- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sun 27 Aug 23 06:08:59 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 45
TRIGGER_NUM: 714809315
GRB_RA: 281.533d {+18h 46m 08s} (J2000),
281.572d {+18h 46m 17s} (current),
281.451d {+18h 45m 48s} (1950)
GRB_DEC: +64.000d {+64d 00' 00"} (J2000),
+64.026d {+64d 01' 35"} (current),
+63.945d {+63d 56' 40"} (1950)
GRB_ERROR: 5.18 [deg radius, statistical plus systematic]
GRB_INTEN: 779 [cnts/sec]
DATA_SIGNIF: 14.30 [sigma]
INTEG_TIME: 1.024 [sec]
GRB_DATE: 20183 TJD; 239 DOY; 23/08/27
GRB_TIME: 22110.73 SOD {06:08:30.73} UT
GRB_PHI: 230.00 [deg]
GRB_THETA: 150.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO: 0.55
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 90% GRB
2nd_MOST_LIKELY: 4% Cyg X-1
DETECTORS: 0,0,0, 1,1,0, 0,0,1, 0,0,0, 0,0,
SUN_POSTN: 155.64d {+10h 22m 35s} +10.13d {+10d 08' 06"}
SUN_DIST: 95.44 [deg] Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN: 281.45d {+18h 45m 47s} -27.98d {-27d 59' 00"}
MOON_DIST: 92.01 [deg]
MOON_ILLUM: 80 [%]
GAL_COORDS: 94.07, 24.76 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 337.36, 84.55 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230827256/quicklook/glg_lc_medres34_bn230827256.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 268.50,-25.60 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(2.0<100sec) coincident with the CALET_GBM event (trignum=1377151581).
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sun 27 Aug 23 06:09:09 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 58
TRIGGER_NUM: 714809315
GRB_RA: 284.450d {+18h 57m 48s} (J2000),
284.541d {+18h 58m 10s} (current),
284.257d {+18h 57m 02s} (1950)
GRB_DEC: +58.967d {+58d 58' 00"} (J2000),
+59.000d {+58d 59' 59"} (current),
+58.898d {+58d 53' 52"} (1950)
GRB_ERROR: 5.82 [deg radius, statistical plus systematic]
GRB_INTEN: 723 [cnts/sec]
DATA_SIGNIF: 22.30 [sigma]
INTEG_TIME: 2.048 [sec]
GRB_DATE: 20183 TJD; 239 DOY; 23/08/27
GRB_TIME: 22110.73 SOD {06:08:30.73} UT
GRB_PHI: 228.00 [deg]
GRB_THETA: 145.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO: 0.74
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 88% GRB
2nd_MOST_LIKELY: 8% Cyg X-1
DETECTORS: 0,0,0, 1,1,0, 0,0,1, 0,0,0, 0,0,
SUN_POSTN: 155.65d {+10h 22m 35s} +10.13d {+10d 08' 06"}
SUN_DIST: 99.64 [deg] Sun_angle= -8.6 [hr] (East of Sun)
MOON_POSTN: 281.45d {+18h 45m 48s} -27.98d {-27d 59' 00"}
MOON_DIST: 87.02 [deg]
MOON_ILLUM: 80 [%]
GAL_COORDS: 89.11, 22.21 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 317.67, 79.98 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230827256/quicklook/glg_lc_medres34_bn230827256.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 268.50,-25.60 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(2.0<100sec) coincident with the CALET_GBM event (trignum=1377151581).
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sun 27 Aug 23 06:09:17 UT
NOTICE_TYPE: Fermi-GBM Ground Position
RECORD_NUM: 57
TRIGGER_NUM: 714809315
GRB_RA: 297.170d {+19h 48m 41s} (J2000),
297.303d {+19h 49m 13s} (current),
296.888d {+19h 47m 33s} (1950)
GRB_DEC: +55.420d {+55d 25' 12"} (J2000),
+55.480d {+55d 28' 49"} (current),
+55.293d {+55d 17' 37"} (1950)
GRB_ERROR: 2.61 [deg radius, statistical only]
DATA_SIGNIF: 25.60 [sigma]
DATA_INTERVAL: 4.096 [sec]
GRB_DATE: 20183 TJD; 239 DOY; 23/08/27
GRB_TIME: 22110.73 SOD {06:08:30.73} UT
GRB_PHI: 217.00 [deg]
GRB_THETA: 141.00 [deg]
E_RANGE: 44.032 - 279.965 [keV]
LOC_ALGORITHM: 4173 (Gnd S/W Version number)
SUN_POSTN: 155.65d {+10h 22m 35s} +10.13d {+10d 08' 06"}
SUN_DIST: 107.01 [deg] Sun_angle= -9.4 [hr] (East of Sun)
MOON_POSTN: 281.45d {+18h 45m 48s} -27.98d {-27d 59' 00"}
MOON_DIST: 84.56 [deg]
MOON_ILLUM: 80 [%]
GAL_COORDS: 88.32, 14.51 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 332.35, 72.99 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230827256/quicklook/glg_lc_medres34_bn230827256.gif
POS_MAP_URL: http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_714809315.fits
COMMENTS: Fermi-GBM Ground-calculated Coordinates.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: The LC_URL file will not be created/available until ~15 min after the trigger.
COMMENTS: The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(2.0<100sec) coincident with the CALET_GBM event (trignum=1377151581).
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Sun 27 Aug 23 07:04:28 UT
NOTICE_TYPE: Fermi-GBM Final Position
RECORD_NUM: 0
TRIGGER_NUM: 714809315
GRB_RA: 299.320d {+19h 57m 17s} (J2000),
299.450d {+19h 57m 48s} (current),
299.045d {+19h 56m 11s} (1950)
GRB_DEC: +56.470d {+56d 28' 12"} (J2000),
+56.535d {+56d 32' 05"} (current),
+56.334d {+56d 20' 03"} (1950)
GRB_ERROR: 2.17 [deg radius, statistical only]
GRB_DATE: 20183 TJD; 239 DOY; 23/08/27
GRB_TIME: 22110.73 SOD {06:08:30.73} UT
GRB_PHI: 215.17 [deg]
GRB_THETA: 141.92 [deg]
E_RANGE: 50.000 - 300.000 [keV]
LOC_ALGORITHM: 415 (Gnd S/W Version number)
SUN_POSTN: 155.68d {+10h 22m 43s} +10.12d {+10d 07' 17"}
SUN_DIST: 106.94 [deg] Sun_angle= -9.6 [hr] (East of Sun)
MOON_POSTN: 282.07d {+18h 48m 18s} -27.95d {-27d 57' 00"}
MOON_DIST: 85.76 [deg]
MOON_ILLUM: 80 [%]
GAL_COORDS: 89.85, 13.93 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 337.82, 73.02 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230827256/quicklook/glg_lc_medres34_bn230827256.gif
LOC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230827256/quicklook/glg_locplot_all_bn230827256.png
COMMENTS: Fermi-GBM Final Position.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: The LC_URL file should be available by the time this FINAL notice is produced.
COMMENTS: This notice has human-in-the-loop processing.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(2.0<100sec) coincident with the CALET_GBM event (trignum=1377151581).
- GCN Circular #34574
Maggie L. Li, Jada L. Vail, Anna Y. Q. Ho (Cornell University), Michael Coughlin (University of Minnesota), Daniel Perley (LJMU), Anirudh Salgundi, Vishwajeet Swain, Gaurav Waratkar (IITB)
We report the discovery of a fast-evolving red transient by the Zwicky Transient Facility (ZTF). The transient is coincident with Fermi GRB 230827256 (trigger 714809315).
AT 2023qxj (ZTF23abaanxz) was discovered at the position (J2000) of:
RA = 19:58:33.55 (299.6397739 deg)
Dec = +54:27:48.02 (54.4633396 deg)
on 2023-08-27 07:10:10.94 UT by ZTF at r = 17.11 +/- 0.04 mag (MJD=60183.26872). ZTF obtained a non-detection 1 day prior (MJD=60182.26553) at r > 20.18 mag, indicating a fast rise rate of >3 mag/day in r. ZTF also obtained detections later that night at r = 18.88 +/- 0.08 mag (MJD=60183.33919) and g = 19.27 +/- 0.16 mag (MJD=60183.40719), implying that the transient was red and fading quickly.
The Galactic latitude of AT 2023qxj is 12.8 degrees, and the Galactic reddening toward the direction of AT 2023qxj is: E_(g-r) = 0.227 from Schlafly & Finkbeiner (2011).
The fast rise, fast decay, red color, and lack of archival optical counterpart of AT 2023qxj make it a strong candidate afterglow. We identify the coincident GRB 230827256 discovered by Fermi at the position (J2000) of:
RA = 19:57:16.8
Dec = +56:28:12
with an error radius of 2.17 deg. The time of the GRB trigger was 2023-08-27 06:08:31 UT (MJD=60183.25591), 18.45 minutes prior to the first ZTF detection of AT 2023qxj.
ZTF is supported by the National Science Foundation under Grant No. AST-2034437 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, and IN2P3, France. Operations are conducted by COO, IPAC, and UW.
- GCN Circular #34576
V. Swain, A Salgundi, R. Kumar, R. Sharma, H. Kumar, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed ZTF23abaanxz/AT2023qxj discovered by ZTF (M. L. Li et al., GCN 34574) in localization region of the Fermi GRB230827.256 (trigger No 714809315), with the 0.7m GROWTH-India Telescope (GIT). The observations started at 15:04:47 UT on 2023-08-27, roughly 8.9 hours after the Fermi GBM trigger. We obtained a 300s exposure in the r' filter. We clearly detected the candidate at the position reported by M. L. Li et al., GCN 34574. The photometric results are follow as:
------------------------------------------------------------------------------------
jd (mid) | Filter | Total Exposure (s) | Magnitude (AB) |
-------------------------------------------------------------------------------------
2460184.13030952 | r' | 300 | 19.3 +/- 0.1 |
-----------------------------------------------------------------------------------
We confirm that the object is still fading, thereby confirming it as an afterglow. The magnitude is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
- GCN Circular #34579
Mohammad Odeh, Osama Ghannam, Anas Mohammad, Khalfan Al-Noaimy, and Sameh
Al-Ashi, report on behalf of Al-Khatim Observatory (AKO) operated by the
International Astronomical Center in Abu Dhabi, UAE:
We observed ZTF23abaanxz (AT 2023qxj) discovered by ZTF (M. L. Li et al.,
GCN 34574) in the localization region of the Fermi GRB230827.256 (trigger
No 714809315), with our 0.36m f/7.7 robotic telescope. The observation was
done on 27 August 2023 starting from 18:12 (UT), about 12 hours after the
GRB trigger.
We obtained multiple 180-sec exposures in Ic and R filters. We detected the
candidate at the position reported by (M. L. Li et al., GCN 34574) and
confirmed by (Swain et al., GCN 34576).
The following observations were calculated using the Atlas catalogue as a
reference:
---------------------------------------------------------------------------=
--
ObsTime (mid), t(mid) =E2=80=93 t(0) (hours), Exposure (sec), Filter, Mag
---------------------------------------------------------------------------=
--
2023-08-27T18:31:42Z, 12.4, 13 x 180s (stacked), Ic, 18.2 +/- 0.21
2023-08-27T19:19:30Z, 13.2, 16 x 180s (stacked), R, 19.1 +/- 0.23
---------------------------------------------------------------------------=
--
The magnitudes are not corrected for galactic extinction.
- GCN Circular #34584
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/"
- GCN Circular #34585
M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werne=
r (Masaryk U.), M. Ohno (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Obs=
ervatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. =
Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rez=
enov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Researc=
h 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. Gro=
mes (VZLU), I. Vertat (FEL ZCU) -- the VZLUSAT-2/GRB payload collaboration=
.
The long duration GRB 230827B (Fermi/GBM detection: GCN 34584; GECAM-B dete=
ction: trigger no. 215; CALET/CGBM detection: trigger no. 1377151581; INTEG=
RAL/SPI-ACS detection at 2023-08-27 ~06:08:31 UT) was detected by the GRB d=
etectors 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. Th=
e 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/h=
ea/VZLUSAT-2/
The GRB detectors on VZLUSAT-2 are a demonstration payload for a future Cub=
eSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLU=
SAT-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 #34593
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 #34596
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 #34601
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 #34604
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 (G=
CN 34584, 34585, 34593).
Using an adaptive window with a resolution of 32-ms, the burst onset is det=
ermined 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 F=
RED 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/d=
E~E^x of x=3D0.4 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 func=
tion that lacks a detailed characterization of the surrounding passive stru=
cture of the ISS.
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost ga=
mma-ray transient telescopes developed, built, and operated by the U.S. Nav=
al 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=E2=80=99s 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
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Distribution Statement A: Approved for public release. Distribution is unlimited.
- GCN Circular #34789
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.
View this GCN Circular online at https://gcn.nasa.gov/circulars/34789.
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