GRB 230707B
GCN Circular 34165
Subject
GRB 230707B: Fermi GBM Final Real-time Localization
Date
2023-07-07T18:56:58Z (2 years ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
The Fermi GBM team reports the detection of a likely LONG GRB
At 18:46:20 UT on 7 Jul 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230707B (trigger 710448385.289496 / 230707782).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 28.5, Dec = -41.3 (J2000 degrees, equivalent to J2000 01h 53m, -41d 17'), with a statistical uncertainty of 2.2 degrees.
The angle from the Fermi LAT boresight is 83.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230707782/quicklook/glg_skymap_all_bn230707782.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230707782/quicklook/glg_healpix_all_bn230707782.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230707782/quicklook/glg_lc_medres34_bn230707782.gif
GCN Circular 34169
Subject
GRB 230707B: Swift/BAT-GUANO detection of a burst outside the coded FOV
Date
2023-07-08T12:27:24Z (2 years ago)
From
Jimmy DeLaunay at University of Alabama <delauj2@gmail.com>
James DeLaunay (U Alabama), Aaron Tohuvavohu (U Toronto), Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:
Swift/BAT did not localize GRB 230707B onboard (T0: 2023-07-07T18:46:20.29 UTC, Fermi trig 710120768, CALET trig 1372790743, INTEGRAL trig 10313)
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 12.0 in a 16.384 s analysis time bin, starting at T0.
The burst is ~100 s in duration as seen by BAT.
NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of -7 and are consistent with Fermi GBM's localization (GCN 34165).
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/
GCN Circular 34189
Subject
GRB 230707B: CALET Gamma-Ray Burst Monitor detection
Date
2023-07-10T07:10:03Z (2 years ago)
From
Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>
S. Torii (Waseda U), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka (ICRR), 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 230707B (Fermi GBM Final Real-time Localization:
Fermi GBM team, GCN Circ. 34165; Swift/BAT-GUANO detection:
DeLaunay et al., GCN Circ. 34169) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 18:46:18.95 UTC on 7 July 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1372790743/index.html).
The burst signal was seen by all CGBM detectors.
The burst light curve shows a multi-peaked structure that starts
at T+1.0 sec, peaks at T+82.1 sec, and ends at T+108.1 sec.
The T90 and T50 durations measured by the SGM data are 94.6 +/- 1.6 sec
and 52.1 +/- 1.2 sec (40-1000 keV), respectively.
The ground-processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1372790743/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.
GCN Circular 34197
Subject
GRB 230707B: Fermi GBM Observation
Date
2023-07-10T20:00:51Z (2 years ago)
From
sumanbala2210@gmail.com
S. Bala (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 18:46:20.29 UT on 07 July 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230707B (trigger 710448385/230707782).
which was also detected by Swift/BAT-GUANO (James DeLaunay et al. 2023, GCN 34169)
and CALET GBM (S. Torii et al. 2023, GCN 34189). The Fermi GBM Final Real-time Localization
was reported at GCN 34165.
The angle from the Fermi LAT boresight is 83 degrees.
The GBM light curve is long and consists of many peaks with a duration (T90)
of 99.6 s (50-300 keV). The time-averaged spectrum
from T0-2.3 to T0+117.5 s is best fit by
a Band function with Epeak = 143 +/- 5 keV,
alpha = -0.63 +/- 0.04, and beta = -2.15 +/- 0.05.
The event fluence (10-1000 keV) in this time interval is
(5.4 +/- 0.1)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+80 s in the 10-1000 keV band is 5.3 +/- 0.3 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/"