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GRB 240331A

GCN Circular 35998

Subject

GRB 240331A: Fermi GBM Final Real-time Localization

Date

2024-04-01T00:05:53Z (a year ago)

From

Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

Via

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

At 23:55:19 UT on 31 Mar 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240331A (trigger 733622124.6772 / 240331997).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 31.4, Dec = 0.9 (J2000 degrees, equivalent to J2000 02h 05m, 0d 54'), with a statistical uncertainty of 5.8 degrees.

The angle from the Fermi LAT boresight is 62.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240331997/quicklook/glg_skymap_all_bn240331997.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/bn240331997/quicklook/glg_healpix_all_bn240331997.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240331997/quicklook/glg_lc_medres34_bn240331997.gif

GCN Circular 36000

Subject

GRB 240331A: AstroSat CZTI detection

Date

2024-04-01T10:25:36Z (a year ago)

From

Gaurav Waratkar at IIT Bombay <gauravwaratkar24@gmail.com>

Via

Web form

J. Joshi (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 a long-duration GRB 240331A which was also detected by the Fermi-GBM (Fermi-GBM Team, GCN Circ. 35998Loading...
 
 ).

The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2024-03-31 23:55:20.01 UTC. The measured peak count rate associated with the burst is 266 (+69, -53) counts/s above the background in the combined data of all quadrants, with a total of 1926 (+501, -548) counts. The local mean background count rate was 1448 (+8, -9) counts/s. We measure a T90 of 20 (+2, -6) 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

GCN Circular 36035

Subject

GRB 240331A: GRBAlpha detection

Date

2024-04-05T14:27:11Z (a year ago)

From

Marianna Dafčíková at Masaryk University <500025@mail.muni.cz>

Via

Web form

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 240331A (Fermi/GBM detection: GCN 35998Loading...
 
 ; AstroSat detection: GCN 36000Loading...
 
 ; INTEGRAL/SPI-ACS peak detection at 2024-03-31 ~23:55:20 UT) 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 2024-03-31 23:55:19.5 UTC. The T90 duration measured by GRBAlpha is 9.5 s and the overall significance during T90 reaches 6.8 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB240331A_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.