GRB 210727A
GCN Circular 30531
Subject
GRB 210727A: BALROG localization (Fermi Trigger 649072251 / GRB 210727410)
Date
2021-07-27T11:44:42Z (4 years ago)
From
Jochen Greiner at MPE,Garching <jcg@mpe.mpg.de>
B. Biltzinger, F. Kunzweiler, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
649072251 at 09:50:46 on 27 July 2021 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) = 184.2+/-6.6 deg
Decl.(2000.0) = -64.3+/-3.5 deg
We estimate an additional systematic error of 2 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210727410/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210727410/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210727410/json
GCN Circular 30533
Subject
GRB 210727A: AGILE/MCAL detection
Date
2021-07-27T14:43:39Z (4 years ago)
From
Alessandro Ursi at INAF/IAPS <alessandro.ursi@gmail.com>
A. Ursi (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), M. Pilia
(INAF/OA-Cagliari), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A.
Argan, M. Cardillo, C. Casentini, Y. Evangelista, G. Piano, A. Ursi
(INAF/IAPS), F. Lucarelli, C. Pittori (SSDC, and INAF/OAR), A. Bulgarelli,
V. Fioretti, F. Fuschino, N. Parmiggiani (INAF/OAS-Bologna), M. Marisaldi
(INAF/OAS-Bologna, and Bergen University), A. Trois (INAF/OA-Cagliari), I.
Donnarumma (ASI), F. Longo (Univ. Trieste and INFN Trieste), A. Giuliani
(INAF/IASF-Mi), report on behalf of the AGILE Team:
The AGILE Mini-CALorimeter (MCAL) detected the short GRB 210727A (Fermi
trigger no. 649072251) at T0 = 2021-07-27 09:50:47.40 +/- 0.01 s (UTC).
The event lasted about 1.5 s and released a total number of ~1300 counts in
the detector (in the 0.4-100 MeV energy range), above an average background
rate of 560 Hz. The MCAL light curve can be found at
http://www.agilescienceapp.it/notices/074097_GRB_MCAL_554464247.402495.png .
The time-integrated spectrum of the burst can be fitted in the energy range
0.4-20 MeV with a single power-law with ph.ind. = -1.59 -/+ 0.07, resulting
in a reduced chi-squared of 1.23 (62 d.o.f.) and a fluence of 9.6e-06
ergs/cm^2 (90% confidence level), in the same energy range.
The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the
energy range 0.4-100 MeV. Additional analysis of AGILE data is in progress.
Automatic MCAL GRB alert Notices can be found at:
https://gcn.gsfc.nasa.gov/agile_mcal.html.
GCN Circular 30541
Subject
IPN triangulation of GRB 210727A (short)
Date
2021-07-28T18:09:24Z (4 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
A. Ridnaia, S. Golenetskii, D. Frederiks, D. Svinkin,
A. Lysenko, and T. Cline on behalf of the Konus-Wind team,
K. Hurley, on behalf of the IPN,
A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
on behalf of the Fermi GBM team,
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, report:
The short-duration GRB 210727A
(BALROG localization: Biltzinger et al., GCN 30531;
AGILE-MCAL detection: Ursi et al., GCN 30533)
was detected by Fermi (GBM trigger 649072251), Konus-Wind,
INTEGRAL (SPI-ACS), Swift (BAT), AGILE (MCAL),
and CALET (CGBM) at about 35447 s UT (09:50:47).
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:
189.231 (12h 36m 55s) -59.926 (-59d 55' 35")
Corners:
194.539 (12h 58m 09s) -56.353 (-56d 21' 12")
193.795 (12h 55m 11s) -56.308 (-56d 18' 30")
182.624 (12h 10m 30s) -63.300 (-63d 17' 59")
183.549 (12h 14m 12s) -63.394 (-63d 23' 37")
---------------------------------------------
The error box area is 3.28 sq. deg, and its maximum
dimension is 9.14 deg (the minimum one is 22 arcmin).
The Sun distance was 93 deg.
This box may be improved.
The IPN localization is consistent with, but reduces the area of, the
Fermi final position and the BALROG localization.
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB210727_T35447/IPN
The Konus-Wind time history and spectrum will be given in a forthcoming GCN
Circular.
GCN Circular 30544
Subject
GRB 210727A: CALET Gamma-Ray Burst Monitor detection
Date
2021-07-29T10:11:54Z (4 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
Y. Akaike (Waseda U),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka (ICRR), S. Torii, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The short GRB 210727A (BALROG localization: Biltzinger et al.,
GCN Circ. 30531; AGILE/MCAL detection: Ursi et al., GCN Circ. 30533;
IPN triangulation: Ridnaia et al., GCN Circ. 30541;
https://gcn.gsfc.nasa.gov/other/210727A.gcn3) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 09:50:46.605 UTC on 27 July 2021.
The burst signal was seen by all CGBM detectors.
The burst light curve shows a multi-peaked structure which starts at
T-0.38 sec and ends at T+0.64 sec. The T90 and T50 durations measured by
the SGM data are 0.96 +- 0.14 sec and 0.51 +- 0.09 sec (40-1000 keV),
respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1311414395/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.
GCN Circular 30549
Subject
GRB 210727A: AstroSat CZTI detection
Date
2021-07-30T06:21:59Z (4 years ago)
From
Gaurav Waratkar at IIT,Bombay <gauravwaratkar@iitb.ac.in>
V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (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,
2020, arxiv:2011.07067) showed detection of a short GRB 210727A, which
was also detected by Fermi-GBM (Trigger no. 649072251), AGILE/MCAL (Ursi
et al., GCN 30533), CALET (Akaike et al., GCN 30544), with IPN
localization (Ridnaia et al., GCN 30541) and BALROG localization
(Biltzinger et al., GCN 30531).
The source was clearly detected in the 20-200 keV energy range. The
light curve showed multiple peaks of emission with the strongest peak at
2021-07-27 09:50:46.45 UT. The measured peak count rate associated with
the burst is 890 (+197, -153) cts/s above the background in the combined
data of four quadrants, with a total of 489 (+74, -67) cts. The local
mean background count rate was 482 (+11, -15) cts/s. Using cumulative
rates, we measure a T90 of 0.9 (+0.3, -0.1) s.
It was also detected in the CsI anticoincidence (Veto) detector in the
100-500 keV energy range.
CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC
and PRL. The Indian Space Research Organisation funded, managed and
facilitated the project.