GRB 230911B
GCN Circular 34653
Subject
GRB 230911B: Fermi GBM Final Real-time Localization
Date
2023-09-11T04:37:15Z (2 years ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 04:25:49 UT on 11 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230911B (trigger 716099154.520658 / 230911185).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 351.7, Dec = -55.0 (J2000 degrees, equivalent to J2000 23h 26m, -55d 00'), with a statistical uncertainty of 1.1 degrees.
The angle from the Fermi LAT boresight is 131.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911185/quicklook/glg_skymap_all_bn230911185.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/bn230911185/quicklook/glg_healpix_all_bn230911185.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911185/quicklook/glg_lc_medres34_bn230911185.gif
GCN Circular 34654
Subject
Fermi GRB 230911B: Global MASTER-Net observations report
Date
2023-09-11T05:45:51Z (2 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
legacy email
V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich
(Blagoveschensk Educational State University)
MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 230911B ( Fermi GBM team, GCN 34653) errorbox 928 sec after notice time and 961 sec after trigger time at 2023-09-11 04:41:51 UT, with upper limit up to 13.2 mag. The observations began at zenith distance = 24 deg. The sun altitude is -63.7 deg.
The galactic latitude b = -59 deg., longitude l = 326 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2268866
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
1052 | 2023-09-11 04:41:51 | MASTER-OAFA | (23h 25m 02.98s , -55d 03m 29.7s) | C | 180 | 12.1 |
1579 | 2023-09-11 04:50:38 | MASTER-OAFA | (23h 24m 58.92s , -55d 02m 04.7s) | C | 180 | 13.2 |
2059 | 2023-09-11 04:58:39 | MASTER-OAFA | (23h 25m 30.11s , -55d 04m 12.8s) | C | 180 | 13.1 |
2630 | 2023-09-11 05:08:09 | MASTER-OAFA | (23h 25m 03.23s , -55d 03m 59.3s) | C | 180 | 12.4 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 34660
Subject
GRB 230911B: correction to the KW GCN 34659
Date
2023-09-11T16:08:48Z (2 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
Via
legacy email
D. Frederiks, on behalf of the KW team,
the subject line of GCN 34659 contains a typo in the GRB name
and should read as "Konus-Wind detection of GRB 230911D"
We are sorry for the inconvenience.
GCN Circular 34664
Subject
GRB 230911B: GRBAlpha and VZLUSAT-2 joint detection
Date
2023-09-11T20:36:40Z (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.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Poon, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (U. Tokyo), K. Torigoe, Y. Uchida (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), T. Bozoki, G. Dalya, G. Friss, K. Kapas, J. Takatsy (Eotvos U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha and VZLUSAT-2/GRB payload collaborations
We report a joint detection of a long-duration GRB 230911B by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048) and the GRB detector on board of VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/). The event was also observed by Fermi/GBM (GCN 34653) and INTEGRAL/SPI-ACS at ~2023-09-11 04:25:51 UT.
The GRBAlpha detection was confirmed at the peak time 2023-09-11 04:25:51 UTC. The T90 duration is 15 s and the significance during T90 reaches 13 sigma.
The light curve obtained by GRBAlpha is available here:
https://grbalpha.konkoly.hu/static/share/GRB230911B_GCN.pdf
The VZLUSAT-2 detection was confirmed at the peak time 2023-09-11 04:25:50 UTC. The data acquisition was performed by the GRB detector unit no. 1. The T90 duration is 15 s and the significance during T90 reaches 9 sigma.
The light curves obtained by VZLUSAT-2 are available here:
https://vzlusat2.konkoly.hu/static/share/GRB230911B_GCN_VZLUSAT2.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.
All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/
The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.
GCN Circular 34677
Subject
GRB 230911B: AstroSat CZTI detection
Date
2023-09-12T13:29:01Z (2 years ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
Web form
P. K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of the long-duration GRB 230911B which was also detected by Fermi-GBM (Fermi GBM team, GCN Circ. 34653) along with GRBAlpha and VZLUSAT-2 (Dafcikova et al., GCN Circ. 34664).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2023-09-11 04:25:51.50 UTC. The measured peak count rate associated with the burst is 467 (+56, -35) counts/s above the background in the combined data of all quadrants, with a total of 3390 (+378, -416) counts. The local mean background count rate was 593 (+4, -4) counts/s. Using cumulative rates, we measure a T90 of 15 (+5, -3) s.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-09-11 04:25:51.83 UTC. The measured peak count rate associated with the burst is 790 (+75, -76) counts/s above the background in the combined data of all quadrants, with a total of 4781 (+532, -605) counts. The local mean background count rate was 1400 (+6, -7) counts/s. We measure a T90 of 14 (+7, -3) s from the cumulative Veto light curve.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb