TITLE: GCN CIRCULAR
NUMBER: 38815
SUBJECT: GRB 241228A: 1.3m DFOT upper limit
DATE: 25/01/04 05:40:01 GMT
FROM: Amit Kumar Ror at ARIES <mitturor77894(a)gmail.com>
Amit K. Ror, Anshika Gupta, Pranshu, Shashi B. Pandey, Kuntal Mishra
(ARIES) report:
We observed the field of GRB 241228A detected by Swift (Swift Observatory
Team, D'Elia et al. 2024, GCN 38681) with the 1.3m Devasthal Fast Optical
Telescope (DFOT), located at the Devasthal Observatory of the Aryabhatta
Research …
[View More]Institute of Observational Sciences (ARIES), India. The
observations were started on 2024-12-30 at 13:16:07 UT, i.e., ~ 2.38 days
after the Swift-BAT trigger. We have taken multiple frames with an exposure
time of 300 s in the R filter. We stacked the images after the alignment.
We could not detect the optical emission reported by Volnova et al. (2024,
GCN 38709) in our stacked image within the error box enhanced Swift-XRT
position (GCN 38683). We obtain the following 3-sigma upper limit in the
stacked image:
Date Start_UT T_start-T0 (days) Filter Exp time (s) Magnitude
=========================================================
2024-12-30 13:16:07 ~ 2.38 R 300s*12 >21.2
The non-detection of the burst is consistent with the upper limits reported
by Kuin et al. 2024, GCN 38685; Mohan et al. 2024, GCN 38689; Lipunov et
al. 2024, GCN 38693; Zhu et al. 2024, GCN 38703.
The magnitude is not corrected for the Galactic extinction in the direction
of the burst. Photometric calibration is performed using the standard stars
from the USNO-B1.0 catalogue. This circular may be cited.
View this GCN Circular online at https://gcn.nasa.gov/circulars/38815.
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TITLE: GCN CIRCULAR
NUMBER: 38814
SUBJECT: GRB 250103A: NOT spectroscopic redshift
DATE: 25/01/04 03:37:11 GMT
FROM: Zipei Zhu at NAOC <zpzhu(a)nao.cas.cn>
Z.P. Zhu, D. Xu (NAOC), D. B. Malesani (DAWN/NBI and Radboud Univ.), A. Saccardi (CEA/Irfu), K. Valeckas (NBI) report on behalf of a large collaboration:
We carried out spectroscopy of the optical counterpart (e.g., Li et al., GCN 38795; Qiu et al., GCN 38802; Xu et al., GCN 38808; Leonini et al., GCN 38811) of GRB 250103A …
[View More]detected by SVOM/ECLAIRs (Wang et al., GCN 38786) and Fermi/GBM (Trigg et al., GCN 38806), using the the ALFOSC instruments mounted on the Nordic Optical Telescope (NOT). Observations started at 21:49:26 UT on 2025-01-04, i.e., 11.88 hrs after the burst, consisted of 2 exposures of 1200 s each, and the spectra cover the wavelength range 3600 - 9000 AA.
The whole spectrum has a fairly low S/N, but absorption features are evident. From the detection of a Lya absorption feature at ~ 6088 AA and multiple absorption features, which interpreted as being due to Si II, C II, Si IV, C IV, Fe II, and Al II, we infer a common redshift of z = 4.01, fully consistent with the measurement from GTC (de Ugarte Postigo et al., GCN 38809). We conclude this is the redshift of the burst.
View this GCN Circular online at https://gcn.nasa.gov/circulars/38814.
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TITLE: GCN CIRCULAR
NUMBER: 38813
SUBJECT: GRB 250103B:SVOM/VT optical counterpart
DATE: 25/01/04 02:54:27 GMT
FROM: Liping Xin at NAOC, SVOM <xlp(a)nao.cas.cn>
SVOM/VT commissioning team: Y. L. Qiu, H. L. Li, L. P. Xin, C. Wu, X. H. Han, J. Wang, W. J. Xie, H. B. Cai, Y. Xu, Y. J. Xiao, P. P. Zhang, J. S. Deng, L. Lan, X. M. Lu, R. S. Zhang, Z. H. Yao (NAOC), J. Zhang, L. J. Dan, G. Y. Zou, C. J. Wang, Y. F. Du, C. Huang (XIOPM),T. Bouchet, D. Turpin (CEA)
SVOM JSWG: Jian-Yan …
[View More]Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (IHEP), Stéphane Basa (LAM), Arnaud Claret (CEA), Zi-Gao Dai (USTC), Frédéric Daigne (IAP), Jin-Song Deng (NAOC), Olivier Godet (IRAP), Andrea Goldwurm (APC), Diego Götz (CEA), Xu-Hui Han (NAOC), Cyril Lachaud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs.Paris), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Shao-Lin Xiong (IHEP), Bing Zhang (UNLV)
report on behalf of the SVOM team:
The SVOM/VT conducted a ToO follow-up observations for GRB 250103B triggered by both Swift(R. A. J. Eyles-Ferris, GCN 38796) and SVOM (T. Bouchet, GCN 38797) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously, from 2.467 hours to 7.573 hours after the burst.
An uncatalogued fading source was clearly detected within the errorbox of XRT (R. A. J. Eyles-Ferris, GCN 38796) in both VT_B and VT_R stacked images, compared to DESI DR10 catalog. The brightness of the source was estimated to be VT_B=22.1+/-0.1 mag and VT_R=21.8+/-0.1 mag in AB magnitude at the mid time of 2.79 hours post the burst, with a total exposure time of 23*100 seconds.
The source is located at RA, Dec = 54.66373, -33.74927 deg, which is equivalent to:
RA (J2000) : 03:38:39.30
Dec (J2000): -33:44:57.4
with an uncertainty of 0.2 arcsec.
We proposed that the source is the counterpart for the gamma-ray burst.
More deep follow-ups are encouraged.
The magnitudes give above are not corrected for the expected Galactic foreground extinction, corresponding to a reddening of E(B-V) = 0.0067 mag in the direction of the optical counterpart (Schlafly & Finkbeiner 2011).
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC),CAS.
View this GCN Circular online at https://gcn.nasa.gov/circulars/38813.
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TITLE: GCN CIRCULAR
NUMBER: 38812
SUBJECT: LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
DATE: 25/01/04 02:33:23 GMT
FROM: JeongCho Kim at Seoul National University <jeongcho.kim(a)ligo.org>
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We identified the compact binary merger candidate S250104v during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (…
[View More]L1), and Virgo Observatory (V1) at 2025-01-04 01:51:22.329 UTC (GPS time: 1419990700.329). The candidate was found by the CWB [1], cWB-BBH [2], GstLAL [3], MBTA [4], PyCBC Live [5], and SPIIR [6] analysis pipelines.
S250104v is an event of interest because its false alarm rate, as estimated by the online analysis, is 9.5e-13 Hz, or about one in 1e5 years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S250104v
The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%).
Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [7] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [7] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%.
Two sky maps are available at this time and can be retrieved from the GraceDB event page:
* bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [8], distributed via GCN notice about 29 seconds after the candidate event time.
* bayestar.multiorder.fits,2, an initial localization generated by BAYESTAR [8], distributed via GCN notice about 5 minutes after the candidate event time.
The preferred sky map at this time is bayestar.multiorder.fits,2. For the bayestar.multiorder.fits,2 sky map, the 90% credible region is 1621 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 5423 +/- 1429 Mpc (a posteriori mean +/- standard deviation).
For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/.
[1] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004
[2] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018
[3] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625
[4] Aubin et al. CQG 38, 095004 (2021) doi:10.1088/1361-6382/abe913
[5] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a
[6] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023
[7] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe
[8] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013
View this GCN Circular online at https://gcn.nasa.gov/circulars/38812.
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TITLE: GCN CIRCULAR
NUMBER: 38811
SUBJECT: GRB 250103A: Montarrenti Observatory optical detection
DATE: 25/01/04 02:03:31 GMT
FROM: Simone Leonini at Montarrenti Observatory (Siena, Italy) <s.leonini(a)iol.it>
S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy, part of UAI/SSV-GRB section), M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy) and K. Kalinowski (Aarhus University, …
[View More]Department of Physics and Astronomy) report:
We observed the field of SVOM triggered GRB 250103A (Wang et al., GCN 38786, GCN 38787) with the automated and remoted 0.53m Ritchey-Chretien telescope at Montarrenti Observatory (Siena, Italy, IAU code C88).
The observations were started at 2025-01-03 17:58:28 UT (approximately 8 hours after burst) stacking a set of Ic-band CCD images. Observations were performed under thin cloud cover in the first part of the night.
The OT was barely detected (S/N =1.7) at the following position:
RA (J2000.0) 01h 28m 15.28s +/-0.05
Decl. (J2000.0) -05° 03' 06.59" +/-0.12
Preliminary photometry was obtained using nearby PanSTARRS stars as follows:
Observation Mid-Time T-T0 (hr) Exposure Filter Mag. Err. UL (3-sigma)
2025-01-03 18:55:32 UT 8.98 111x40s Ic 20.7 S/N =1.7 >20.4
Magnitude was calibrated with the nearby PanSTARRS stars converted using Lupton (2005) equations. No correction for galactic dust extinction was applied.
Our observations are consistent with other already reported (Li et al., GCN 38795; Qiu et al., GCN 38802; Xu et al., GCN 38808).
View this GCN Circular online at https://gcn.nasa.gov/circulars/38811.
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TITLE: GCN CIRCULAR
NUMBER: 38810
SUBJECT: GRB 250101A: further LCOGT optical afterglow observations
DATE: 25/01/04 01:15:20 GMT
FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf(a)iac.es>
C. Méndez-Lapido, B. Armas-Chinea, F. Dobrindt, P. Escudero-Coca, G. Fernández-Rodríguez, Á. García Lozano, A. Huertas Ferrer, I. Ortega-Casas, M. Torreiro Martínez, G. Villa (ULL), S.R. Berlanas, F. Poidevin, and I. Pérez-Fournon (IAC and ULL)
We report on further …
[View More]optical imaging of the field of GRB 250101A, discovered by Swift BAT (Page et al., GCN #38752), with one of the two Las Cumbres Observatory global telescope network (LCOGT) 40-cm telescopes located at the LCOGT node at the Cerro Tololo Inter-American Observatory (CTIO, Chile).
The observation, a single 600-sec exposure in the SDSS r' filter, started on 2025-01-02 01:24:03 UT, i.e. ~ 12.02 hr after the Swift BAT trigger. We detect the optical afterglow at a position consistent with the Swift UVOT position reported by Page et al. (GCN #38752). We measure a magnitude of r' = 20.12 +/- 0.18 calibrated against PanSTARRS DR1 stars and not corrected for Galactic extinction.
This result is consistent with other reports: Li et al. (GCN 38753), Mohan et al. (GCN 38754), Zhu et al. (GCN 38755); Budnev et al. (GCN 38756), Wu et al. (GCN 38758), Moskvitin and Spiridonova (GCN 38762), Odeh and Guessoum (GCN 38763), Hu et al. (GCN 38764), Moskvitin et al. (GCN 38765), D'Avino and Izzo (GCN 38768), Escudero-Coca et al (GCN 38769), Leonini et al. (GCN 38771), Zhang et al. (GCN 38774), Siegel and Page (GCN 38775), Komesh et al. (GCN 38777), Ghosh et al. (GCN 38779), Moskvitin et al. (GCN 38780), Komesh et al. (GCN 38790), and Bochenek and Perley (GCN 38798).
The spectroscopic redshift has been measured by Zhu et al., z = 2.49 (GCN 38759) and Li et al., z ~ 2.481 (GCN 38776).
These results are based on observations made with the Las Cumbres Observatory’s education network
telescopes that were upgraded through generous support from the Gordon and Betty Moore Foundation
and are part of a course on Astrophysical Techniques of the Master in Astrophysics of the Universidad
de La Laguna, Tenerife, Spain (LCOGT observing programme IAC2024B-010, ULL-ASTRO-MASTER).
View this GCN Circular online at https://gcn.nasa.gov/circulars/38810.
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TITLE: GCN CIRCULAR
NUMBER: 38809
SUBJECT: GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
DATE: 25/01/03 23:35:51 GMT
FROM: Antonio de Ugarte Postigo at LAM/OCA, CNRS <deugarte(a)oca.eu>
A. de Ugarte Postigo (CNRS, OCA and LAM), D. B. Malesani (DAWN/NBI and Radboud Univ.), C. C. Thoene (ASU-CAS, AbAO), J. F. Agui Fernandez (CAHA), N. R. Tanvir (Univ. Leicester), L. Izzo (INAF/OACn and DARK/NBI), J. P. U. Fynbo (DAWN/NBI), S. Geier (GTC), G. Lombardi (GTC), A. Martin-Carrillo (UCD),…
[View More] N. A. Rakotondrainibe (LAM), Riccardo Scarpa (GTC) and Alvaro Tejero (GTC), report:
We observed the optical counterpart of GRB 250103A (Wang et al. GCN 38786, Li et al. GCN 38795, Qiu et al. GCN 38802, Trigg et al. GCN 38806, Xu et al. GCN 38808) with OSIRIS+, mounted on the 10.4 m GTC, at Roque de los Muchachos Observatory, in the island of La Palma (Spain). The observation started at 2025-01-03T22:03:11.011 UT (12.11 hr after the burst) consisted of an r-band acquisition followed by a single 1200 s spectrum with grism R1000B, covering the range between 3600 and 7800 AA. Although the planned observation was longer, weather and technical issues prevented us from completing the planned observation.
In a preliminary reduction, the spectrum shows a red trace with strong features that we identify as being due to the Lyman-alpha forest, a broad damped Lyman-alpha feature, and strong lines of SiII, SiII*, SiIV, OI, CII, CIV, amongst others, at a common redshift of 4.01. Further analysis is ongoing.
The underlying galaxy mentioned by Xu et al. (GCN 38808) has AB magnitudes in the Legacy survey of g=24.55, r=23.16, i=22.77, z=22.52. We note that this photometry does show a break in the g-band, which would be consistent with the Lyman break at z = 4. However, if this object is indeed the host galaxy, it would have an extraordinary luminosity at z=4.01, with an absolute magnitude M(UV) ~ -23 mag.
View this GCN Circular online at https://gcn.nasa.gov/circulars/38809.
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TITLE: GCN CIRCULAR
NUMBER: 38808
SUBJECT: GRB 250103A: NOT optical observations
DATE: 25/01/03 23:14:19 GMT
FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani(a)astro.ru.nl>
D. Xu (NAOC), Z. P. Zhu (NAOC), D. B. Malesani (DAWN/NBI and Radboud Univ.), L. Izzo (INAF/OACn), A. de Ugarte Postigo (CNRS, OCA and LAM), A. Saccardi (CEA/Irfu), K. Valeckas (NBI), report on behalf of a larger collaboration:
We observed the optical counterpart (Li et al., GCN 38795; Qiu …
[View More]et al., GCN 38802) of the SVOM GRB 250103A (Wang et al., GCN 38786, 38787), using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Two observations by 200 s each were secured in the i band, with a mean time 2025 Jan 3.90 UT (8.16 hr after the GRB).
The optical counterpart is well detected, with an AB magnitude i = 21.14 +- 0.04, calibrated against nearby objects from the Pan-STARRS catalog.
We note that a relatively bright object (i ~ 22.8) is detected in the Legacy survey directly underlying the position of the optical afterglow.
View this GCN Circular online at https://gcn.nasa.gov/circulars/38808.
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TITLE: GCN CIRCULAR
NUMBER: 38807
SUBJECT: GRB 250103A: TSHAO optical upper limit
DATE: 25/01/03 22:04:21 GMT
FROM: Alexei Pozanenko at IKI, Moscow <grb.alex(a)gmail.com>
I. Reva (FAI), A. Pozanenko (IKI), A. Volnova (IKI), N. Pankov (HSE, IKI)
report on behalf of GRB IKI FuN:
We observed the field of GRB 250103A (Wang et al., GCN 38786) which also
triggered GBM/Fermi (Trigg et al., GCN 38806) with Zeiss-1000 telescope of
THSAO observatory in R-filter starting on 2025-01-03 (UT)…
[View More] 16:12:14.05. In a
stacked image we do not detect the optical afterglow (Li et al., GCN 38795;
SVOM/VT commissioning team, GCN 38802), and which is consistent with non
detection of the afterglow (SVOM/C-GFT team, GCN 38791; Starling et al.,
GCN 38792).
Preliminary photometry of the field is the following
Date UT start t-T0 Filter Exp. OT Err UL(3sigma)
mid, days
2025-01-03 16:12:14 0.26231 R 11*120 n/d n/d 19.0
The photometry is based on nearby USNO-B1.0 (R2) stars.
View this GCN Circular online at https://gcn.nasa.gov/circulars/38807.
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TITLE: GCN CIRCULAR
NUMBER: 38806
SUBJECT: GRB 250103A: Fermi GBM Observation
DATE: 25/01/03 21:19:29 GMT
FROM: atrigg2(a)lsu.edu
A. C. Trigg (LSU), U. Pathak (IITB) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 09:57:46.56 UT on 03 January 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 250103A (trigger 757591071/250103415).
which was also detected by SVOM (Y. Wang et al. 2025, GCN 38787).
The Fermi GBM on-ground location is consistent with …
[View More]the SVOM/ECLAIRs position.
The angle from the Fermi LAT boresight is 28 degrees.
The GBM light curve an initial emission followed by two smaller peaks with a duration (T90)
of about 118 s (50-300 keV). The time-averaged spectrum
from T0-7.6 to T0+112.3 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.75 +/- 0.09 and the cutoff energy,
parameterized as Epeak, is 33 +/- 5 keV.
The event fluence (10-1000 keV) in this time interval is
(5.5 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.3 s in the 10-1000 keV band is 2.8 +/- 0.2 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 32 +/- 4 keV, alpha = -1.70+/- 0.13 and beta = -2.65 +/- 0.38.
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/"
View this GCN Circular online at https://gcn.nasa.gov/circulars/38806.
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