GRB 231020A
GCN Circular 34856
Subject
GRB 231020A: Fermi GBM Final Real-time Localization
Date
2023-10-20T19:04:32Z (2 years 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 18:56:58 UT on 20 Oct 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231020A (trigger 719521023.300322 / 231020790).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 317.5, Dec = -28.7 (J2000 degrees, equivalent to J2000 21h 10m, -28d 41'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 87.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231020790/quicklook/glg_skymap_all_bn231020790.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231020790/quicklook/glg_healpix_all_bn231020790.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231020790/quicklook/glg_lc_medres34_bn231020790.gif
GCN Circular 34858
Subject
Fermi GRB 231020A: Global MASTER-Net observations report
Date
2023-10-20T19:30:48Z (2 years 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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 231020A ( Fermi GBM team, GCN 34856) errorbox 510 sec after notice time and 519 sec after trigger time at 2023-10-20 19:05:37 UT, with upper limit up to 16.7 mag. The observations began at zenith distance = 80 deg. The sun altitude is -49.5 deg.
The galactic latitude b = -42 deg., longitude l = 18 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2289661
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
569 | 2023-10-20 19:05:37 | MASTER-Kislovodsk | (21h 11m 20.75s , -28d 16m 42.1s) | P| | 100 | 16.5 |
705 | 2023-10-20 19:07:37 | MASTER-Kislovodsk | (21h 11m 26.12s , -28d 17m 47.5s) | P| | 130 | 16.7 |
870 | 2023-10-20 19:10:08 | MASTER-Kislovodsk | (21h 11m 20.36s , -28d 18m 56.3s) | P| | 160 | 16.7 |
The observation and reduction will continue.
The message may be cited.
GCN Circular 34861
Subject
GRB 231020A: BALROG localization (Fermi Trigger / GRB 231020790)
Date
2023-10-20T21:23:35Z (2 years 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
at 18:56:58 on 20 Oct. 2023 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 (1 sigma statistical errors) is:
RA(2000.0) = 316.0+/-0.4 deg
Decl.(2000.0) = -31.3+/-0.3 deg
We estimate an additional systematic error of 2 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB231020790/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB231020790/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB231020790/json
GCN Circular 34869
Subject
GRB 231020A: Fermi GBM Detection
Date
2023-10-21T15:40:20Z (2 years ago)
From
sumanbala2210@gmail.com
Via
Web form
S. Bala (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 18:56:58.30 UT on 20 October 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231020A (trigger 719521023/231020790).
The Fermi GBM Final Real-time Localization is reported in GCN 34856.
The GBM light curve consists of a single bright peak with a duration (T90)
of about 9.3 s (50-300 keV). The time-averaged spectrum
from T0-0.5 to T0+21 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.34 +/- 0.01 and the cutoff energy,
parameterized as Epeak, is 145 +/- 3 keV.
The event fluence (10-1000 keV) in this time interval is
(3.81 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+6.6 s in the 10-1000 keV band is 87.2 +/- 0.8 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 34880
Subject
GRB 231020A: AstroSat CZTI detection
Date
2023-10-25T08:23:10Z (2 years ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
Web form
P. K. Navaneeth (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 GRB 231020A which was also detected by Fermi - GBM (Fermi GBM Team, GCN Circ. 34856).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2023-10-20 18:57:05.75 UTC. The measured peak count rate associated with the burst is 144 (+46, -21) counts/s above the background in the combined data of two quadrants (out of four), with a total of 454 (+118, -182) counts. The local mean background count rate was 187 (+2, -4) counts/s. Using cumulative rates, we measure a T90 of 8 (+3, -6) s.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-10-20 18:57:05.27 UTC. The measured peak count rate associated with the burst is 1728 (+90, -99) counts/s above the background in the combined data of all quadrants, with a total of 5763 (+584, -605) counts. The local mean background count rate was 1489 (+6, -6) counts/s. We measure a T90 of 11 (+8, -2) 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 34903
Subject
GRID detection of GRB 231020A
Date
2023-10-29T11:39:09Z (2 years ago)
From
GRID Student Team at Tsinghua University <grid@tsinghua.edu.cn>
Via
Web form
Chenyu Wang and Zirui Yang report on behalf of the GRID Collaboration:
The long-duration GRB 231020A (Fermi/GBM detection: GCN Circular 34856, AstroSat CZTI detection: GCN Circular 34880) was also detected with GRID-04.
The event was triggered by GRID on 2023-10-20 at 18:56:58 UTC. The measured burst duration (T90) in the 30-2000 keV range is approximately 9.8 +/- 2.0 s seconds.
GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.
GCN Circular 34917
Subject
IPN triangulation of GRB 231020A
Date
2023-10-30T20:36:49Z (2 years 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 MGNS/BepiColombo and HEND/Mars Odyssey teams,
J. Benkhoff on behalf of the BepiColombo 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,
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 231020A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 34856;
Bala et al., GCN Circ. 34869;
BALROG localization: Preis et al., GCN Circ. 34861;
AstroSat-CZTI detection: Navaneeth et al., GCN Circ. 34880;
GRID detection: Wang and Yang, GCN Circ. 34903)
was detected by Fermi (GBM trigger 719521023), INTEGRAL (SPI-ACS),
Konus-Wind, Swift (BAT), Mars-Odyssey (HEND), BepiColombo (MGNS),
AstroSat (CZTI), and GRID, at about 68218 s UT (18:56:58).
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:
314.493 (20h 57m 58s) -29.254 (-29d 15' 15")
Corners:
314.061 (20h 56m 15s) -28.067 (-28d 04' 02")
314.696 (20h 58m 47s) -29.893 (-29d 53' 33")
314.881 (20h 59m 31s) -30.286 (-30d 17' 09")
314.275 (20h 57m 06s) -28.562 (-28d 33' 43")
---------------------------------------------
The error box area is 247 sq. arcmin, and its maximum
dimension is 2.3 deg (the minimum one is 2.2 arcmin).
The Sun distance was 101 deg.
This localization may be improved.
The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM final localization.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB231020_T68224/IPN
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
GCN Circular 35140
Subject
Konus-Wind detection of GRB 231020A
Date
2023-11-20T19:43:09Z (2 years ago)
From
Y. Temiraev at Ioffe Institute <yuri.temiraev@mail.ioffe.ru>
Via
Web form
Y. Temiraev, D. Svinkin, D. Frederiks, M. Ulanov,
A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 231020A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 34856;
Bala et al., GCN Circ. 34869;
BALROG localization: Preis et al., GCN Circ. 34861;
AstroSat-CZTI detection: Navaneeth et al., GCN Circ. 34880;
GRID detection: Wang and Yang, GCN Circ. 34903;
IPN triangulation: Kozyrev et al., GCN Circ. 34917)
triggered Konus-Wind at T0=68224.628 s UT (18:57:04.628).
The burst light curve shows a single pulse
which starts at ~T0-8.0 s and has a total duration of ~14.2 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/GRB231020_T68224/
Note: 'dip' in the count rate is due
to the GRB source occultation by the s/c structure.
As observed by Konus-Wind, the burst
had a fluence of 3.37(-0.15,+0.17)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.992 s,
of 1.09(-0.17,+0.17)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+10.240 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.00(-0.12,+0.13),
the high energy photon index beta = -3.11(-0.51,+0.26),
the peak energy Ep = 131(-7,+7) keV
(chi2 = 105/97 dof).
The spectrum near the maximum count rate
(measured from T0 to T0+2.048 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 = -0.85(-0.10,+0.11)
and Ep = 185(-9,+10) keV (chi2 = 91/69 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.3
(chi2 = 91/68 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.