GRB 230827B
GCN Circular 34789
Subject
GRB 230827B: 10.4m GTC spectroscopic redshift
Date
2023-10-02T20:22:32Z (2 years ago)
From
Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>
Via
Web form
R. Sanchez-Ramirez, A. J. Castro-Tirado, Y.-D. Hu, S. Guziy, M.D. Caballero-Garcia, S.-Y. Wu, E. Fernandez-Garcia, and I. Perez-Garcia (IAA-CSIC), S. Geier (GTC, IAC), S. B. Pandey (ARIES) and B.-B. Zhang (NJU) on behalf of a larger collaboration, report:
Following the detection of AT 2023qxj by ZTF (Li et al. GCNC 34574), GIT (Swain et al. GCN 34576), and AKO (Odeh et al. GCN 34579) as the likely afterglow of Fermi GRB 230827B (Hamburg et al. GCN 34584), also detected in gamma-rays by VLUSAT-2 (Dafcikova et al. GCNC 34585), CALET (Tamura et al. GCNC 34593) and Globug/ISS (Kerr et al. GCNC 34604), we triggered the 10.4m Gran Telescopio de Canarias (GTC) equipped with Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) in La Palma (Spain), starting on Aug 29, 1 UT (~43 h after the Fermi trigger). Spectroscopy was obtained with both the R1000B (3x1200s) and R1000R (1x900s) grisms, covering the 363-1000 nm spectral range. A red continuum is noticeable, and the GTC spectrum clearly shows the Mg II doublet and Mg I absorption lines, implying a redshift of z=0.887, and thus confirming AT 2023qxj as the optical afterglow of GRB 230827B.
We thank the staff at GTC for their excellent support.
GCN Circular 34604
Subject
GRB 230827B: Glowbug gamma-ray detection
Date
2023-08-30T14:51:11Z (2 years ago)
From
matthew.kerr@gmail.com
Via
Web form
M. Kerr, C.C. Cheung, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:
The Glowbug [1,2] gamma-ray telescope, operating on the International Space Station, reports the detection of GRB 230827B, which was also detected by Fermi/GBM, VZLUSAT-2, GECAM-B (trigger 215), INTEGRAL/SPI-ACS, and CALET (GCN 34584, 34585, 34593).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-08-27 06:08:30.320 with a duration of 10.6 s and a total significance of about 57.8 sigma. The light-curve comprises two similar FRED pulses with widths of about 1s, separated by about 5s, each with tails of faint emission lasting about 5s.
Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=0.4 and a cutoff energy ("Epeak") of 272 keV. The modeled 10-10000 keV fluence is 1.3e-05 erg/cm^2.
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS. The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006
Distribution Statement A: Approved for public release. Distribution is unlimited.
GCN Circular 34601
Subject
GRB 230827B: Swift-XRT afterglow detection
Date
2023-08-30T13:26:29Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
legacy email
A. Tohuvavohu (U. Toronto), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), M. Perri (SSDC & INAF-OAR),
V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), D.N. Burrows
(PSU), J. D. Gropp (PSU) and P.A. Evans (U. Leicester) reports on
behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Fermi/GBM-detected burst GRB 230827B (GCN Circ. 34584), collecting 3.6
ks of Photon Counting (PC) mode data between T0+231.3 ks and T0+249.7
ks.
An uncatalogued X-ray source is detected consistent with being within
9.9 arcsec of the position of ZTF23abaanxz/AT2023qxj (GCN Circ. 34574)
and is believed to be the afterglow. Using 3821 s of PC mode data and 4
UVOT images, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 299.63944, +54.46318 which is equivalent to:
RA (J2000): 19h 58m 33.47s
Dec(J2000): +54d 27' 47.5"
with an uncertainty of 2.6 arcsec (radius, 90% confidence). This
position is 0.8 arcsec from the ZTF position. The light curve is
consistent with a constant source of mean count rate 7.0e-02 ct/sec. A
power-law fit gives an index of 2.490 (+0.015, -2.990).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.59 (+0.33, -0.30). The
best-fitting absorption column is 4.0 (+2.1, -1.0) x 10^21 cm^-2,
consistent with the Galactic value of 3.0 x 10^21 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum is 5.0 x 10^-11 (6.4 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 4.0 (+2.1, -1.0) x 10^21 cm^-2
Galactic foreground: 3.0 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.59 (+0.33, -0.30)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021620.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021620.
This circular is an official product of the Swift-XRT team.
GCN Circular 34596
Subject
GRB 230827B: Swift ToO observations
Date
2023-08-29T22:31:52Z (2 years 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 ToO observation of the Fermi/GBM GRB 230827B.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021620
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Fermi/GBM event. 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 34593
Subject
GRB 230827B: CALET Gamma-Ray Burst Monitor detection
Date
2023-08-29T15:56:27Z (2 years ago)
From
Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>
Via
Web form
T. Tamura (Kanagawa U), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu (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 long GRB 230827B (Fermi GBM Observation: Hamburg et al.,
GCN Circ. 34584; VZLUSAT-2 detection: Dafcikova et al., GCN
Circ. 34585) triggered the CALET Gamma-ray Burst Monitor (CGBM)
at 06:08:28.36 UTC on 27 July 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1377151581/).
The burst signal was seen by only the SGM detector.
The burst light curve shows a multi-peaked structure that starts
at T+2.3 sec, peaks at T+2.7 sec, and ends at T+87.7 sec.
The T90 and T50 durations measured by the SGM data are 79.6 +/- 3.7 sec
and 57.4 +/- 2.5 sec (40-1000 keV), respectively.
The ground-processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1377151581/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.
GCN Circular 34585
Subject
GRB 230827B: VZLUSAT-2 detection
Date
2023-08-28T17:13:25Z (2 years ago)
From
Marianna Dafčíková at Masaryk University <500025@mail.muni.cz>
Via
Web form
M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), 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 230827B (Fermi/GBM detection: GCN 34584; GECAM-B detection: trigger no. 215; CALET/CGBM detection: trigger no. 1377151581; INTEGRAL/SPI-ACS detection at 2023-08-27 ~06:08:31 UT) 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 2023-08-27 06:08:33 UTC. The T90 duration is 21 s (17 s) and the significance during T90 reaches 10.2 sigma (7.3 sigma) for detector unit no. 0 (no. 1).
The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB230827B_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.
GCN Circular 34584
Subject
GRB 230827B / GRB 230827256: Fermi GBM Observation
Date
2023-08-28T13:52:48Z (2 years ago)
From
rachel.hamburg@ijclab.in2p3.fr
Via
Web form
R. Hamburg (CNRS/IJCLab) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 06:08:30.73 UT on 27 August 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230827B (trigger 714809315/230827256).
The optical afterglow of GRB 230827B was also detected by ZTF (GCN 34574),
GIT (GCN 34576), and AKO (GCN 34579). The location of the afterglow is
consistent with the GBM on-ground calculated location, which is
RA = 299.32, Dec = +56.47 (J2000 degrees, equivalent to
J2000 19h 57m 17s, +56d 28' 12"), with a statistical
uncertainty of 2.17 degrees.
The angle from the Fermi LAT boresight is 140 degrees.
The GBM light curve shows a multi-peaked lightcurve with a duration (T90)
of about 11 s (50-300 keV). The time-averaged spectrum
from T0+0.002 to T0+10.240 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.37 +/- 0.05 and the cutoff energy,
parameterized as Epeak, is 352 +/- 52 keV.
A Band function fits the spectrum equally well
with Epeak= 256 +/- 51 keV, alpha = -1.28 +/- 0.08 and beta = -2.2 +/- 0.2.
The event fluence (10-1000 keV) in this time interval is
(1.08 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.7 s in the 10-1000 keV band is 16.4 +/- 0.9 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/"