TITLE: GCN CIRCULAR
NUMBER: 35266
SUBJECT: GRB 231205A: GECAM-B detection of a short burst
DATE: 23/12/05 03:48:51 GMT
FROM: tanwj(a)ihep.ac.cn
GRB 231205A: GECAM-B detection of a short burst
Wenjun Tan, Shaolin Xiong, report on behalf of the GECAM team:
GECAM-B was triggered in-flight by a short burst, GRB 231205A
at 2023-12-05T02:25:11.450 UTC(T0), which was also observed by
Fermi/GBM (Fermi/GBM team, GCN 35263).
According to the realtime alert data of GECAM-B, this burst consists
of one bright short pulse followed by weaker emission with a total
duration (T90) of about ~0.3 sec (30-1020 keV).
Using the automatic on-ground localization pipeline with the realtime alert data,
GECAM-B localized this burst to the following position (J2000):
Ra: 202.8 deg
Dec: 26.8 deg
Err: 6.1 deg (1-sigma, statistical only)
GECAM location is consistent with that of Fermi/GBM within the error.
The time-averaged spectrum of GECAM-B realtime data from about T0-0.05 s to T0 could be
adequately fit by a cut-off power-law with a fluence about 1.10E-6 erg/cm^2 in 20-1000 keV.
We note that these results are based on realtime alert data and thus very preliminary.
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B)
launched in Dec. 2020. As the third member of GECAM constellation,
GECAM-C was launched onboard SATech-01 experimental satellite in July 2022.
GECAM mission is funded by the Chinese Academy of Sciences (CAS).
View this GCN Circular online at https://gcn.nasa.gov/circulars/35266.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 35262
SUBJECT: LIGO/Virgo/KAGRA S231129ac: Upper limits from Swift/BAT-GUANO
DATE: 23/12/05 01:46:00 GMT
FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu>
Samuele Ronchini (PSU), Tyler Parsotan (NASA GSFC), Jamie A. Kennea (PSU), James DeLaunay (PSU), Gayathri Raman (PSU), Aaron Tohuvavohu (U Toronto) report:
Swift/BAT was observing 93.6% of the GW localization probability (Bilby.multiorder.fits) at merger time. A fraction 57% of the GW localization posterior is contained inside the BAT coded FoV.
The LVK 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.
Using the NITRATES analysis (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), we searched for emission on 8 timescales from 0.128s to 16.384s in the interval [-20,+20] seconds around the merger time. We find no evidence for a signal, and derive the following upper limits.
We quote the 5-sigma flux upper limits in the 15-350 keV band, weighted over the GW localization, for four spectral templates (soft, normal, and hard GRB-like templates described in [arXiv:1612.02395], and spectral shape from GRB170817A [arXiv:1710.05446]) and for four time bins.
In units of 10^-7 erg/s/cm^2:
time_bin (s) soft normal hard GRB170817
------------------------------------
0.256 7.22 5.29 4.76 5.82
1.024 4.07 2.98 2.68 3.28
4.096 2.78 2.03 1.83 2.24
16.38 2.33 1.71 1.53 1.88
The upper limits as function of sky position are plotted here, alongside the GW localization:
https://doi.org/10.5281/zenodo.10251985
The solid and dashed lines indicate the 90% and 50% GW contour levels, respectively.
The corresponding fits file can be found here:
https://doi.org/10.5281/zenodo.10251987
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/35262.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 35261
SUBJECT: IceCube-231202A: Upper limits from a search for additional neutrino events in IceCube
DATE: 23/12/05 00:39:33 GMT
FROM: Jessie Thwaites at IceCube/U Wisc-Madison <thwaites(a)wisc.edu>
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-231202A (https://gcn.nasa.gov/circulars/35255) in a time range of 1000 seconds centered on the alert event time (2023-12-02 17:00:04.090 UTC to 2023-12-02 17:16:44.090 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-231202A. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-231202A ranges from 1.4e-01 to 1.5e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 3e+02 GeV and 2e+05 GeV.
A subsequent search was performed including 2 days of data centered on the alert event time (2023-12-01 17:08:24.090 UTC to 2023-12-03 17:08:24.090 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-231202A is 1.6e-01 GeV cm^-2 in a 2 day time window.
The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu.
[1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)
View this GCN Circular online at https://gcn.nasa.gov/circulars/35261.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 35259
SUBJECT: GRB 231203A: Fermi GBM Observation
DATE: 23/12/04 22:31:12 GMT
FROM: rachel.hamburg(a)ijclab.in2p3.fr
R. Hamburg (CNRS/IN2P3) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 07:01:30.77 UT on 03 December 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231203A (trigger 723279695/231203293),
which was also detected by Swift/BAT-GUANO (DeLaunay et al. 2023, GCN 35257).
The Fermi Final Localization was reported in GCN 35252.
The angle from the Fermi LAT boresight is 59 degrees.
The GBM light curve consists of multiple peaks with a duration (T90)
of about 37 s (50-300 keV). The time-averaged spectrum
from T0-1.1 to T0+28.6 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.92 +/- 0.05 and the cutoff energy,
parameterized as Epeak, is 687 +/- 114 keV.
The spectrum is also well fit by a Band function with Epeak = 543 +/- 108,
alpha = -0.86 +/- 0.07, and beta = -2.10 +/- 0.30.
The event fluence (10-1000 keV) in this time interval is
(9.7 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.45 s in the 10-1000 keV band is 4.5 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
View this GCN Circular online at https://gcn.nasa.gov/circulars/35259.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 35257
SUBJECT: GRB 231203A: Swift/BAT-GUANO detection of a burst outside the coded FOV
DATE: 23/12/04 16:20:25 GMT
FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com>
James DeLaunay (PSU), Samuele Ronchini (PSU), Gayathri Raman (PSU), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:
Swift/BAT did not localize GRB 231203A onboard (T0: 2023-12-03T07:01:30.77 UTC, Fermi trig 723279723)
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), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 13.6 in a 2.048 s analysis time bin, starting at T0.
NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of 2.64.
See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.
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/35257.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…