January 2025 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 36757] GRB 250101A: Nanshan/HMT optical observations
by GCN Circulars 01 Jan '25

01 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38755 SUBJECT: GRB 250101A: Nanshan/HMT optical observations DATE: 25/01/01 14:55:10 GMT FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn> Z.P. Zhu, S.Y. Fu, X. Liu, S.Q. Jiang, J. An, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report on behalf of a large collaboration: We observed the optical counterpart of GRB 250101A detected by Swift/BAT (Page et. al., GCN 38752), using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 13:24:51 UT on 2025-01-01, i.e., 121 s after the Swift/BAT trigger, and a series of unfiltered frames with different exposures were obtained. The optical counterpart (e.g., Page et. al., GCN 38752; Li et al., GCN 38753; Mohan et al., GCN 38754) is clearly detected in the individual frames, and the lightcurve shows an initial rise and then a continuous decay. We measured G ~ 18.3 mag at 30 mins post-burst, calibrated with GAIA-DR3 and not corrected for Galactic extinction. Observations are still ongoing. View this GCN Circular online at https://gcn.nasa.gov/circulars/38755. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36756] GRB 250101A : GIT optical detection
by GCN Circulars 01 Jan '25

01 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38754 SUBJECT: GRB 250101A : GIT optical detection DATE: 25/01/01 14:35:06 GMT FROM: V. Swain at IIT Bombay <vishwajeet.s(a)iitb.ac.in> T. Mohan, V. Swain, A.P. Saikia, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team: We observed the field of Swift GRB 250101A (Page et. al., GCN 38752) with 0.7m GROWTH-India Telescope (GIT) in r' filter. We started the observation at 2025-01-01 13:55:28 UT, i.e., 32.6 mins after the Swift Bat trigger. The source is detected at UVOT position and photometry result follows as: | JD (mid) | t-t0 (mins) | Filter | Exposure (s) | Mag (AB) | | ----------------- | ----------- |------- | ------------------ | -------------- | | 2460677.080185 | 34.6 | r' | 240 | 18.36 +/- 0.08 | More broadband observations are ongoing. Our result is consistent with GMG Optical Observation (Li et. al., GCN 38753) The measurement 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/. View this GCN Circular online at https://gcn.nasa.gov/circulars/38754. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36755] GRB 250101A: GMG Optical Observation
by GCN Circulars 01 Jan '25

01 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38753 SUBJECT: GRB 250101A: GMG Optical Observation DATE: 25/01/01 14:19:34 GMT FROM: Rui-Zhi Li at Yunnan Observatories, CAS <liruizhi(a)ynao.ac.cn> R.-Z. Li, B.-T. Wang, F.-F. Song, J. Mao, H. Lin and J.-M. Bai (YNAO, CAS) report: We observed the field of GRB 250101A (Page et al., GCN 38752, T0 at 2025-01-01T13:22:50) using the GMG-2.4m telescope at the Lijiang Observatory. The observation began at 2025-01-01T14:00:24, about 0.63 hours after the trigger. The optical counterpart of GRB 250101A, not visible in the Pan-STARRS1 r-band image, was (marginally/clearly) detected at the coordinates (J2000): RA = 02 28 16.50 DEC = +19 11 39.4 , with a positional uncertainty of 0.5" or better. The position is consistent with UVOT position (GCN 38752). The preliminary analysis results are shown as follows: +----------------+------------+----------+--------------+----------------+ | Tmid-T0 [hr] | Exp. [s] | Filter | Mag | 5-sigma U.L. | +================+============+==========+==============+================+ | 0.71 | 600 | r | 18.64 ± 0.01 | 22.2 | +----------------+------------+----------+--------------+----------------+ The given magnitudes are derived based on calibration against Pan-STARRS1 field stars, and are not corrected for the expected Galactic foreground extinction, corresponding to a reddening of E(B-V) = 0.1408 mag in the direction of the optical counterpart (Schlafly & Finkbeiner 2011). View this GCN Circular online at https://gcn.nasa.gov/circulars/38753. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36754] GRB 250101A: Swift detection of a burst with an optical counterpart
by GCN Circulars 01 Jan '25

01 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38752 SUBJECT: GRB 250101A: Swift detection of a burst with an optical counterpart DATE: 25/01/01 13:39:49 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> K. L. Page (U Leicester), R. Gupta (NASA GSFC), H. A. Krimm (NSF), A. Y. Lien (U Tampa) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 13:22:50 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250101A (trigger=1278305). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 37.061, +19.154 which is RA(J2000) = 02h 28m 15s Dec(J2000) = +19d 09' 14" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 25 sec. The peak count rate was ~400 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 13:24:57.4 UT, 127.4 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 37.06963, 19.19521 which is equivalent to: RA(J2000) = 02h 28m 16.71s Dec(J2000) = +19d 11' 42.8" with an uncertainty of 3.9 arcseconds (radius, 90% containment). This location is 151 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.44 x 10^21 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 132 seconds after the BAT trigger. There is a candidate afterglow in the list of sources generated on-board at RA(J2000) = 02:28:16.50 = 37.06873 DEC(J2000) = +19:11:39.9 = 19.19442 with a 90%-confidence error radius of about 1.10 arc sec. This position is 3.8 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.30. No correction has been made for the expected extinction corresponding to E(B-V) of 0.164. Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/38752. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36753] Swift GRB250101.56: Global MASTER-Net observations report
by GCN Circulars 01 Jan '25

01 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38751 SUBJECT: Swift GRB250101.56: Global MASTER-Net observations report DATE: 25/01/01 13:34:39 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity) D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the Swift GRB250101.56 (trigger No 1278305,02h 28m 14.64s , +19d 09m 14.4s, R=0.05) errorbox 35 sec after notice time and 86 sec after trigger time at 2025-01-01 13:24:16 UT, with upper limit up to 20.7 mag. The observations began at zenith distance = 32 deg. The sun altitude is -38.6 deg. The galactic latitude b = -38 deg., longitude l = 153 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2730214 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 96 | MASTER-Tunka | C | 20 | 19.8 | 121 | MASTER-Tunka | C | 70 | 20.5 | Coadd 120 | MASTER-Tunka | C | 20 | 19.9 | 148 | MASTER-Tunka | C | 30 | 20.1 | 182 | MASTER-Tunka | C | 30 | 20.1 | 227 | MASTER-Tunka | C | 120 | 20.7 | Coadd 220 | MASTER-Tunka | C | 40 | 20.2 | 269 | MASTER-Tunka | C | 50 | 20.2 | 327 | MASTER-Tunka | C | 60 | 20.3 | 396 | MASTER-Tunka | C | 70 | 20.4 | 480 | MASTER-Tunka | C | 90 | 20.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/38751. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36752] GRB 241217a/EP241217b: ATCA Radio Detection
by GCN Circulars 01 Jan '25

01 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38750 SUBJECT: GRB 241217a/EP241217b: ATCA Radio Detection DATE: 25/01/01 07:04:32 GMT FROM: Tao An at SHAO, CAS <antao(a)shao.ac.cn> Tao An, Yuanqi Liu (Shanghai Astronomical Observatory, China), Jinjun Geng, Xuefeng Wu (Purple Mountain Observatory, China) report on behalf of the EP radio follow-up team:  We report continued radio follow-up observations of GRB 241217A/EP241217b (Marius et al. GCN 38594; Zhou et al. GCN 38606) with the Australia Telescope Compact Array (ATCA), following our initial observations (GCN 38649). In our subsequent observation on December 24 (UT14:00-18:30), we detect significant radio emission (>6σ) at both 5.5 GHz and 9 GHz frequencies. After careful reanalysis of our first epoch data (December 20 UT13:00-18:00), we detect a 5σ radio source at 5.5 GHz, while the 9 GHz band shows no significant detection. Further ATCA observations are scheduled to monitor the temporal and spectral evolution of this source. We thank the CSIRO Space and Astronomy staff, in particular Jamie Stevens, for supporting these observations in a timely manner. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility which is funded by the Australian Government for operation as a National Facility managed by CSIRO. View this GCN Circular online at https://gcn.nasa.gov/circulars/38750. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36751] EP241217a: VLA Radio Detection
by GCN Circulars 01 Jan '25

01 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38749 SUBJECT: EP241217a: VLA Radio Detection  DATE: 25/01/01 07:00:59 GMT FROM: Tao An at SHAO, CAS <antao(a)shao.ac.cn> Tao An, Yuanqi Liu (Shanghai Astronomical Observatory, China), Jinjun Geng, Xuefeng Wu (Purple Mountain Observatory, China) report on behalf of the EP radio follow-up team:  We report VLA radio observations of EP241217a. Following the Einstein Probe (EP) detection (GCN 38586) and subsequent X-ray detections by Swift/XRT (GCN 38596, 38624), we conducted radio follow-up observations with the Karl G. Jansky Very Large Array (VLA). We detected a point radio source at the position reported by the EP/FXT and Swift/XRT on 2024 December 21 UT01:00. Data calibration used the VLA calibration and imaging pipeline in CASA 6.5.4.9. The preliminary analysis suggests a flux density of 20±6.6 microJy (at 3 GHz), 58±4 microJy (at 6 GHz) and 99.3±4.1 microJy at 10 GHz. We have obtained multi-band, multi-epoch VLA monitoring observation time and are conducting long-term monitoring of this interesting object. We thank the TAC and operations team of VLA for making these observations in a timely manner. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. View this GCN Circular online at https://gcn.nasa.gov/circulars/38749. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36750] LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
by GCN Circulars 01 Jan '25

01 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38748 SUBJECT: LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations DATE: 25/01/01 02:29:35 GMT FROM: Motoko Serino at Aoyama Gakuin U. <serino(a)phys.aoyama.ac.jp> M. Serino, S. Sugita, Y. Kawakubo, H. Hiramatsu, H. Nishikawa, Y. Kondo (AGU), H. Negoro, M. Nakajima, K. Takagi (Nihon U.), N. Kawai, T. Mihara, (RIKEN) report on behalf of the MAXI team: We examined MAXI/GSC all-sky X-ray images (2-20 keV) after compact binary merger candidate S241231du at 2024-12-31 13:16:46.194 UTC. At the trigger time of S241231du, the high-voltage of MAXI/GSC was on. The instantaneous field of view of GSC at the GW trigger time covered 4% of the 90% credible region of the bayestar sky map, in which we found no significant new X-ray source. The first one-orbit (92 min) scan observation with GSC after the event covered 90% of the 90% credible region of the bayestar skymap from 13:16:46 to 14:48:44 UTC (T0+0 to T0+5518 sec). No significant new source was found in the region in the one-orbit scan observation. A typical 1-sigma averaged upper limit obtained in one scan observation is 20 mCrab at 2-20 keV. If you require information about X-ray flux by MAXI/GSC at specific coordinates, please contact the submitter of this circular by email. View this GCN Circular online at https://gcn.nasa.gov/circulars/38748. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 36749] LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
by GCN Circulars 01 Jan '25

01 Jan '25

TITLE: GCN CIRCULAR NUMBER: 38747 SUBJECT: LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate DATE: 25/01/01 02:02:54 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 S250101k during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-01-01 01:12:05.047 UTC (GPS time: 1419729143.047). The candidate was found by the GstLAL [1] and MBTA [2] analysis pipelines. S250101k is an event of interest because its false alarm rate, as estimated by the online analysis, is 5.6e-08 Hz, or about one in 6 months. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S250101k After parameter estimation by RapidPE-RIFT [3], the classification of the GW signal, in order of descending probability, is BBH (88%), NSBH (8%), Terrestrial (4%), 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%. [4] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [4] 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,0, an initial localization generated by BAYESTAR [5], distributed via GCN notice about 27 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [5], distributed via GCN notice about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 1126 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 3057 +/- 892 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] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625 [2] Aubin et al. CQG 38, 095004 (2021) doi:10.1088/1361-6382/abe913 [3] Rose et al. (2022) arXiv:2201.05263 and Pankow et al. PRD 92, 023002 (2015) doi:10.1103/PhysRevD.92.023002 [4] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [5] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/38747. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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