GRB 221115B
GCN Circular 32941
Subject
GRB 221115B: Swift/BAT-GUANO arcminute localization
Date
2022-11-15T23:40:37Z (3 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
James DeLaunay (UAlabama), Aaron Tohuvavohu (U Toronto), Gayathri
Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (GSFC/UMBC) report:
Swift/BAT did not localize GRB 221115B onboard (T0:
2022-11-15T09:46:15 UTC, CALET trig 1352540756).
The CALET notice, distributed in near real-time, triggered the Swift
Mission Operations Center operated Gamma-ray Urgent Archiver for Novel
Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst
Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from
[-50,+150] seconds around the time of the burst. All the requested
event mode data was delivered to the ground.
The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu,
arXiv:2111.01769), detects the burst in a 2.048 s analysis time bin
with a sqrt(TS) of 27.7.
The duration of the burst as seen by BAT is ~5 seconds.
A confident arcminute localization is found with DeltaLLHPeak of 49.
See Section 9.1 and Figure 17 in the NITRATES paper for brief
descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and
DeltaLLHOut.
The BAT position is
RA, Dec = 54.788, -16.701 deg which is
RA(J2000) = 03h 39m 09.16s
Dec(J2000) = -16d 42��� 03.5���
with an estimated uncertainty of 3 arcmin.
XRT and UVOT follow-up has been requested, but will be significantly
delayed due to operational constraints.
We encourage followup from other facilities.
GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/
GCN Circular 32943
Subject
GRB 221115B : MeerLICHT upper limits
Date
2022-11-17T11:07:15Z (3 years ago)
From
Simon de Wet at UCT <dwtsim002@myuct.ac.za>
S. de Wet (UCT), P.J. Groot (Radboud/UCT/SAAO) report on behalf of the
MeerLICHT consortium:
We observed the Swift/BAT-GUANO localisation of GRB 221115B (DeLaunay et
al., GCN 32941) with the 0.6m wide-field MeerLICHT optical telescope
situated in Sutherland, South Africa, obtaining 2x300s observations in the
q-band (roughly g+r) fully encompassing the 3' error box. Observations
began at 21:21:30 UT on 2022 November 16, 1.48 days post-trigger.
Employing our transient detection pipeline along with an archival reference
image, we detect no new transients within the GUANO error box down to a
5-sigma transient limiting magnitude of q > 20.80. Our new images had
full-frame 5-sigma limiting magnitudes of q = 22.10 and q = 22.18, while
our archival reference image had a limiting magnitude of q = 21.10. All
magnitudes are in the AB system.
MeerLICHT is built and run by a consortium consisting of Radboud
University, the University of Cape Town, the South African Astronomical
Observatory, the University of Oxford, the University of Manchester and the
University of Amsterdam.
GCN Circular 32945
Subject
GRB 221115B: LCOGT Optical Upper Limits
Date
2022-11-17T21:13:24Z (3 years ago)
From
Robert Strausbaugh at University of Minnesota <rstrausb@umn.edu>
R. Strausbaugh (University of Minnesota), A. Cucchiara (NASA) report on
behalf of a larger collaboration:
We observed the GRB 221115B (DeLaunay et al., GCN 32941) field with the
LCOGT 1-meter Sinistro instrument at the South African Astronomical
Observatory site, on November 16, from 19:40 to 20:08 (corresponding to
34.15 to 34.62 hours from the GRB trigger time) with the SDSS r and i
filters.
We performed a series of 3x300s exposures in each band. We do not detect
any fading uncatalogued sources in the BAT error region, in either band,
consistent with other optical upper limits (de Wet et al., GCN 32943).
The following upper limits are calculated using the Pan-STARRS catalog as
reference:
r > 22.4
i > 21.5
These magnitudes are not corrected for galactic extinction.
GCN Circular 32948
Subject
GRB 221115B: CALET Gamma-Ray Burst Monitor detection
Date
2022-11-18T19:06:45Z (3 years ago)
From
Yuta Kawakubo at Louisiana State U./CALET <kawakubo1@lsu.edu>
A. Yoshida, T. Sakamoto, S. Sugita (AGU), Y. Kawakubo (LSU),
K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka (ICRR),
S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena)
and the CALET collaboration:
The long GRB 221115B (Swift/BAT-GUANO arcminute localization: DeLaunay et al.,
GCN Circ. 32941) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 09:46:15.63 UTC on 15 November 2022
(http://cgbm.calet.jp/cgbm_trigger/flight/1352540756/index.html).
The burst signal was seen by all CGBM detectors.
The burst light curve shows two pulses.
The first faint pulse is around T-12 s, and the second main pulse starts
at T+0.0 sec, peaks at T+0.6, sec, and ends at T+2.4 sec.
The T90 and T50 durations measured by the SGM data are 2.1 +/- 0.2 sec
and 0.9 +/- 0.3 sec (40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1352540756/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.