GRB 230911D
GCN Circular 34656
Subject
GRB 230911D: Fermi GBM Final Localization
Date
2023-09-11T09:35:37Z (2 years ago)
From
rachel.hamburg@ijclab.in2p3.fr
Via
Web form
The Fermi GBM team reports the detection of a likely long GRB.
At 07:53:09.73 UT on 11 September 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230911D (trigger 716111594 / 230911329).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 154.9, Dec = -20.9 (J2000 degrees, equivalent to J2000 +10h 19m, -20d 55'), with a statistical uncertainty of 1.0 degree.
The angle from the Fermi LAT boresight is 67 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911329/quicklook/glg_skymap_all_bn230911329.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/bn230911329/quicklook/glg_healpix_all_bn230911329.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911329/quicklook/glg_lc_medres34_bn230911329.gif
GCN Circular 34657
Subject
GRB 230911D: BALROG localization (Fermi Trigger 716111594/ GRB 230911329)
Date
2023-09-11T10:08:57Z (2 years ago)
From
Jochen Greiner at MPE <jcgrog@mpe.mpg.de>
Via
email
B. Biltzinger, T. Preis, J. Burgess & J. Greiner (all MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
at 07:53:09 on 11 Sept. 2023 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).
The best-fit position (1 sigma statistical errors) is:
RA(2000.0) = 148.9+/-0.2 deg
Decl.(2000.0) = -23.4+/-0.7 deg
We estimate an additional systematic error of 1 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB230911329/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB230911329/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB230911329/json
GCN Circular 34668
Subject
GRB 230911D: Fermi-LAT detection
Date
2023-09-11T22:12:40Z (2 years ago)
From
N. Di Lalla at Stanford University <niccolo.dilalla@stanford.edu>
Via
email
F. Longo (University and INFN, Trieste), D. Kocevski (NASA/MSFC), N. Omodei (Stanford University), N. Di Lalla (Stanford University) report on behalf of the Fermi-LAT Collaboration:
On September 11, 2023 Fermi-LAT detected high-energy emission from GRB 230911D, which was also detected by Fermi-GBM (trigger 716111594 / 230911329, GCN 34656) and Konus-Wind (GCN 34659).
The best LAT on-ground location is found to be
RA, Dec = 151.9, -26.0 (degrees, J2000)
with an error radius of 0.3 deg (90% containment, statistical error only). This was 73 deg from the LAT boresight at the time of the GBM trigger:
T0 = 07:53:09.73 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 0-1000 s after the GBM trigger is (2.3 +/- 0.8)E-5 ph/cm2/s.
The estimated photon index above 100 MeV is -1.9 +/- 0.2. The highest-energy photon is a 4.6 GeV event which is observed 154 seconds after the GBM trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is Makoto Arimoto (arimoto@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.
GCN Circular 34669
Subject
IPN triangulation of GRB 230911D (long)
Date
2023-09-11T22:32:48Z (2 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
Via
legacy email
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,
D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,
E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:
The bright, short-duration GRB 230911D
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 34656;
BALROG localization: Biltzinger et al., GCN Circ. 34657;
Konus-Wind detection: Frederiks et al., GCN Circ. 34659;
Fermi-LAT detection: Longo et al., GCN Circ. 34668)
was detected by Fermi (GBM trigger 716111594), INTEGRAL (SPI-ACS),
Konus-Wind, Swift (BAT), and Mars-Odyssey (HEND)
at about 28389 s UT (07:53:09).
The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
151.360 (10h 05m 26s) -25.633 (-25d 38' 00")
Corners:
151.696 (10h 06m 47s) -26.192 (-26d 11' 31")
151.638 (10h 06m 33s) -26.200 (-26d 12' 01")
151.036 (10h 04m 09s) -25.072 (-25d 04' 18")
151.093 (10h 04m 22s) -25.064 (-25d 03' 51")
---------------------------------------------
The error box area is 226 sq. arcmin, and its maximum
dimension is 1.3 deg (the minimum one is 3 arcmin).
The Sun distance was 35 deg.
The IPN localization is consistent with, but reduces the area of,
the Fermi-LAT localization (GCN 34668).
This localization may be improved.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230911_T28387/IPN
GCN Circular 34670
Subject
GRB 230911D: Fermi GBM observation
Date
2023-09-11T22:45:14Z (2 years ago)
From
Lorenzo Scotton at UAH <lscottongcn@outlook.com>
Via
Web form
L. Scotton (UAH), R. Hamburg (CNRS/IJCLab), and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 07:53:09.72 UT on 11 September 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230911D (trigger 716111594 / 230911329),
which was also detected by the Fermi LAT (F. Longo et al. 2023, GCN 34668)
and Konus-Wind (D. Frederiks et al. 2023, GCN 34659).
The Fermi GBM Final Localization (GCN 34656) is consistent with the Fermi LAT position.
The angle from the Fermi LAT boresight at the GBM trigger time is 72 degrees.
The GBM light curve consists of multiple peaks
with a duration (T90) of about 45.6 s (50-300 keV).
The time-averaged spectrum from T0-4.4 s to T0+77.6 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.00 +/- 0.01 and
the cutoff energy, parameterized as Epeak, is 429.9 +/- 7.8 keV
The event fluence (10-1000 keV) in this time interval is
(1.214 +/- 0.007)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+16.1 s in the 10-1000 keV band
is 24.8 +/- 0.3 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 420.6 +/- 9.0 keV, alpha = -1.00 +/- 0.01 and beta = -3.02 +/- 0.25.
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/"
GCN Circular 34678
Subject
GRB 230911D: NuSTAR Detection of Prompt Emission
Date
2023-09-12T17:57:47Z (2 years ago)
From
Brian Grefenstette at Caltech/NuSTAR <bwgref@srl.caltech.edu>
Via
Web form
B. Grefenstette and A. Jaodand (Caltech) report on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group:
The NuSTAR SINGS working group reports the detection of prompt emission from the Long GRB 230911D in both the NuSTAR CsI anti-coincidence shields and in the CdZnTe hard X-ray imagers. This GRB was identified through a blind search using the CsI shield rates. Details of the search algorithm will be described in a future paper.
The NuSTAR GRB search algorithm triggered at 2023-09-11T07:53:11, which is roughly 1.25-s after the Fermi detection (Hamburg et al., GCN Circ. 34656). When we consider the 1-s resolution of the shield data combined with the smoothing of the search algorithm, we consider the NuSTAR GRB time to be consistent with the time reported by Fermi.
Using the GRB localization (Greiner, et al., GCN Circ. 34657) and the NuSTAR trigger time, we estimate that the GRB was above the Earth's horizon as seen by NuSTAR and roughly 83-degrees off-axis from the NuSTAR boresight at the time of the GRB (e.g., through the side of the instrument).
The CsI data are recorded at 1 Hz and show a broad burst with multiple peaks. 1-sec count rates peaked at ~4,000 counts per second in both the FPMA and FPMB shield units. Typical background rates are ~1,000 counts per second.
The burst was also coincidentally detected in both CdZnTe detectors, with peak count rates of ~30 counts above 100 keV in 5-s time bins.
Flux calibration from the CdZnTe detectors for far off-axis is currently not possible since the X-rays observed by the CdZnTe detectors this far off-axis likely have multiple scatters in the instrument before being recorded by the X-ray detectors. Work on understanding the response and converting measured rates to incident fluxes is on-going.
The automated light curve report for this GRB can be found here:
https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2023/230911D/
Information on NuSTAR SINGS can be found here:
https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/
NuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington.
GCN Circular 34712
Subject
GRB 230911D: GRBAlpha detection
Date
2023-09-16T16:00:54Z (2 years ago)
From
Marianna Dafčíková at Masaryk University <500025@mail.muni.cz>
Via
Web form
M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), yyT. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.
The long-duration GRB 230911D (Fermi/GBM detection: GCN 34656; Fermi/LAT detection: GCN 34668; Konus/Wind detection: GCN 34659; NuSTAR detection: GCN 34678; INTEGRAL/SPI-ACS peak detection at 2023-09-11 ~07:53:25 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).
The detection was confirmed at the peak time 2023-09-11 07:53:26 UTC. The T90 duration measured by GRBAlpha is 45 s and the overall significance during T90 reaches 56 sigma.
The light curve obtained by GRBAlpha is available here:
https://grbalpha.konkoly.hu/static/share/GRB230911D_GCN.pdf
All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume.