GRB 230614B

The Fermi GBM team reports the detection of a likely LONG GRB

At 09:15:01 UT on 14 Jun 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230614B (trigger 708426906.627188 / 230614385).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 110.9, Dec = -61.9 (J2000 degrees, equivalent to J2000 07h 23m, -61d 53'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 15.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230614385/quicklook/glg_skymap_all_bn230614385.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/bn230614385/quicklook/glg_healpix_all_bn230614385.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230614385/quicklook/glg_lc_medres34_bn230614385.gif

James DeLaunay (U Alabama), Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Aaron Tohuvavohu (U Toronto) report: 

Swift/BAT did not localize GRB 230614B onboard (T0: 2023-06-14T09:15:01 UTC, Fermi/GBM trig 708426906, GCN 33958
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 ) 

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 with a sqrt(TS) of 16.18 in a 4.096 s analysis time bin. 
NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of 1.
The Fermi/GBM localization is consistent with being outside the BAT FOV (GCN 33958
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 ). 

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/

R. Hamburg (CNRS/IJCLab) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 09:15:01.63 UT on 14 June 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230614B (trigger 708426906 / 230614385),
which was also detected by Swift/BAT-GUANO (DeLaunay et al. 2023, GCN 33960
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 ).
The Fermi GBM Final Real-time Localization was reported in GCN 33958
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 .

The angle from the Fermi LAT boresight at the GBM trigger time is 15 degrees.

The GBM light curve consists of two main pulses with a duration (T90)
of about 15 s (50-300 keV). The time-averaged spectrum from T0-2.43 s 
to T0+18.05 s is best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.18 +/- 0.05 and
the cutoff energy, parameterized as Epeak, is 115 +/- 6 keV.

The event fluence (10-1000 keV) in this time interval is
(5.94 +/- 0.16)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.47 s in the 10-1000 keV band
is 10.3 +/- 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/"