GRB 231019A

C.C. Cheung, M. Kerr, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:
 
The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 231019A, which was also detected by Fermi/GBM, INTEGRAL/SPI-ACS, and VZLUSAT-2 (GCN 34842
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 , 34866
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 ).
 
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-10-19 17:09:56.896 with a duration of 2.1 s and a total significance of about 12.3 sigma.  The light curve comprises a single peak.
 
Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=4.3 and a cutoff energy ("Epeak") of 130 keV.  The modeled 10-10000 keV fluence is 2.4e-07 erg/cm^2.
 
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
 
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.
 
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
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[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006
 
Distribution Statement A: Approved for public release.  Distribution is unlimited.

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N. Werner  (Masaryk U.), M. Ohno (Hiroshima U.),  L. Meszaros, B. Csak (Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, 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 (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the VZLUSAT-2/GRB payload collaboration.

The long duration GRB 231019A (Fermi/GBM detection: GCN 34842
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 ; INTEGRAL/SPI-ACS peak detection at 2023-10-19 ~17:09:58 UT) was detected by the GRB detectors on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).

The data acquisition was performed by the GRB detector units no. 0 and no. 1. The detection was confirmed at the peak time 2023-10-19 17:10:01 UTC. The T90 duration is 10 s (6 s) and the significance during T90 reaches 5.5 sigma (4.6 sigma) for detector unit no. 0 (no. 1).

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB231019A_GCN_VZLUSAT2.pdf

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.

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-Amur robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the Fermi GRB 231019A ( Fermi GBM team, GCN 34842
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 ) errorbox  816 sec after notice time and 850 sec after trigger time at 2023-10-19 17:24:09 UT, with upper limit up to  17.5 mag. The observations began at zenith distance = 46 deg. The sun  altitude  is -42.0 deg. 

The galactic latitude b = -12 deg., longitude l = 103 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2288694

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

     881 | 2023-10-19 17:24:09 |         MASTER-Amur | (22h 54m 16.71s , +46d 46m 10.5s) |   C |    60 | 17.4 |        
     961 | 2023-10-19 17:25:28 |         MASTER-Amur | (23h 05m 59.53s , +46d 44m 56.9s) |   C |    60 | 17.5 |        
    1040 | 2023-10-19 17:26:48 |         MASTER-Amur | (22h 59m 27.09s , +48d 37m 55.9s) |   C |    60 | 17.5 |        
    1120 | 2023-10-19 17:28:08 |         MASTER-Amur | (23h 11m 28.93s , +48d 39m 20.4s) |   C |    60 | 17.4 |        
    1200 | 2023-10-19 17:29:28 |         MASTER-Amur | (22h 36m 34.03s , +48d 40m 14.4s) |   C |    60 | 17.1 |        
    1279 | 2023-10-19 17:30:47 |         MASTER-Amur | (22h 48m 32.17s , +48d 39m 03.7s) |   C |    60 | 17.4 |        
    1370 | 2023-10-19 17:32:18 |         MASTER-Amur | (22h 42m 41.86s , +50d 33m 03.9s) |   C |    60 | 17.2 |        
    1450 | 2023-10-19 17:33:38 |         MASTER-Amur | (22h 55m 09.57s , +50d 31m 51.8s) |   C |    60 | 17.4 |        
    1530 | 2023-10-19 17:34:58 |         MASTER-Amur | (22h 54m 23.63s , +46d 44m 22.5s) |   C |    60 | 17.1 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.

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

At 17:09:58 UT on 19 Oct 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231019A (trigger 719428203.333452 / 231019715).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 343.1, Dec = 45.7 (J2000 degrees, equivalent to J2000 22h 52m, 45d 42'), with a statistical uncertainty of 7.2 degrees.

The angle from the Fermi LAT boresight is 92.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231019715/quicklook/glg_skymap_all_bn231019715.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/bn231019715/quicklook/glg_healpix_all_bn231019715.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231019715/quicklook/glg_lc_medres34_bn231019715.gif