GRB 240829B

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

"At 01:23:40.70 UT on 29 August 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240829B (trigger 746587425/240829058).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 204.6, Dec = 57.3  (J2000 degrees, equivalent to J2000 13h 38m, 57d 18'),
with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 22 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240829058/quicklook/glg_skymap_all_bn240829058.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240829058/quicklook/glg_healpix_all_bn240829058.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240829058/quicklook/glg_lc_medres34_bn240829058.gif"

M. Dafcikova, J. Ripa, M. Kolar (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. Duriskova, L. Szakszonova, 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.), T. 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 240829B (Fermi/GBM detection: GCN 37342
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 , INTEGRAL/SPI-ACS detection: trigger no. 10879) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; https://ui.adsabs.harvard.edu/abs/2023A%26A...677A..40P/abstract).

The detection was confirmed at the peak time 2024-08-29 01:23:45.2 UTC. The T90 duration measured by GRBAlpha is 9.5 s and the overall significance during T90 reaches 13 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB240829B_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.