GRB 240718A
GCN Circular 36898
Subject
GRB 240718A: Fermi GBM Final Real-time Localization
Date
2024-07-18T06:39:25Z (10 months 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 06:29:00 UT on 18 Jul 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240718A (trigger 742976945.434234 / 240718270).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 252.9, Dec = -27.3 (J2000 degrees, equivalent to J2000 16h 51m, -27d 18'), with a statistical uncertainty of 1.3 degrees.
The angle from the Fermi LAT boresight is 50.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240718270/quicklook/glg_skymap_all_bn240718270.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/bn240718270/quicklook/glg_healpix_all_bn240718270.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240718270/quicklook/glg_lc_medres34_bn240718270.gif
GCN Circular 36899
Subject
GRB 240718A: BALROG localization (Fermi Trigger 742976945 / GRB 240718270)
Date
2024-07-18T07:15:28Z (10 months ago)
From
Jochen Greiner at MPE <jcgrog@mpe.mpg.de>
Via
email
T. Preis, B. Biltzinger, J. Burgess & J. Greiner (all MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
742976945 at 06:29:00 on 18 July 2024 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 is:
RA(2000.0) = 250.8 deg
Decl.(2000.0) = -26.9 deg
The 1 sigma statistical error radius is 1.9 deg.
We estimate an additional systematic error of 2 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB240718270/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB240718270/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB240718270/json
GCN Circular 36900
Subject
GRB 240718A: SVOM/GRM observation
Date
2024-07-18T11:47:03Z (10 months ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Yan-Ting Zhang, Chen-Wei Wang, Yong-Wei Dong, Jiang-Tao Liu, Min Gao, Hao-Xuan Guo, Jiang He, Yue Huang, Lu Li, Yong-Ye Li, Hong-Wei Liu, Xin Liu, Hao-Li Shi, Li-Ming Song, Jian-Chao Sun, You-Li Tuo, Hao-Xi Wang, Jin Wang, Jin-Zhou Wang, Ping Wang, Rui-Jie Wang, Yu-Xi Wang, Bo-Bing Wu, Shao-Lin Xiong, Jian-Ying Ye, Yi-Tao Yin, Wen-Hui Yu, Fan Zhang, Li Zhang, Peng Zhang, Shuang-Nan Zhang, Yan-Ting Zhang, Shu-Min Zhao, Xiao-Yun Zhao, Shi-Jie Zheng (IHEP), Maria-Grazia Bernardini (LUPM/INAF-OAB), Laurent Bouchet (IRAP), David Corre (CEA), Patrick Maeght (LUPM), Frédéric Piron (LUPM), Jingwei Wang (IAP)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Jean-Luc Attéia (IRAP), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC), Andrea Goldwurm (APC), Diego Götz (CEA), Xu-Hui Han (NAOC), Cyril Lachaud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs.Paris), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Bing Zhang (UNLV)
report on behalf of the SVOM team:
During the commissioning phase, the SVOM/GRM was triggered in-flight by GRB 240718A at 2024-07-18T06:29:00.800 UT (T0), which was also observed by Fermi/GBM (Fermi GBM team, GCN 36898; Preis et al., GCN 36899).
The real-time alert data and light curves of SVOM/GRM were downlinked to the ground through the VHF system with low latency. The light curves show that this burst consists of multiple pulses with duration of about 15 s.
The SVOM/GRM light curves can be found at:
http://www.bursthub.cn//admin/static/svgrb240718A.png
The SVOM/GRM in-flight localization of this burst is (J2000):
RA: 234.4 deg
DEC: -10.8 deg
Error: 1.8 deg (1sigma, statistical only)
We caution that the calibration of SVOM/GRM is undergoing and this localization is subject to systematic errors. However, we note that this GRM location is broadly consistent with the Fermi/GBM. In addition, the position of this burst, as determined by GRM, is not located inside the ECLAIRs field of view.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS.
The SVOM point of contact for this burst is: Yan-Ting Zhang (IHEP) (ytzhang@ihep.ac.cn)
GCN Circular 36901
Subject
GRB 240718A: Fermi-LAT Detection
Date
2024-07-18T15:51:08Z (10 months ago)
From
Davide Depalo at Politecnico and INFN Bari <davide.depalo@ba.infn.it>
Via
Web form
D. Depalo (Politecnico & INFN Bari), E. Bissaldi (Politecnico & INFN Bari), R. Gupta (NASA/GSFC), and A. Holzmann (DF, University of Buenos Aires, Argentina) report on behalf of the Fermi-LAT Collaboration:
At 06:29:00 UT on July, 18, 2024 Fermi-LAT detected high-energy emission from GRB 240718A which was also detected by Fermi-GBM (trigger 742976945 / 240718270, GCN 36898) and SVOM/GRM (GCN 36900).
The best LAT on-ground location is found to be
RA, Dec = 252.78, -25.11 (J2000)
with an error radius of 0.23 deg (90 % containment, statistical error only).
This was 52 deg from the LAT boresight at the time of the trigger.
The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the trigger with high significance. The photon flux above 100 MeV in the time interval 0-400 s after the GBM trigger is (1.25 +/- 0.43) E-5 ph/cm2/s. The estimated photon index above 100 MeV is - 2.2 +/- 0.3.
The highest-energy photon is a 2.7 GeV event which is observed about 17 seconds after the GBM trigger.
A Swift ToO has been requested.
The Fermi-LAT point of contact for this burst is Davide Depalo (d.depalo2@phd.poliba.it).
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 36903
Subject
GRB 240718A: Fermi GBM Observation
Date
2024-07-18T17:41:09Z (10 months ago)
From
Cuán de Barra at UCD <cuan.debarra@ucdconnect.ie>
Via
Web form
C. de Barra (UCD) and C. Meegan (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 06:29:00.43 UT on 18 July 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240718A (trigger 742976945/240718270), which was also detected by Fermi-LAT (Depalo et al. 2024, GCN 36901), SPI-ACS, and SVOM/GRM (SVOM/GRM Team 2024, GCN 36900).
The Final Real-time Localization was reported previously (Fermi GBM Team 2024, GCN 36898).The Fermi GBM on-ground location is consistent with the Fermi-LAT position.
The angle from the Fermi LAT boresight is 52 degrees.
The GBM light curve consists of multiple peaks with a duration (T90)
of about 59 s (50-300 keV). The time-averaged spectrum
from T0-2.7 to T0+59.8 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 1626 +/- 106 keV.
The event fluence (10-1000 keV) in this time interval is
(5.81 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.26 s in the 10-1000 keV band is 29.9 +/- 0.5 ph/s/cm^2.
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 36905
Subject
Fermi GRB 240718A: Global MASTER-Net observations report
Date
2024-07-18T19:33:13Z (10 months 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 240718A ( Fermi GBM team, GCN 36898) errorbox 42681 sec after notice time and 42709 sec after trigger time at 2024-07-18 18:20:49 UT, with upper limit up to 15.5 mag. The observations began at zenith distance = 19 deg. The sun altitude is -30.7 deg.
The galactic latitude b = 10 deg., longitude l = 355 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2534080
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
42724 | 2024-07-18 18:20:49 | MASTER-SAAO | (16h 49m 33.00s , -25d 18m 29.3s) | C | 30 | 15.2 |
42774 | 2024-07-18 18:21:38 | MASTER-SAAO | (16h 49m 26.14s , -25d 19m 28.7s) | C | 30 | 15.5 |
42823 | 2024-07-18 18:22:28 | MASTER-SAAO | (16h 49m 33.34s , -25d 19m 11.5s) | C | 30 | 15.4 |
42877 | 2024-07-18 18:23:22 | MASTER-SAAO | (16h 49m 29.78s , -25d 17m 44.9s) | C | 30 | 15.2 |
42927 | 2024-07-18 18:24:12 | MASTER-SAAO | (16h 49m 29.74s , -25d 19m 18.0s) | C | 30 | 15.3 |
43172 | 2024-07-18 18:28:29 | MASTER-SAAO | (16h 49m 26.41s , -25d 19m 23.3s) | C | 5 | 14.7 |
43197 | 2024-07-18 18:28:54 | MASTER-SAAO | (16h 49m 33.59s , -25d 19m 06.3s) | C | 5 | 14.9 |
43225 | 2024-07-18 18:29:22 | MASTER-SAAO | (16h 49m 29.53s , -25d 17m 33.6s) | C | 5 | 15.1 |
43252 | 2024-07-18 18:29:49 | MASTER-SAAO | (16h 49m 29.54s , -25d 18m 57.2s) | C | 5 | 14.9 |
43283 | 2024-07-18 18:30:19 | MASTER-SAAO | (16h 49m 33.16s , -25d 17m 50.4s) | C | 5 | 14.8 |
43314 | 2024-07-18 18:30:51 | MASTER-SAAO | (16h 49m 26.33s , -25d 18m 21.2s) | C | 5 | 14.9 |
43343 | 2024-07-18 18:31:20 | MASTER-SAAO | (16h 49m 27.07s , -25d 17m 21.3s) | C | 5 | 14.8 |
43367 | 2024-07-18 18:31:44 | MASTER-SAAO | (16h 49m 31.97s , -25d 18m 20.6s) | C | 5 | 15.1 |
43393 | 2024-07-18 18:32:10 | MASTER-SAAO | (16h 49m 26.06s , -25d 19m 20.7s) | C | 5 | 14.6 |
43417 | 2024-07-18 18:32:34 | MASTER-SAAO | (16h 49m 32.43s , -25d 19m 07.1s) | C | 5 | 14.7 |
43442 | 2024-07-18 18:32:59 | MASTER-SAAO | (16h 49m 29.51s , -25d 17m 25.4s) | C | 5 | 14.8 |
43467 | 2024-07-18 18:33:24 | MASTER-SAAO | (16h 49m 29.48s , -25d 19m 11.9s) | C | 5 | 14.7 |
43494 | 2024-07-18 18:33:51 | MASTER-SAAO | (16h 49m 32.06s , -25d 17m 19.6s) | C | 5 | 14.9 |
43518 | 2024-07-18 18:34:15 | MASTER-SAAO | (16h 49m 26.51s , -25d 18m 18.5s) | C | 5 | 14.9 |
43549 | 2024-07-18 18:34:46 | MASTER-SAAO | (16h 49m 26.37s , -25d 17m 18.0s) | C | 5 | 14.8 |
43574 | 2024-07-18 18:35:11 | MASTER-SAAO | (16h 49m 32.19s , -25d 18m 18.2s) | C | 5 | 14.8 |
43598 | 2024-07-18 18:35:35 | MASTER-SAAO | (16h 49m 28.07s , -25d 19m 17.4s) | C | 5 | 15.1 |
43629 | 2024-07-18 18:36:06 | MASTER-SAAO | (16h 49m 33.98s , -25d 18m 54.5s) | C | 5 | 15.0 |
43653 | 2024-07-18 18:36:30 | MASTER-SAAO | (16h 49m 30.73s , -25d 17m 23.2s) | C | 5 | 14.6 |
43677 | 2024-07-18 18:36:54 | MASTER-SAAO | (16h 49m 31.09s , -25d 18m 59.1s) | C | 5 | 13.5 |
43933 | 2024-07-18 18:41:07 | MASTER-SAAO | (16h 49m 28.90s , -25d 18m 12.4s) | C | 10 | 14.0 |
43962 | 2024-07-18 18:41:37 | MASTER-SAAO | (16h 49m 30.19s , -25d 17m 12.1s) | C | 10 | 14.2 |
43991 | 2024-07-18 18:42:06 | MASTER-SAAO | (16h 49m 35.45s , -25d 18m 12.1s) | C | 10 | 14.1 |
44029 | 2024-07-18 18:42:44 | MASTER-SAAO | (16h 49m 30.96s , -25d 19m 11.0s) | C | 10 | 14.5 |
44058 | 2024-07-18 18:43:13 | MASTER-SAAO | (16h 49m 37.16s , -25d 19m 02.1s) | C | 10 | 14.6 |
44090 | 2024-07-18 18:43:45 | MASTER-SAAO | (16h 49m 34.06s , -25d 17m 38.5s) | C | 10 | 14.1 |
44122 | 2024-07-18 18:44:17 | MASTER-SAAO | (16h 49m 34.13s , -25d 18m 59.1s) | C | 10 | 14.4 |
44151 | 2024-07-18 18:44:46 | MASTER-SAAO | (16h 49m 36.55s , -25d 17m 37.3s) | C | 10 | 14.7 |
44181 | 2024-07-18 18:45:16 | MASTER-SAAO | (16h 49m 31.31s , -25d 18m 09.3s) | C | 10 | 14.9 |
44211 | 2024-07-18 18:45:46 | MASTER-SAAO | (16h 49m 31.18s , -25d 17m 08.7s) | C | 10 | 15.1 |
44240 | 2024-07-18 18:46:15 | MASTER-SAAO | (16h 49m 37.46s , -25d 18m 08.2s) | C | 10 | 14.9 |
44281 | 2024-07-18 18:46:56 | MASTER-SAAO | (16h 49m 31.70s , -25d 19m 08.0s) | C | 10 | 15.0 |
44319 | 2024-07-18 18:47:33 | MASTER-SAAO | (16h 49m 38.03s , -25d 18m 50.2s) | C | 10 | 15.0 |
44349 | 2024-07-18 18:48:04 | MASTER-SAAO | (16h 49m 35.84s , -25d 17m 18.5s) | C | 10 | 14.7 |
44380 | 2024-07-18 18:48:35 | MASTER-SAAO | (16h 49m 36.01s , -25d 18m 54.3s) | C | 10 | 14.8 |
44410 | 2024-07-18 18:49:05 | MASTER-SAAO | (16h 49m 39.77s , -25d 17m 12.7s) | C | 10 | 14.9 |
44439 | 2024-07-18 18:49:34 | MASTER-SAAO | (16h 49m 33.27s , -25d 18m 05.7s) | C | 10 | 14.9 |
44469 | 2024-07-18 18:50:04 | MASTER-SAAO | (16h 49m 32.75s , -25d 17m 05.6s) | C | 10 | 14.9 |
44498 | 2024-07-18 18:50:33 | MASTER-SAAO | (16h 49m 39.76s , -25d 18m 05.1s) | C | 10 | 15.0 |
44528 | 2024-07-18 18:51:03 | MASTER-SAAO | (16h 49m 34.55s , -25d 19m 04.1s) | C | 10 | 15.1 |
44557 | 2024-07-18 18:51:32 | MASTER-SAAO | (16h 49m 41.20s , -25d 18m 51.6s) | C | 10 | 14.9 |
44587 | 2024-07-18 18:52:02 | MASTER-SAAO | (16h 49m 37.54s , -25d 17m 22.1s) | C | 10 | 15.0 |
45632 | 2024-07-18 19:09:27 | MASTER-SAAO | (16h 49m 47.32s , -25d 18m 48.2s) | C | 10 | 13.3 |
45724 | 2024-07-18 19:10:59 | MASTER-SAAO | (16h 49m 48.12s , -25d 16m 59.8s) | C | 10 | 13.1 |
45753 | 2024-07-18 19:11:28 | MASTER-SAAO | (16h 49m 43.00s , -25d 17m 47.9s) | C | 10 | 12.3 |
45787 | 2024-07-18 19:12:02 | MASTER-SAAO | (16h 49m 44.34s , -25d 16m 47.7s) | C | 10 | 12.1 |
45817 | 2024-07-18 19:12:32 | MASTER-SAAO | (16h 49m 49.91s , -25d 17m 47.3s) | C | 10 | 13.1 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 36907
Subject
Konus-Wind detection of GRB 240718A
Date
2024-07-19T15:45:08Z (10 months ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The long-duration GRB 240718A
(Fermi-GBM detection: Fermi GBM team, GCN 36898;
Preis et al., GCN 36899; de Barra & Meegan, GCN 36903;
SVOM/GRM observation: Zhang et al., GCN 36900;
Fermi-LAT detection: Depalo et al., GCN 36901)
triggered Konus-Wind at T0=23345.357 s UT (06:29:05.357).
The burst light curve shows a multipeaked structure
which starts at ~T0-0.2 s and has a total duration of ~53 s.
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB240718_T23345/
As observed by Konus-Wind, the burst
had a fluence of 1.22(-0.11,+0.11)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+0.560 s,
of 5.04(-0.58,+0.59)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+59.648 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.91(-0.08,+0.08)
and Ep = 1355(-178,+213) keV (chi2 = 115/83 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.4
(chi2 = 115/82 dof).
The spectrum near the maximum count rate
(measured from T0+0.256 to T0+2.304 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model
with alpha = -0.38(-0.08,+0.08)
and Ep = 1126(-77,+82) keV (chi2 = 67/63 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.6
(chi2 = 67/62 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 36954
Subject
GRB 240718A: GRBAlpha detection
Date
2024-07-27T19:57:33Z (10 months 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 240718A (Fermi/GBM detection: GCN 36898; SVOM/GRM detection: GCN 36900; Konus/Wind detection: GCN 36907; INTEGRAL/SPI-ACS detection: trigger no. 10795) 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 2024-07-18 06:29:06.7 UTC. The T90 duration measured by GRBAlpha is 13.5 s and the overall significance during T90 reaches 27 sigma.
The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB240718A_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.