GRB 240828A
GCN Circular 37317
Subject
GRB 240828A: Fermi GBM Final Real-time Localization
Date
2024-08-28T15:05:42Z (9 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 14:55:06 UT on 28 Aug 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240828A (trigger 746549711.829992 / 240828622).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 219.1, Dec = 35.8 (J2000 degrees, equivalent to J2000 14h 36m, 35d 47'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 93.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240828622/quicklook/glg_skymap_all_bn240828622.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/bn240828622/quicklook/glg_healpix_all_bn240828622.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240828622/quicklook/glg_lc_medres34_bn240828622.gif
GCN Circular 37321
Subject
Fermi GRB 240828A: Global MASTER-Net observations report
Date
2024-08-28T16:00:49Z (9 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-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 240828A ( Fermi GBM team, GCN 37317) errorbox 140 sec after notice time and 176 sec after trigger time at 2024-08-28 14:58:02 UT, with upper limit up to 15.9 mag. The observations began at zenith distance = 74 deg. The sun altitude is -30.0 deg.
The galactic latitude b = 66 deg., longitude l = 60 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2579196
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
196 | 2024-08-28 14:58:02 | MASTER-Amur | (14h 39m 23.80s , +35d 19m 54.3s) | P/ | 40 | 15.1 |
196 | 2024-08-28 14:58:03 | MASTER-Amur | (14h 39m 04.59s , +35d 42m 17.2s) | P\ | 40 | 15.0 |
257 | 2024-08-28 14:59:03 | MASTER-Amur | (14h 39m 23.90s , +35d 19m 55.4s) | P/ | 40 | 15.1 |
257 | 2024-08-28 14:59:03 | MASTER-Amur | (14h 39m 04.69s , +35d 42m 19.9s) | P\ | 40 | 15.3 |
329 | 2024-08-28 15:00:05 | MASTER-Amur | (14h 39m 24.07s , +35d 19m 57.8s) | P/ | 60 | 15.1 |
329 | 2024-08-28 15:00:05 | MASTER-Amur | (14h 39m 04.80s , +35d 42m 23.7s) | P\ | 60 | 15.2 |
417 | 2024-08-28 15:01:28 | MASTER-Amur | (14h 39m 24.26s , +35d 20m 00.2s) | P/ | 70 | 15.4 |
417 | 2024-08-28 15:01:28 | MASTER-Amur | (14h 39m 04.89s , +35d 42m 27.4s) | P\ | 70 | 14.5 |
519 | 2024-08-28 15:03:00 | MASTER-Amur | (14h 39m 04.99s , +35d 42m 33.0s) | P\ | 90 | 14.6 |
519 | 2024-08-28 15:03:00 | MASTER-Amur | (14h 39m 24.53s , +35d 20m 04.7s) | P/ | 90 | 14.5 |
640 | 2024-08-28 15:04:51 | MASTER-Amur | (14h 39m 24.82s , +35d 20m 08.4s) | P/ | 110 | 14.7 |
640 | 2024-08-28 15:04:51 | MASTER-Amur | (14h 39m 05.09s , +35d 42m 38.4s) | P\ | 110 | 14.9 |
787 | 2024-08-28 15:07:03 | MASTER-Amur | (14h 39m 25.20s , +35d 20m 15.8s) | P/ | 140 | 14.9 |
787 | 2024-08-28 15:07:03 | MASTER-Amur | (14h 39m 05.32s , +35d 42m 47.3s) | P\ | 140 | 15.0 |
962 | 2024-08-28 15:09:44 | MASTER-Amur | (14h 39m 25.71s , +35d 20m 24.5s) | P/ | 170 | 15.9 |
962 | 2024-08-28 15:09:44 | MASTER-Amur | (14h 39m 05.65s , +35d 42m 57.7s) | P\ | 170 | 15.7 |
1159 | 2024-08-28 15:12:56 | MASTER-Amur | (14h 39m 26.35s , +35d 20m 34.9s) | P/ | 180 | 15.5 |
1160 | 2024-08-28 15:12:56 | MASTER-Amur | (14h 39m 06.13s , +35d 43m 10.6s) | P\ | 180 | 15.6 |
1360 | 2024-08-28 15:16:16 | MASTER-Amur | (14h 39m 26.92s , +35d 20m 46.7s) | P/ | 180 | 15.5 |
1360 | 2024-08-28 15:16:16 | MASTER-Amur | (14h 39m 06.57s , +35d 43m 23.0s) | P\ | 180 | 15.6 |
The observation and reduction will continue.
The message may be cited.
GCN Circular 37327
Subject
Fermi GRB 240828A: Bassano Bresciano Observatory upper limit
Date
2024-08-28T20:57:33Z (9 months ago)
From
Ulisse Quadri at Bassano Bresciano Observatory <osservatoriobassano@gmail.com>
Via
Web form
U.Quadri, L.Strabla and P.Madurini (Bassano Bresciano Astronomical Observatory),
Members of:
GRB/UAI - Gamma ray Burst section of Unione Astrofili Italiani.
AAVSO - American Association of Variable Star Observers.
GAC - Gruppo Astrofili Cremonesi.
In a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report:
We performed optical follow-up observations of the GRB 240828A discovered by the Fermi satellite.
We used the Baker-Schmidt telescope (Diam 250mm F/3) of the (IAU station 565) Bassano Bresciano Astronomical Observatory (Italy).
The single Field of the telescope is 41.2' x 30.7'
To cover the uncertainty zone of the satellite position, we performed a mosaic of 9 images in order to cover a rectangle with sides of 2.1 x 1.5 degrees centered on the coordinates J2000 14h 36m, 35d 47'
We performed a total of 9 pointings to cover an area of 3.9 square degrees. For each pointing, 10 images were taken with duration of 20 seconds each.
The limiting magnitude is CR 17 (CR= Unfiltered with R zero point).
The sequence of pointing and the taking of images were automated by means of a telescope control software developed at our observatory.
The image analysis was performed using the subtraction method, with the template from POSS2/UKTSU Red images.
The observations started 4 hour after the GRB trigger.
For each field, we co-added 10 exposures of 20 sec each.
Start T0+ End T0+ CR lim
4.03 hour 4.81 hour 17
We did not found any credible optical counterpart in the error box of the
Fermi Satellite.
Magnitudes were estimated with the pan-STARRS cat
and are derived using Lupton (2005) equations.
Not corrected for galactic dust extinction.
Reference:
http://www.osservatoriobassano.org
The message may be cited.
GCN Circular 37328
Subject
GRB 240828A: AstroSat CZTI detection of a long burst
Date
2024-08-28T21:17:13Z (9 months ago)
From
Varun Bhalerao at IIT Bombay <varunb@iitb.ac.in>
Via
Web form
S. Srijan (IITB), G. Waratkar (IITB), J. Joshi (IUCAA), 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 240828A which was also detected by Fermi/GBM (Fermi GBM team, GCN Circ. 37317) and INTEGRAL/SPI-ACS (Trigger 10876).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-08-28 14:55:46 UTC. The measured peak count rate associated with the burst is 368 (+43, -46) counts/s above the background in the combined data of all quadrants, with a total of 4077 (+335, -387) counts. We caution that there is a 0.3 s readout dead time in CZT data during the burst which affects the calculated total counts. The local mean background count rate was 329 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 39.6 (+1.5, -1.0) s.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-08-28 14:55:45 UTC. The measured peak count rate is 1695 (+94, -66) counts/s above the background in the combined Veto data of all quadrants, with a total of 24765 (+699, -823) counts. The local mean background count rate was 1491 (+5, -6) counts/s. We measure a T90 of 39.6 (+0.5, -0.3) 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 37330
Subject
GRB 240828A: Tiled Swift observations
Date
2024-08-29T00:55:15Z (9 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a series of observations, tiled on the sky, of the
Fermi/LAT GRB 240828A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00127
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular 37331
Subject
GRB 240828A: Fermi-LAT detection
Date
2024-08-29T01:53:02Z (9 months ago)
From
Rahul Gupta at NASA GSFC <rahulbhu.c157@gmail.com>
Via
email
R. Gupta (NASA GSFC), and N. Di Lalla (Stanford University) report on
behalf of the Fermi-LAT Collaboration:
On Aug 28, 2024, Fermi-LAT detected high-energy emission from GRB 240828A,
which was also detected by Fermi-GBM (trigger 746549711 / 240828622, GCN
37317), and AstroSat CZTI (GCN 37328).
The best LAT on-ground location is found to be:
RA, Dec = 225.49, 36.64 (J2000)
with an error radius of 0.30 deg (90 % containment, statistical error only).
This was 93 deg from the LAT boresight at the time of the GBM trigger: T0 =
14:55:06 UT.
The data from the Fermi-LAT show a significant increase in the event rate
that is spatially and temporally correlated with the GBM emission with high
significance. The photon flux above 100 MeV in the time interval 3500-6100
s after the GBM trigger is (8.2 +/- 3.8) E-7 ph/cm2/s. The estimated photon
index above 100 MeV is -2.1 +/- 0.4.
The highest-energy photon is a 1.7 GeV event which is observed ~ 5400
seconds after the GBM trigger.
A Swift ToO has been approved for this burst.
The Fermi-LAT point of contact for this burst is Niccolo' Di Lalla (
niccolo.dilalla@stanford.edu).
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 37337
Subject
GRB 240828A: Swift-XRT afterglow detection
Date
2024-08-29T12:58:35Z (9 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
A.P. Beardmore (U. Leicester), B. Sbarufatti (INAF-OAB), C. Salvaggio
(INAF-OAB), M. Ferro (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU),
M. A. Williams (PSU), J.P. Osborne (U. Leicester) and P.A. Evans (U.
Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 240828A in a series of observations tiled
on the sky. The total exposure time is 3.3 ks, distributed over 3
tiles; the maximum exposure at a single sky location was 2.3 ks. The
data were collected between T0+42.1 ks and T0+60.2 ks, and are entirely
in Photon Counting (PC) mode.
Six uncatalogued X-ray sources are detected, of which one ("Source 3")
is above the RASS 3-sigma upper limit at this position, and is
therefore likely the GRB afterglow. The position of this source is RA,
Dec=225.5130, +36.5285 which is equivalent to:
RA (J2000): 15:02:3.12
Dec(J2000): +36:31:42.5
with an uncertainty of 3.9 arcsec (radius, 90% confidence). This
position is 6.8 arcmin from the Fermi/LAT position.
The light curve can be modelled with a power-law decay with a decay
index of alpha=3.043 (+0.027, -0.580).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.47 (+0.33, -0.24). The
best-fitting absorption column is consistent with the Galactic value
of 1.3 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum is 3.7 x 10^-11 (3.8 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.3 (+/-6.6) x 10^20 cm^-2
Galactic foreground: 1.3 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.47 (+0.33, -0.24)
If the light curve continues to decay with a power-law decay index of
3.043, the count rate at T+24 hours will be 0.014 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.3 x
10^-13 (5.3 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021707.
The results of the full analysis of the tiled XRT observations are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00127.
This circular is an official product of the Swift-XRT team.
GCN Circular 37339
Subject
GRB 240828A: KAIT Optical Afterglow Candidate
Date
2024-08-29T16:28:18Z (9 months ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
legacy email
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, observed the field of GRB 240828A (The Fermi
GBM team, GCN 37317; Srijan et al., GCN 37328) around the
Fermi/LAT position (Gupta & Lalla, GCN 37331) starting at 03:32,
Aug. 29 UT, about 12.61 hours after the burst. Observations were
performed in 3 x 3 tiling mode, a set of clear (roughly R) filter
images were obtained. Within the XRT afterglow (Beardmore et al.,
GCN 37337) error circle, we detected a bright uncataloged optical
afterglow candidate at J2000 position of (error ~0.5"):
RA: 15:02:02.97
Dec: +36:31:43.93
We estimate the clear band magnitude to be ~17.9 mag at 12.69 hours
after the burst. Further observations are encouraged.
GCN Circular 37341
Subject
GRB 240828A: Fermi GBM Observation
Date
2024-08-29T19:24:23Z (9 months ago)
From
Sarah Dalessi at UAH <sd0104@uah.edu>
Via
Web form
S. Dalessi (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 14:55:06.83 UT on 28 August 2024, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 240828A (trigger 746549711/240828622).
which was also detected by AstroSat (S. Srijan et al. 2024, GCN 37328), Fermi-LAT (R. Gupta et al. 2024, GCN 37331), Swift-XRT (A.P. Beardmore et al. 2024, GCN 37337), and KAIT (W. Zheng et al. 2024 37339)
The Fermi GBM on-ground location is consistent with the AstroSat, Fermi-LAT, Swift-XRT, and KAIT positions.
The angle from the Fermi LAT boresight is 97 degrees.
The GBM light curve multiple peaks with a duration (T90)
of about 41.2 s (50-300 keV). The time-averaged spectrum
from T0+0.002 to T0+44.225 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.96 +/- 0.01 and the cutoff energy,
parameterized as Epeak, is 850 +/- 30 keV.
The event fluence (10-1000 keV) in this time interval is
(8.05 +/- 0.07)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+38.8 s in the 10-1000 keV band is 18.6 +/- 0.4 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 820 +/- 30 keV, alpha = -0.96 +/- 0.01 and beta = -2.9 +/- 0.2.
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 37344
Subject
GRB 240828A: SAO RAS optical observations
Date
2024-08-29T21:25:40Z (9 months ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin and O. I. Spiridonova (SAO RAS)
report on behalf of the GRB follow-up team.
We observed the field of GRB 240828A (Fermi GBM team, GCN 37317;
Srijan et al., GCN 37328; Gupta and Di Lalla, GCN 37331;
Beardmore et al., GCN 37337; Dalessi and Meegan GCN 37341)
with the SAO RAS 1-meter telescope Zeiss-1000 equipped with
the CCD-photometer. We obtained 3 x 300 sec frames in each of BVRcIc
filters on August 29.
The OT (Zheng and Filippenko; GCN 37339) is clearly detected in our
images. The results are as follows.
Start -- Stop, UT t_mid - T0, d filter mag +/- err
18:14:38 -- 18:33:37 1.14515 B 20.54 +/- 0.05
18:34:12 -- 18:50:59 1.15798 V 20.16 +/- 0.05
17:38:50 -- 17:56:05 1.11969 Rc 19.73 +/- 0.03
17:56:52 -- 18:13:53 1.13213 Ic 19.36 +/- 0.07
Magnitudes were calibrated against nearby SDSS stars (converted with
Lupton 2005 equations) and not corrected for the MW extinction.
GCN Circular 37349
Subject
GRB 240828A: KAIT continued optical observations
Date
2024-08-30T07:06:20Z (9 months ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
legacy email
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, continued observing the optical afterglow of
GRB 240828A (Zheng et al., GCN 37339; Moskvitin et al., GCN
37344) starting at ~1.54 days after the burst. A set of 31x60s
clear (roughly R) filter images were obtained. The afterglow
was clearly detected in our coadd image and we measure its
brightness has faded to be 20.2 +/- 0.2 mag.
GCN Circular 37370
Subject
GRB 240828A: SAO RAS AS-500(2) optical observations
Date
2024-09-01T21:05:37Z (9 months ago)
From
Moskvitin Alexander at SAO RAS <mosk@sao.ru>
Via
legacy email
A. S. Moskvitin and V. V. Vlasyuk (SAO RAS),
report on behalf of the GRB follow-up team.
We observed the field of GRB 240828A (Fermi GBM team, GCN 37317;
Srijan et al., GCN 37328; Gupta and Di Lalla, GCN 37331;
Beardmore et al., GCN 37337; Dalessi and Meegan GCN 37341)
with the AS-500(2) 0.5-m Ritchey-Chretien telescope of SAO RAS
equipped with CCD-photometer and Andor iXon Ultra EM-CCD DU-897
camera with 512x512 pixels E2V chip. We obtained 40 x 90 sec. images
in Rc band on August 31 (2024-08-31T18:44:29 -- 2024-08-31T19:59:08),
t_mid - T0 = 3.1852 days.
The OT (Zheng and Filippenko, GCNs 37339, 37349; Moskvitin
and Spiridonova, GCN 37344) is marginally detected in our stacked
frame with the brightness of R = 21.8 +/- 0.3 calibrated against
nearby SDSS stars (magnitudes converted with Lupton 2005 equations)
and not corrected for the MW extinction.
GCN Circular 37377
Subject
GRB 240828A: GECAM detection
Date
2024-09-03T07:43:57Z (9 months ago)
From
yqzhang_cl@163.com
Via
Web form
Yan-Qiu Zhang (IHEP), Shao-Lin Xiong (IHEP), Chen-Wei Wang (IHEP) report on behalf of the GECAM team:
GECAM-C was triggered on-ground by a long burst, GRB 240828A, at 2024-08-28T14:55:07.150 UTC (T0), which was also detected by Fermi/GBM (Fermi GBM team, GCN #37317; S. Dalessi et al., GCN #37341), AstroSat CZTI (S. Srijan et al., GCN #37328), Fermi-LAT (R. Gupta et al., GCN #37331), Swift-XRT (A.P. Beardmore et al., GCN #37337) and INTEGRAL/SPI-ACS (trigger #10876).
According to the GECAM-C light curves in about 6-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of about 41.41（+1.13,-1.05）s.
The time-averaged spectrum from T0+0.83 to T0+42.24 s could be fit by a power law with high energy exponential cutoff function with a fluence of about 7.77E-05 erg/cm^2 in 10-1000 keV.
The GECAM light curve could be found here:
https://twikinew.ihep.ac.cn/pubgecam/Sandbox/GRB/GECAMC_lC_GRB240828A.png
The GECAM-C on-ground location (J2000) is:
Ra: 227.7 deg
Dec: 39.9 deg
Err: 1.8 deg (1-sigma, statistical only)
GECAM location is consistent with the Fermi/LAT position within the error.
We note that these results are very preliminary. Refined analysis will be reported later.
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
GCN Circular 37382
Subject
GRB 240828A: SVOM/GRM observation
Date
2024-09-04T08:42:47Z (9 months ago)
From
yqzhang_cl@163.com
Via
Web form
SVOM/GRM team: Yan-Qiu Zhang, Shi-Jie Zheng, Chen-Wei Wang, Wen-Jun tan, Yong-Wei Dong, Jiang-Tao Liu, Jian-Chao Sun, Yue Huang, Jiang He, Min Gao, Hao-Xuan Guo, Lu Li, Yong-Ye Li, Hong-Wei Liu, Xin Liu, Hao-Li Shi, Li-Ming Song, 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, Wen-Long Zhang, Yan-Ting Zhang, Shu-Min Zhao, Xiao-Yun Zhao, Chao Zheng (IHEP), Maria-Grazia Bernardini (LUPM/INAF-OAB), Laurent Bouchet (IRAP), David Corre (CEA), Tais Maiolino (LUPM), Frédéric Piron (LUPM), Stéphane Schanne (CEA), Jingwei Wang (IAP)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), JeanLuc 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 detected a long GRB 240828A at 2024-08-28T14:55:07.200 UT (T0), which was also observed by Fermi/GBM (Fermi GBM team, GCN #37317; S. Dalessi et al., GCN #37341), AstroSat CZTI (S. Srijan et al., GCN #37328), Fermi-LAT (R. Gupta et al., GCN #37331), GECAM (Yan-Qiu Zhang et al., GCN #37377) and INTEGRAL/SPI-ACS (trigger #10876).
At the time of this burst ECLAIRs was not acquiring data.
With the event-by-event data downloaded through the X-band ground station, the light curve shows that this burst consists of multiple pulses with a duration of about 45 s.
The SVOM/GRM light curve can be found here:
http://www.bursthub.cn//admin/static/svgrb240828A.png
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/GRM point of contact for this burst is: Yan-Qiu Zhang (IHEP)(zhangyanqiu@ihep.ac.cn)