirms its afterglow origin.
This circular is an official product of the Swift-XRT team.