TITLE: GCN CIRCULAR
NUMBER: 35416
SUBJECT: GRB 231222B: Fermi-LAT detection
DATE: 23/12/22 21:31:22 GMT
FROM: N. Di Lalla at Stanford University <niccolo.dilalla(a)stanford.edu>
N. Di Lalla (Stanford University), F. Longo (University and INFN, Trieste), A. Holzmann (DF, University of Buenos Aires, Argentina) report on behalf of the Fermi-LAT Collaboration:
On December 22, 2023 Fermi-LAT detected high-energy emission from GRB 231222B, which was also detected by Fermi-GBM (trigger 724922767 / 231222310).
The best LAT on-ground location is found to be
RA, Dec = 251.35, 19.55 (degrees, J2000)
with an error radius of 0.3 deg (90% containment, statistical error only). This was 19 deg from the LAT boresight at the time of the GBM trigger:
T0 = 07:26:02.19 UT.
The data from the Fermi-LAT show a significant increase in the event rate after the GBM trigger that is spatially correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval**0-600 s after the GBM trigger is (1.9 +/- 0.7) E-6**ph/cm2/s.
The estimated photon index above 100 MeV is -1.7 +/- 0.3. The highest-energy photon is a 3.6 GeV event which is observed 362 seconds after the GBM trigger.
A Swift ToO has been approved for this burst.
The Fermi-LAT point of contact for this burst is Makoto Arimoto (arimoto(a)se.kanazawa-u.ac.jp <mailto:arimoto@se.kanazawa-u.ac.jp>)
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35416.
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TITLE: GCN CIRCULAR
NUMBER: 35415
SUBJECT: GRB 231222A: Tiled Swift observations
DATE: 23/12/22 19:25:08 GMT
FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk>
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a series of observations, tiled on the sky, of the
Fermi/LAT GRB 231222A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00118
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35415.
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TITLE: GCN CIRCULAR
NUMBER: 35414
SUBJECT: IceCube-231211A: GRANDMA observations of PKS2047+098
DATE: 23/12/22 17:06:57 GMT
FROM: Thierry Pradier at IPHC/University of Strasbourg <tpradier(a)km3net.de>
M. Prouza, S. Karpov, M. Mašek (FZU), C. Andrade (UMN), S. Antier (OCA/Artemis), M. Coughlin (UMN), P.A. Duverne (APC), P. Hello (IJCLAB), I. Tosta e Melo (UniCT-DFA), T. Pradier (Unistra/IPHC), D. Turpin (CEA),
report on behalf of the GRANDMA collaboration:
We observed the field of PKS2047+098 after the detection of 2 IceCube high-energy neutrino candidates (GCN 35328, 35332), and the report of an increased gamma-ray activity for this Blazar by Fermi-LAT (GCN 35329). Master-Net reported upper limits for the considered errorbox soon after the IceCube alert (GCN 35321).
Imaging with FRAM-CTA-N telescope of the GRANDMA collaboration in the r- and v-bands, we obtained R > 18.3 and V > 18.6 (5 sigma) on 2023-12-14T20:11:42 and 2023-12-14T20:13:20 with 19x90s exposure.
Followup will continue in the forthcoming weeks.
GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518).
View this GCN Circular online at https://gcn.nasa.gov/circulars/35414.
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TITLE: GCN CIRCULAR
NUMBER: 35413
SUBJECT: GRID detection of GRB 231215A
DATE: 23/12/22 09:12:33 GMT
FROM: GRID Student Team at Tsinghua University <grid(a)tsinghua.edu.cn>
Chenyu Wang, Zirui Yang and Longhao Li report on behalf of the GRID Collaboration:
GRID-04 reports the detection of the long-duration GRB 231215A, which was also detected by Swift/BAT, AstroSat CZTI, AGILE, Fermi/GBM, Konus-Wind and GRBAlpha(GCN Circular 35343, 35352, 35361, 35369, 35377 and 35380).
The event was triggered with GRID on 2023-12-15 at 09:47:18.5 UTC. The measured burst duration (T90) in the 30-2000 keV range is approximately 17.0 ± 1.5 seconds.
The time-averaged spectrum of GRID-04 realtime data from T+0 to T+18 sec is best fit by a cutoff power-law model. The index of the time-averaged spectrum is -0.576(-0.108,+0.114) with a fluence in the 10-1000 keV band is about 5.2488E-05 erg/cm2. All the quoted errors are at the 1-sigma confidence level.
The GRID light curve of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB231215A/GRID_231…. The GRID spectrum of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB231215A/GRID_231….
GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35413.
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TITLE: GCN CIRCULAR
NUMBER: 35411
SUBJECT: GRB 231220A: Swift-XRT follow-up observations
DATE: 23/12/21 15:25:45 GMT
FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk>
C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB), S. Dichiara (PSU), J.A.
Kennea (PSU), A. Tohuvavohu (U. Toronto), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), R. Brivio (INAF-OAB) and P.A. Evans (U.
Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the GUANO-detected
burst GRB 231220A, collecting 3.6 ks of Photon Counting (PC) mode data
between T0+27.0 ks and T0+39.5 ks.
No candidate counterpart was detected, with an upper limit of
2.2×10-3 ct s-1 at the best BAT position (GCN 35409).
One uncatalogued X-ray source was flagged as spurious
after manual inspection.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021638.
This circular is an official product of the Swift-XRT team.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35411.
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TITLE: GCN CIRCULAR
NUMBER: 35410
SUBJECT: GRB 231220A: Swift ToO observations
DATE: 23/12/20 23:38:36 GMT
FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk>
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the GUANO GRB 231220A.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021638
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the GUANO event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a
GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35410.
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TITLE: GCN CIRCULAR
NUMBER: 35409
SUBJECT: GRB 231220A: Swift/BAT-GUANO arcminute localization of a long burst
DATE: 23/12/20 22:09:23 GMT
FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu>
Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:
Swift/BAT did not localize GRB 231220A onboard (T0: 2023-12-20T16:10:17.4 UTC, Fermi/GBM GCN 35407).
The Fermi 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 2022, ApJ, 941, 169), detects the burst in a 4.096 s analysis time bin with a sqrt(TS) of 28.32, starting at T0 - 1.02 s.
An arcminute localization is found with DeltaLLHOut of 48.29 and a DeltaLLHPeak of 49.13.
See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.
The BAT position is
RA, Dec = 27.321, 77.897 deg which is
RA(J2000) = 01h 49m 17.04s
Dec(J2000) = +77d 53′ 49.2″
with an estimated uncertainty of 5 arcmin radius.
XRT and UVOT follow-up has been requested.
Results of follow-up observations will be reported in future circulars.
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/
View this GCN Circular online at https://gcn.nasa.gov/circulars/35409.
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