S. B. Cenko (GSFC), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC),
V. D'Elia (SSDC & INAF-OAR), J.D. Gropp (PSU), J. A. Kennea (PSU),
S. Laha (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
At 18:01:51 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 220611A (trigger=1110090). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 66.526d, -37.289d which is
RA(J2000) = 04h 26m 06s
Dec(J2000) = -37d 17' 20
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). Due to a telemetry gap, the BAT onboard
lightcurve is not immediately available. However, the triggering
algorithm found the source in an 8 second image, indicating a
The XRT began observing the field at 18:04:20.4 UT, 149.2 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 66.51418, -37.25899
which is equivalent to:
RA(J2000) = 04h 26m 03.40s
Dec(J2000) = -37d 15' 32.4"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 113 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
https://www.swift.ac.uk/sper. We cannot determine whether the source
is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 2.66
x 10^20 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 152 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. The list of sources is typically
complete to about 18 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.033.
We note that this source location is ~15 arcsec from the line of sight
to the galaxy MCG-06-10-007, which is described in Simbad
as an S0 galaxy, B=16.3, z~0.049, angular size 18"x16".
Burst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)