GRB 240619C
GCN Circular 36711
Subject
GRB 240619C: AstroSat CZTI detection
Date
2024-06-20T05:56:11Z (a year ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
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 240619C. Inspection of INTEGRAL/SPI-ACS data also showed the detection of the burst.
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2024-06-19 23:44:51.50 UTC. The measured peak count rate associated with the burst is 186 (+34, -37) counts/s above the background in the combined data of three quadrants (out of four), with a total of 694 (+196, -209) counts. The local mean background count rate was 268 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 17 (+1, -5) s.
The source was also 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 2024-06-19 23:44:51.11 UTC. The measured peak count rate associated with the burst is 1471 (+90, -96) counts/s above the background in the combined data of all quadrants, with a total of 5520 (+402, -429) counts. The local mean background count rate was 1481 (+7, -8) counts/s. We measure a T90 of 14 (+1, -1) s from the cumulative Veto light curve.
Note that we see an additional peak in INTEGRAL/SPI-ACS data about 70 s after the main episode of this GRB. These peaks are very faint in our data; hence, we do not include them in our T90 calculations.
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 36716
Subject
Fermi GBM Sub-Threshold Detection of GRB 240619C
Date
2024-06-20T21:16:24Z (a year ago)
From
sumanbala2210@gmail.com
Via
Web form
S. Bala (USRA) reports on behalf of the Fermi-GBM Team:
AstroSat CZTI detected GRB 240619C at 2024-06-19 23:44:51.50 UTC (GCN 36711).
There was a Fermi-GBM onboard accidental trigger around 420s before GRB 240619C.
Due to the Fermi-GBM trigger latency, we were unable to trigger immediately on the GRB.
The GRB 240619C can be partially seen in the trigger data (trigger 740533060 / 240619984).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 340.68, Dec = -71.85 (J2000 degrees, equivalent to
J2000 22h 43m, -71d 51'), with a statistical uncertainty of 1.15 degrees.
The angle from the Fermi LAT boresight is 56 degrees.
The GBM targeted search [1], the most sensitive, coherent search for
GRB-like signals, was used to identify GRB-like emission episodes at around the AstroSAT GCN time. We find multiple emission peaks, each with a localization consistent with the on-ground localization from the Trigdat data. The brightest peak (at Fermi MET 740533496.5 s) was
found to be the most significant (S/N of 15) on the 2.048 s timescale, with a false alarm rate of 5.4e-06 Hz, using the standard search protocol. The GBM targeted search found this
brightest peak to have a "hard" GRB spectrum (Cut-off Power Law function with Epeak=1500 keV, alpha = -1.5 )
[1] Goldstein et al. 2019 arXiv:1903.12597
GCN Circular 36718
Subject
GRB 240619C: NuSTAR automated detection of the GRB
Date
2024-06-21T01:24:49Z (a year ago)
From
Brian Grefenstette at Caltech/NuSTAR <bwgref@srl.caltech.edu>
Via
Web form
B. Grefenstette (Caltech) reports on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group:
The NuSTAR SINGS working group reports the detection of prompt emission from the Long GRB 240619C in both the NuSTAR CsI anti-coincidence shields. This GRB was identified through a blind search using the CsI shield rates. Details of the search algorithm will be described in a future paper.
The NuSTAR SINGS algorithm triggered at 2024-06-19 23:44:46 (with a resolution ~5-seconds). This is consistent with the Astrosat CTZI detection (Waratkar et al, GCN circ. 36711). Using the GRB X-ray localization from Fermi (Bala, et al., GCN Circ. 36716), we estimate that the GRB was above the Earth’s horizon as seen by NuSTAR and roughly 20-deg from the telescope boresight.
The NuSTAR CsI shield data are recorded at 1 Hz. The GRB appears to be composed of multiple short, unresolved peaks superposed on broader emission. We estimate the duration at ~20-25-s, but the low overall SNR of the GRB emission makes an accurate estimate of T90 unfeasible. The shield rates are typically around 1,500 - 2,000 cps throughout the burst (typical background rates are 1,000 cps).
We confirmed that there was no significant solar activity during this period that may also produce transients in the CsI shields.
Lightcurves and analysis for this GRB can be found here:
https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2024/240619C/
Information on NuSTAR SINGS can be found here:
https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/
NuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington.
GCN Circular 36781
Subject
IPN triangulation of GRB 240619C
Date
2024-06-28T20:24:16Z (a year ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
Via
legacy email
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,
D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,
E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team,
G. Waratkar, V. Jethwani, J.Joshi, V. Bhalerao, D. Bhattacharya, and S. Vadawale, on behalf of the Astrosat-CZTI team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:
The long-duration GRB 240619С
(AstroSat-CZTI detection: Joshi et al., GCN 36711;
Fermi-GBM detection: Bala, GCN 36716;
NuSTAR anti-coincidence shields detection: Grefenstette, GCN 36718)
was detected by AstroSat (CZTI), Konus-Wind,
Fermi (during GBM trigger 740533060 record), Swift (BAT),
INTEGRAL (SPI-ACS), NuSTAR (ACS), and Mars-Odyssey (HEND)
at about 85480 s UT (23:44:40).
The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
350.990 (23h 23m 58s) -72.469 (-72d 28' 08")
Corners:
352.954 (23h 31m 49s) -73.034 (-73d 02' 03")
352.985 (23h 31m 56s) -72.971 (-72d 58' 14")
349.140 (23h 16m 34s) -71.884 (-71d 53' 02")
349.100 (23h 16m 24s) -71.947 (-71d 56' 50")
---------------------------------------------
The error box area is 307 sq. arcmin, and its maximum
dimension is 1.6 deg (the minimum one is 3.2 arcmin).
The Sun distance was 114 deg.
The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM localization.
This localization may be improved.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB240619_T85480/IPN
The HEALPix triangulation map is the multi-order HEALPix in units of probability density.
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
GCN Circular 37066
Subject
GRB 240619C: VZLUSAT-2 detection
Date
2024-08-06T12:18:13Z (a year ago)
From
Andras Pal at Konkoly Observatory <apal@szofi.net>
Via
Web form
A. Pal (Konkoly Observatory), M. Dafcikova, J. Ripa, 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 240619C (AstroSat/CZTI detection: GCN 36711; Fermi/GBM detection: GCN 36716; NuSTAR detection: GCN 36718; INTEGRAL/SPI-ACS peak detection at 2024-06-19 ~23:44:52 UTC) 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 2024-06-19 23:44:50 UTC. The T90 duration is 25 s (24 s) and the significance during T90 reaches 18 sigma (22 sigma) for detector unit no. 0 (no. 1).
The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB240619C_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.