GRB 230512A
GCN Circular 33808
Subject
Improved IPN triangulation of GRB 230512A
Date
2023-05-17T12:02:03Z (2 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the MGNS/BepiColombo team,
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,
and
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, report:
Using the BepiColombo (MGNS) data we have improved
the previous IPN box (Svinkin et al., GCN Circ. 33802),
The coordinates of the updated 3 sigma error box are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
295.623 (19h 42m 30s) +38.267 (+38d 16' 00")
Corners:
295.645 (19h 42m 35s) +38.328 (+38d 19' 39")
295.609 (19h 42m 26s) +38.353 (+38d 21' 10")
295.601 (19h 42m 24s) +38.206 (+38d 12' 20")
295.637 (19h 42m 33s) +38.180 (+38d 10' 49")
---------------------------------------------
The error box area is 15 sq. arcmin, and its maximum
dimension is 10 arcmin (the minimum one is 1.7 arcmin).
The Sun distance was 96 deg.
This box may be further improved.
None of the optical and X-ray transients found during the burst follow-up (GCNs 33784, 33789, 33796) are inside the box.
An updated triangulation map and HEALPix FITS files are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230512_T23265/IPN/
GCN Circular 33802
Subject
IPN triangulation of GRB 230512A
Date
2023-05-15T10:17:05Z (2 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
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,
and
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, report:
The bright GRB 230512A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 33778;
Roberts et al., GCN Circ. 33785;
AstroSat-CZTI detection: Navaneeth et al., GCN Circ. 33779;
Fermi-LAT detection: Maheso et al., GCN Circ. 33780;
GRBAlpha detection: Dafcikova et al., GCN Circ. 33795)
was detected by Fermi (GBM trigger 705565670; LAT), AstroSat (CZTI),
Konus-Wind, GRBAlpha, and Swift (BAT) at about 23265 s UT (06:27:45).
The burst was outside the coded field of view of the BAT.
We have triangulated it to a Konus-GBM annulus centered at
RA(2000)=252.326 deg (16h 49m 18s) Dec(2000)=-21.096 deg (-21d 05' 46"),
whose radius is 71.928 +/- 0.057 deg (3 sigma).
The LAT position reported by Maheso et al. (GCN Circ. 33780)
is consistent with the annulus. The annulus combined with
the LAT (90 % containment, statistical-only) error circle
gives the following error box:
---------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------
Center:
295.4160 +38.4139
Corners:
295.6484 +38.1720
295.7385 +38.2604
295.1883 +38.6501
295.0849 +38.5708
---------------------------------
The error box area is 242.2 sq. arcmin (a factor of ~4
smaller than that of the LAT error circle), and its maximum
dimension is 0.6 deg (the minimum one is 6.8 arcmin).
The Sun distance was 96 deg.
This box may be improved.
The Swift-XRT sources #2, 4, 8 (https://www.swift.ac.uk/xrt_products/TILED_GRB00111/) are inside the error box.
The OT candidate (Belkin et al., GCN Circ. 33796) is outside the error box.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230512_T23265/IPN/
The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.
GCN Circular 33800
Subject
GRB 230512A: Nanshan/NEXT non-detection of GRB afterglow candidate
Date
2023-05-14T23:03:22Z (2 years ago)
From
Dong Xu at NAOC/CAS <dxu@nao.cas.cn>
S.Q. Jiang, T.H. Lu, S.Y. Fu, X. Liu, Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of Fermi LAT localization (Maheso et al., GCN 33780) of short bright GRB 230512A (Fermi GBM team, GCN 33778; AstroSat, GCN 33779 and GRBAlpha, GCN 33795)
using the NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China.
No optical source is detected in our stacked images at the XRT source 5 position. Preliminary photometric results are as follows:
T_mid-T0(day) Filter Upper_Limit(3-sigma)
0.537 r 20.7
1.543 r 21.8
1.563 z 20.0
calibrated with the nearby PS1 stars and not corrected for Galactic extinction. The NEXT's first epoch image doesn't reveal the Kitab candidate (Belkin et al., GCN 33796), although it is deeper.
Some other XRT sources are also covered, and so far no credible optical afterglow candidate can be claimed.
GCN Circular 33799
Subject
GRB 230512A: Zwicky Transient Facility non-detection of GRB afterglow candidate
Date
2023-05-14T17:10:39Z (2 years ago)
From
Tomas Ahumada at U. of Maryland <tahumada@astro.umd.edu>
Tomas Ahumada (CIT), Michael Coughlin (UMN), Igor Andreoni (UMD), Varun
Bhalerao (IITB) on behalf of the ZTF collaboration:
We analyze the ZTF images containing the afterglow candidate (Belkin et
al., GCN Circ. 33796) and no sources were found up to the following limits:
UTC observation , t-t0 , filter, upper limit
2023-05-13 06:33:14, 1.003 , r , 21.02 mag
2023-05-13 06:25:09, 0.998 , g , 20.83 mag
ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC,
USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY,
Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan;
IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No
1440341.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski
(Duev et al. 2019). GROWTH India telescope is located at the Indian
Astronomical Observatory (Hanle), operated by the Indian Institute of
Astrophysics (IIA). GROWTH-India project is supported by SERB and
administered by IUSSTF, under grant number IUSSTF/PIRE
Program/GROWTH/2015-16 and IUCAA.
--
Tomás Ahumada (he/him)
Ph.D. Candidate
Department of Astronomy
University of Maryland, College Park
NASA <tomas.f.ahumdamena@nasa.gov> Goddard Space Flight Center, Code 661
B.Sc. Astronomy, Pontificia Universidad Católica de Chile
GCN Circular 33798
Subject
GRB 230512A: Liverpool Telescope observations
Date
2023-05-14T17:03:28Z (2 years ago)
From
Ben Gompertz at U of Birmingham <b.gompertz@bham.ac.uk>
B. P. Gompertz (U. Birmingham), D. B. Malesani (U. Radboud and DAWN/NBI) and A. J. Levan (U. Radboud) report:
We tiled part of the LAT localisation (Maheso et al., GCN 33780) of GRB 230512A (Fermi GBM Team, GCN 33778; Navaneeth et al., GCN 33779; Dafcikova et al., GCN 33795) with the IO:O optical camera on the 2m robotic Liverpool Telescope. XRT source 5 (Osborne et al., GCN 33789) was covered by an observation beginning on May 13, 2023 at 03:10:22 UT and consisting of a series of 6x150 s exposures in the SDSS r' filter.
We detect no source at the position of the candidate optical counterpart reported by Kitab (Belkin et al., GCN 33796) to a 3-sigma limit of r’ > 22.15, ~7.5 hours after the reported detection. We also detect the PS1 source at a magnitude consistent with the catalogued value.
No other candidate optical counterparts have been identified in our imaging, which also covers XRT sources 8 and 10, to typical limits of r' > 22. Analysis is ongoing.
Magnitudes are in the AB system, calibrated against nearby PS1 stars (Chambers et al., 2016), and are not corrected for extinction along the line of sight.
GCN Circular 33797
Subject
GRB 230512A: GIT non detection of afterglow candidate
Date
2023-05-14T16:41:15Z (2 years ago)
From
Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>
V. Swain (IITB), H. Kumar (IITB), A. Salgundi (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed the region of short GRB 230512A (Fermi GBM team, GCN 33778 and D. J. Maheso et al., GCN 33780), with the 0.7m GROWTH-India Telescope (GIT) covering the position of afterglow detected by S. Belkin et al., GCN 33796, . The observations started at 20:41:30 UT on 2023-05-12, 14.22 hours after the Fermi GBM trigger and 1.4 hours after the commencement of Kitab RC-36 observations (Belkin et al., GCN #33796). We obtained two exposures of 400s each in the r' band, coincidentally overlapping with the end of their first epoch. We later imaged the field in the g' band as well, with 2x400s exposures. We search individual images and the stacked image for an afterglow, but find no afterglow candidates. In particular, we do not detect the optical afterglow emission reported by S. Belkin et al., GCN 33796, despite our images having sufficient depth. Our upper limits are as follows:
-----------------------------------------------------------------------------
JD (mid) | T_mid-T0(hrs) |T_mid - T(Kitab)|Filter | Total Exposure (s) | Lim_mag (5-sigma) |
-----------------------------------------------------------------------------
2460077.364615665 | 14.28 | 1.46 | r' | 2 X 400 (stacked) | >20.39 |
2460077.43835897 | 15.88 | 3.05 | g' | 2 x 400 (stacked) | >21.08 |
----------------------------------------------------------------------------
We note that there is no known minor planet at this location in MPC. The magnitudes are 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 operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
GCN Circular 33796
Subject
GRB 230512A: Kitab possible afterglow candidate
Date
2023-05-14T12:41:26Z (2 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
S. Belkin (IKI), A. Schmalz (KIAM), A. Pozanenko (IKI), N. Pankov (HSE), Sh. Ehgamberdiev (UBAI) report on behalf of IKI-GRB-FuN:
We observed the field of Fermi LAT localization (Maheso et al., GCN 33780) of short bright GRB 230512A (Fermi GBM team, GCN 33778; detected also by AstroSat GCN 33779, and GRBAlpha GCN 33795) with Kitab RC-36 telescope. Observation in Clear filter started on May, 12 (UT) 19:17:32 and continued on May, 13 (UT) 20:49:59. We cover XRT sources ## 2,4,5,7,8,9,10,11 (Osborne et al., GCN 33789).
Within the XRT #5 error circle, we detected a possible optical source on May 12 and did not detect the source on May 13. The source is also absent in PS1 catalog. The coordinate of the source are
(J2000) 19:40:49.49 +38:28:07.4
with uncertainness of 0.5 arcsec in both coordinates. The nearest PS object is 2.5 arcses East with r'=22.14.
Preliminary photometry of the source in combined images is following
Date, UT start, t-T0, Exp., Filter, OT, Err, UL(3 sigma)
(mid, days)
2023-05-12 19:17:32 0.57624 120*60 Clear 19.43 0.25 19.7
2023-05-13 20:49:59 1.64044 120*60 Clear n/d n/d 20.0
The photometry is based on nearby USNO-B1.0 stars, R2 magnitude and not corrected for Galaxy extinction.
USNO-B1.0 stars
RA Dec R2
19:40:50.8094400 +38:29:37.881600 14.55
19:40:53.3748000 +38:29:06.702000 15.30
19:40:46.4635200 +38:06:31.770000 14.15
19:41:16.4054400 +38:09:39.092400 15.80
Taking photometry in the first epoch and an upper limit on the second epoch the index of power law decay is less than -0.5.
GCN Circular 33795
Subject
GRB 230512A: GRBAlpha detection
Date
2023-05-14T08:29:43Z (2 years ago)
From
Marianna Dafčíková at Masaryk University <500025@mail.muni.cz>
M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), yyT. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.
The GRB 230512A (Fermi/GBM detection: GCN 33778; Fermi/LAT detection: GCN 33780; AstroSat detection: GCN 33779) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).
The detection was confirmed at the peak time 2023-05-12 06:27:47 UTC. The T90 duration measured by GRBAlpha is 4 s and the overall significance during T90 reaches 11 sigma.
The light curve obtained by GRBAlpha is available here:
https://grbalpha.konkoly.hu/static/share/GRB230512A_GCN.pdf
All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume.
GCN Circular 33789
Subject
GRB 230512A: Swift-XRT observations
Date
2023-05-13T08:06:19Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
J.P. Osborne (U. Leicester), A. Melandri (INAF-OAR), T. Sbarrato
(INAF-OAB), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), A. Tohuvavohu
(U. Toronto), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P.
Beardmore (U. Leicester) and P.A. Evans (U. Leicester) report on behalf
of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 230512A in a series of observations tiled
on the sky. The total exposure time is 4.9 ks, distributed over 4
tiles; the maximum exposure at a single sky location was 2.3 ks. The
data were collected between T0+45.5 ks and T0+57.3 ks, and are entirely
in Photon Counting (PC) mode.
Nine uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:
Source 1:
RA (J2000.0): 295.4803 = 19:41:55.26
Dec (J2000.0): +38.6649 = +38:39:53.6
Error: 4.2 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: (8.8 [+3.9, -3.0])e-3 ct s^-1
Distance: 980 arcsec from Fermi/LAT position.
Flux: (5.1 [+2.2, -1.8])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 3:
RA (J2000.0): 295.5430 = 19:42:10.33
Dec (J2000.0): +38.7526 = +38:45:09.4
Error: 5.5 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: 0.0176 [+0.0056, -0.0047] ct s^-1
Distance: 1331 arcsec from Fermi/LAT position.
Flux: (3.57 [+1.13, -0.95])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 5:
RA (J2000.0): 295.2060 = 19:40:49.43
Dec (J2000.0): +38.4686 = +38:28:07.1
Error: 6.2 arcsec (radius, 90% conf.)
Count-rate: 0.0105 [+0.0042, -0.0034] ct s^-1
Distance: 600 arcsec from Fermi/LAT position.
Source 6:
RA (J2000.0): 295.7616 = 19:43:2.79
Dec (J2000.0): +38.3644 = +38:21:51.9
Error: 3.9 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: (6.7 [+3.5, -2.6])e-3 ct s^-1
Distance: 1028 arcsec from Fermi/LAT position.
Source 7:
RA (J2000.0): 295.0895 = 19:40:21.48
Dec (J2000.0): +38.4348 = +38:26:05.5
Error: 6.8 arcsec (radius, 90% conf.)
Count-rate: (5.4 [+3.3, -2.4])e-3 ct s^-1
Distance: 884 arcsec from Fermi/LAT position.
Source 8:
RA (J2000.0): 295.3130 = 19:41:15.11
Dec (J2000.0): +38.4565 = +38:27:23.3
Error: 5.1 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: (8.7 [+4.1, -3.2])e-3 ct s^-1
Distance: 318 arcsec from Fermi/LAT position.
Source 9:
RA (J2000.0): 295.2484 = 19:40:59.62
Dec (J2000.0): +38.1016 = +38:06:05.7
Error: 7.7 arcsec (radius, 90% conf.)
Count-rate: (5.5 [+3.1, -2.3])e-3 ct s^-1
Distance: 1156 arcsec from Fermi/LAT position.
Source 10:
RA (J2000.0): 295.1589 = 19:40:38.13
Dec (J2000.0): +38.4685 = +38:28:06.6
Error: 6.1 arcsec (radius, 90% conf.)
Count-rate: (9.8 [+5.8, -4.3])e-3 ct s^-1
Distance: 723 arcsec from Fermi/LAT position.
Source 11:
RA (J2000.0): 295.2125 = 19:40:50.99
Dec (J2000.0): +38.0868 = +38:05:12.5
Error: 4.5 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: (9.5 [+4.1, -3.2])e-3 ct s^-1
Distance: 1245 arcsec from Fermi/LAT position.
Flux: (3.3 [+1.4, -1.1])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Two catalogued sources were also detected.
The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00111.
This circular is an official product of the Swift-XRT team.
GCN Circular 33786
Subject
GRB 230512A: GIT optical follow-up ZTF candidates
Date
2023-05-12T22:45:11Z (2 years ago)
From
Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>
H. Kumar (IITB), V. Swain (IITB), A. Salgundi (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed ZTF23aajfoed and ZTF23aajfilx detected by ZTF in localization region of the short GRB 230512A (Fermi GBM team, GCN 33778), with the 0.7m GROWTH-India Telescope (GIT). The observations started at 17:42:28 UT on 2023-05-12 for ZTF23aajfoed and at 17:08:25 for ZTF23aajfilx, roughly 11 hours after the Fermi GBM trigger. We obtained multiple 300s exposures in the g' and r' filters. We clearly detected the candidates at position reported by T. Ahumada et al., GCN 33784. The photometric results are follow as:
------------------------------------------------------------------------------------
Target | mjd (mid) | Filter | Total Exposure (s) | Magnitude (AB) |
-------------------------------------------------------------------------------------
ZTF23aajfoed | 60076.741640 | r' | 300 | 18.87 +/- 0.06 |
ZTF23aajfoed | 60076.745515 | g' | 300 | 18.84 +/- 0.07 |
ZTF23aajfilx | 60076.717906 | r' | 300 | 20.16 +/- 0.07 |
ZTF23aajfilx | 60076.745515 | g' | 300 | 20.23 +/- 0.07 |
-----------------------------------------------------------------------------------
A comparison of GIT and ZTF observations suggests that both the targets are not evolving rapidly, indicating that they are unlikely to be GRB afterglows. The magnitudes are 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 operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
GCN Circular 33785
Subject
GRB 230512A: Fermi GBM detection
Date
2023-05-12T22:33:49Z (2 years ago)
From
Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>
S. Bala (USRA), O.J. Roberts (USRA/NASA-MSFC), B. Mailyan (Florida Tech) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 06:27:45.00 UT on 12 May 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230512A (trigger 705565670 /230512269), which was also
detected by the Fermi/LAT (D. J. Maheso et al. 2023, GCN 33780).
The Fermi GBM Final Real-time Localization (GCN 33778) is consistent with the LAT position.
The angle from the Fermi LAT boresight at the GBM trigger time is 45 degrees.
The GBM light curve consists of multiple short peaks
with a duration (T90) of about 3 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+2.944 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.67 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 1344 +/- 69 keV
The event fluence (10-1000 keV) in this time interval is
(1.33 +/- 0.02)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.54 s in the 10-1000 keV band
is 16.8 +/- 0.3 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 1215 +/- 79 keV, alpha = -0.65 +/- 0.03 and beta = -2.7 +/- 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 33784
Subject
GRB 230512A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705565670)
Date
2023-05-12T20:21:39Z (2 years ago)
From
Tomas Ahumada at U. of Maryland <tahumada@astro.umd.edu>
Tomas Ahumada (CIT), Harsh Kumar (IITB), Viraj Karambelkar (CIT), Robert
Stein (CIT), Theophile du Laz (CIT), Igor Andreoni (UMD), Michael Coughlin
(UMN), Mansi Kasliwal (CIT), Simeon Reusch (DESY), Jannis Necker (DESY),
Shreya Anand (CIT), report on behalf of the ZTF collaboration:
We observed the localization region of the short bright GRB 230512A
(trigger 705565670, GCN 33778) detected by the Gamma-Ray Burst Monitor
(GBM) on the Fermi satellite with the Palomar 48 inch telescope equipped
with the 47 square degree Zwicky Transient Facility (ZTF; Bellm et al.,
2019; Graham et al., 2019) camera. ZTF covered 597.8 square degrees
corresponding to ~86% of the probability enclosed in the localization
region (GCN 33778), beginning 2 hours after the burst trigger time.
Exposures reached a median depth of 21 mag in the g-band and 20.9 mag in
the r-band.
Two sources were found within the 95% localization region, although all are
outside the 90% credible level. These are likely unrelated as they fall
outside the LAT localization circulated on GCN 33780:
+--------------+---------+----------+---------+------------+------------+------------+
| id | alias | ra | dec | mjd | mag
|filter |
|--------------+---------+----------+---------+------------|------------+------------|
| ZTF23aajfoed | AT 2023ibn | 295.8501 | 51.5420 | 60076.4041 | 18.89±0.08
| g |
| ZTF23aajfilx | AT 2023ibo | 267.5692 | 40.7678 | 60076.3839 | 20.22±0.19
| g |
+--------------+---------+----------+---------+------------+------------+------------+
ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC,
USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY,
Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan;
IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No
1440341.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski
(Duev et al. 2019). GROWTH India telescope is located at the Indian
Astronomical Observatory (Hanle), operated by the Indian Institute of
Astrophysics (IIA). GROWTH-India project is supported by SERB and
administered by IUSSTF, under grant number IUSSTF/PIRE
Program/GROWTH/2015-16 and IUCAA.
--
Tomás Ahumada (he/him)
Ph.D. Candidate
Department of Astronomy
University of Maryland, College Park
NASA <tomas.f.ahumdamena@nasa.gov> Goddard Space Flight Center, Code 661
B.Sc. Astronomy, Pontificia Universidad Católica de Chile
GCN Circular 33781
Subject
GRB 230512A: Tiled Swift observations
Date
2023-05-12T19:05:37Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
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 230512A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00111
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 33780
Subject
GRB 230512A: Fermi-LAT detection
Date
2023-05-12T18:34:10Z (2 years ago)
From
N. Di Lalla at Stanford University <niccolo.dilalla@stanford.edu>
D. J. Maheso (Johannesburg Univ.), N. Di Lalla (Stanford Univ.), Khalil T. (Johannesburg Univ.), E. Bissaldi (Politecnico and INFN Bari), N. Omodei (Stanford Univ.), D. Kocevski (NASA/MSFC) and D. Horan (IN2P3/CNRS) report on behalf of the Fermi-LAT Collaboration:
At 06:27:45.41 on May 12, 2023, Fermi-LAT detected high-energy emission from GRB 230512A, which was also detected by Fermi-GBM (trigger 705565670/230512269, GCN 33778) and AstroSat (GCN 33779).
The best LAT on-ground location is found to be
RA, Dec = 295.4, 38.4 (degrees, J2000)
with an error radius of 0.3 deg (90% containment, statistical error only).
This was 45 deg from the LAT boresight at the time of the trigger.
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 100 MeV - 1 GeV photon flux in the time interval 0-300 s after the GBM trigger is (1.0 ± 0.3) E-05 ph/cm2/s. The estimated integrated photon index above 100 MeV is -2.15 ± 0.3.
The highest-energy photon is a 1.7 GeV event with 99% probability which is observed 84 seconds after the GBM trigger.
A Swift ToO has been approved for this burst.
The Fermi-LAT point of contact for this burst is Dimakatso Maheso (d.j.maheso@gmail.com <mailto:xxxx@xxx.xxx>)
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 33779
Subject
GRB 230512A: AstroSat CZTI detection
Date
2023-05-12T14:20:03Z (2 years ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
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 GRB 230512A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 33778).
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 2023-05-12 06:27:47.85 UTC. The measured peak count rate associated with the burst is 2471 (+338, -103) counts/s above the background in the combined data of all quadrants, with a total of 3279 (+219, -231) counts. The local mean background count rate was 490 (+10, -12) counts/s. Using cumulative rates, we measure a T90 of 2.44 (+0.17, -0.13) s. In the preliminary analysis, we find 317 Compton events associated with this event.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-05-12 06:27:47.85 UTC. The measured peak count rate associated with the burst is 2735 (+109, -115) counts/s above the background in the combined data of all quadrants, with a total of 6183 (+356, -346) counts. The local mean background count rate was 1667 (+6, -9) counts/s. We measure a T90 of 2.82 (+2.02, -0.27) 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 33778
Subject
GRB 230512A: Fermi GBM Final Localization
Date
2023-05-12T11:59:08Z (2 years ago)
From
R. Hamburg at CNRS/IJCLab <rachel.k.hamburg@gmail.com>
The Fermi GBM team reports the detection of a Short Bright GRB.
At 06:27:45 UT on 12 May 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230512A (trigger 705565670/230512269).
The on-ground calculated location, using the Fermi GBM trigger data, is RA
= 277.62, Dec = +53.87 (J2000 degrees, equivalent to J2000 18h 30m, +53d
53'), with a statistical uncertainty of 1 degree.
The angle from the Fermi LAT boresight is 26 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230512269/quicklook/glg_skymap_all_bn230512269.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/bn230512269/quicklook/glg_healpix_all_bn230512269.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230512269/quicklook/glg_lc_medres34_bn230512269.gif