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

[vsnet-grb-info 37176] LIGO/Virgo/KAGRA S250205ee: Updated Sky localization and Source Classification
by GCN Circulars 06 Feb '25

06 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39167 SUBJECT: LIGO/Virgo/KAGRA S250205ee: Updated Sky localization and Source Classification DATE: 25/02/06 10:35:25 GMT FROM: Divyajyoti NLN <divyajyoti.nln(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S250205ee (GCN Circular 39155). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250205ee After parameter estimation by RapidPE-RIFT [2], the updated classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%). For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 1574 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2493 +/- 889 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] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. (2023) arXiv:2307.13380 [2] Rose et al. (2022) arXiv:2201.05263 and Pankow et al. PRD 92, 023002 (2015) doi:10.1103/PhysRevD.92.023002 View this GCN Circular online at https://gcn.nasa.gov/circulars/39167. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37175] EP250205a/GRB 250205A: correction to the source localization
by GCN Circulars 06 Feb '25

06 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39166 SUBJECT: EP250205a/GRB 250205A: correction to the source localization DATE: 25/02/06 10:07:31 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Z. Y. Liu (USTC), M. H. Zhang, M. J. Liu, H. N. Yang, W. Yuan (NAO, CAS) report on behalf of the Einstein Probe team The EP-FXT observation source localization given in GCN 39165 is incorrect. The correct source localization should be R.A. = 113.5107, DEC = 32.3718 (J2000). We apologize for the mistake. View this GCN Circular online at https://gcn.nasa.gov/circulars/39166. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37174] EP250205a/GRB 250205A: Einstein Probe observation
by GCN Circulars 06 Feb '25

06 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39165 SUBJECT: EP250205a/GRB 250205A: Einstein Probe observation DATE: 25/02/06 09:14:37 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Z. Y. Liu (USTC), M. H. Zhang, M. J. Liu, H. N. Yang, W. Yuan (NAO, CAS) report on behalf of the Einstein Probe team We report on the detection of an X-ray transient, designated EP250205a, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, which triggered the on-board processing unit at 2025-02-05 21:32:08 (UTC) (trigger ID: 01709131283). The source position is R.A. = 113.522 deg, DEC = 32.363 deg (J2000) with an uncertainty of about 2.5 arcmin (radius, 90% C.L. statistical and systematic). An autonomous follow-up observation of EP250205a was performed by the Follow-up X-ray Telescope (FXT) on board EP, 256s after the WXT trigger. An uncatalogued X-ray source was detected at R.A. = 113.509 deg, DEC = 32.373 deg (J2000) with an uncertainty of less than 10 arcsec (radius, 90% C.L. statistical and systematic), consistent with the WXT position of EP250205a. The 0.5-4.0 keV WXT spectrum can be fitted with an absorbed power law with a fixed Galactic absorption with column density 4.4 x 10^20 cm^-2 and an intrinsic absorber with a redshift of 3.55. The fitted equivalent hydrogen column density of the intrinsic absorber is 6.5(+9.8/-6.5) x 10^22 cm^-2, the photon index 2.5(+1.7/-1.2), and the unabsorbed 0.5-4 keV flux 4.2 (+1.1/-1.1) x 10^-10 erg/s/cm^2. The average 0.5-10 keV spectrum of the follow-up observation obtained by EP-FXT can be fitted with an absorbed power law with a photon index of 2.82 (+0.06/-0.04) (with a galactic column density fixed at 4.4 x 10^20 cm^-2), yielding an average unabsorbed 0.5-10 keV flux of 3.65 (+0.07/-0.09) x 10^-11 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. EP250205a is spatially and temporally consistent with GRB 250205A (Saccardi et al. GCN 39154) at a redshift of 3.55 (de Ugarte Postigo et al. GCN 39160). EP250205a was first detected by WXT at 2025-02-05T21:31:28 (UTC), about 410 seconds after the SVOM/ECLAIRs trigger time (2025-02-05T21:24:38), due to Earth obscuration of the WXT FoV from 2025-02-05T20:26:42 to 2025-02-05T21:31:28. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES. View this GCN Circular online at https://gcn.nasa.gov/circulars/39165. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37173] GRB 250127C: SVOM/GRM observation of a burst
by GCN Circulars 06 Feb '25

06 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39164 SUBJECT: GRB 250127C: SVOM/GRM observation of a burst DATE: 25/02/06 07:00:22 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Jean-Luc Atteia (IRAP), Stéphane Schanne (CEA), Frédéric Piron (LUPM) report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a long burst GRB 250127C (SVOM trigger reference: sb25012702) at 2025-01-27T05:34:47.500 UTC (T0). With the event-by-event data downloaded through the X-band ground station, the GRM light curve of 15 to 600 keV shows that this burst consists of multi-pulses with a T90 of 28.6 +2.7/-9.9 s. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250127C.png The SVOM/GRM on-ground localization of this burst is (J2000): RA: 274.5 deg DEC: 25.0 deg Error: 1.94 deg (1sigma, statistical only) We caution that the calibration of SVOM/GRM is undergoing and this localization is subject to systematic errors. In addition, the position of this burst, as determined by GRM, is located at about 159 degrees from the SVOM optical axis, and outside the ECLAIRs field of view. This burst was detected by the Count-Rate Trigger onboard ECLAIRs, as an increase in counts over background, but it was not localized by the coded-mask imaging process, which confirms that the burst occurred outside the ECLAIRs field of view. 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. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM/GRM point of contact for this burst is: Chen-Wei Wang (IHEP) (cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/39164. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37172] GRB 250204B: SVOM/GRM observation of a likely short burst
by GCN Circulars 06 Feb '25

06 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39163 SUBJECT: GRB 250204B: SVOM/GRM observation of a likely short burst DATE: 25/02/06 06:08:28 GMT FROM: yqzhang_cl(a)163.com SVOM/GRM team: Yan-Qiu Zhang, Wen-Jun Tan, Chen-Wei Wang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Nicolas Dagoneau(CEA), Maria-GraziaBernardini (INAF-OAB), Jean-Luc Atteia (IRAP) report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a likely short burst GRB 250204B (sb25020402) at 2025-02-04T06:41:14.100 UTC (T0), which was also observed by Fermi/GBM (Fermi GBM team, GCN #39141) and AstroSat CZTI (A. Dasgupta et al., GCN #39142). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 2.92 +/- 0.08 s in the 15-300 keV band. In addition, the position of this burst, as determined by Fermi/GBM (GCN #39141, RA: 2.35 deg, DEC: 29.70 deg, Error: 2.80 deg), is located at about 137 degrees from the SVOM optical axis, and outside the ECLAIRs field of view. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250204B.png 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. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM/GRM point of contact for this burst is: Yan-Qiu Zhang (IHEP) (zhangyanqiu(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/39163. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37171] GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
by GCN Circulars 06 Feb '25

06 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39162 SUBJECT: GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection DATE: 25/02/06 05:06:58 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah Antier (OCA), Jean-Luc Atteia (IRAP), Rosa L. Becerra (Università degli Studi di Roma Tor Vergata), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Jean-Grégoire Ducoin (CPPM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), and Benjamin Schneider (LAM) report: We imaged the field of the SVOM/ECLAIRs GRB 250205A (Saccardi et al., GCN Circ. 39154) with the DDRAGO wide-field camera on the COLIBRÍ (SVOM/F-GFT) telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed from 2025-02-06 03:01 to 04:48 UTC, with a midpoint of 6.34 hours after the event, and obtained 3840 seconds of exposure in the r filter in good weather conditions. The data were reduced and stacked using custom software and then calibrated against the PS1 catalog and analysed using STDPipe (Karpov 2021). We detect the afterglow (Gompertz et al., GCN Circ. 39156, and Schneider & Adami, GCN Circ. 39157) with r = 22.89 +/- 0.11 This magnitude is not corrected for Galactic extinction. Our measurement is significantly fainter than the earlier r magnitudes reported by Gompertz et al. (GCN Circ. 39156), Schneider & Adami (GCN Circ. 39157), Palmerio et al. (GCN Circ. 39159), and de Ugarte Postigo et al. (GCN Circ. 39160), confirming that this is the afterglow. Compared to the magnitude reported by de Ugarte Postigo et al., our measurement implies a temporal index of -0.80 +/- 0.08 between 1.76 and 6.34 hours. Further observations are planned. We warmly thank the COLIBRÍ and DDRAGO engineering teams and the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/39162. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37170] GRB 250205A: Swift/XRT detection
by GCN Circulars 06 Feb '25

06 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39161 SUBJECT: GRB 250205A: Swift/XRT detection DATE: 25/02/06 00:52:30 GMT FROM: Jamie Kennea at Penn State <jak51(a)psu.edu> J. A. Kennea (PSU), B. Sbarufatti (INAF-OAB) and P. A. Evans (Leicester) report on behalf of the Swift/XRT team: At 22:38:21UT Swift began a target of opportunity observation of GRB 250205A (GCN #39154), approximately 74 minutes after the trigger. We detect a bright previously uncatalogued X-ray source at the following coordinates: RA/Dec(J2000) = 113.51144, 32.37196, which is equivalent to: RA (J2000): 07h 34m 02.75s, Dec (J2000): +32d 22' 19.1", with an estimated error of 3.8 arc-seconds radius (90% confidence). This position lies 69 arc-seconds from the SVOM/MXT position reported in GCN #39154, and 1.7 arc-seconds from the SVOM.VT optical counterpart (GCN #39159). The mean flux during the 1.4 ks XRT observation was 4.9 (±0.4) x 10^-12 erg cm^-2 s^-1 (0.3-10 keV). Further observations of GRB 250205A with Swift are planned. View this GCN Circular online at https://gcn.nasa.gov/circulars/39161. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37169] GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
by GCN Circulars 06 Feb '25

06 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39160 SUBJECT: GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55 DATE: 25/02/06 00:28:38 GMT FROM: Antonio de Ugarte Postigo at LAM/OCA, CNRS <deugarte(a)oca.eu> A. de Ugarte Postigo (LAM), D. B. Malesani (DAWN/NBI and Radboud Univ.), A. Martin-Carrillo (UCD), C. C. Thoene (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), N. A. Rakotondrainibe (LAM), A. M. Garcia Rodriguez (GTC), D. González González (GTC) report, We have observed the counterpart of GRB 250205A (Saccardi et al. GCN 39154, also detected by EP as trigger id 01709131283), also discovered in parallel by Gompertz et al. (GCN 39156) and Schneider et al. (GCN 39157) and detected by SVOM/VT (Palmerio et al. GCN 39159), with OSIRIS+ on the 10.4 m GTC, located at the Roque de los Muchachos Observatory in the island of La Palma (Spain). Our observation consisted of a 30 s acquisition in r-band followed by 4x900s of spectroscopy using grism R1000B, which covers the spectral range between 3600 and 7800 AA. The optical counterpart is well detected in the acquisition obtained at 23:10:36 UT (mean epoch 1.7661 hrs after the burst) with an r-band AB magnitude of 21.78 +/- 0.06 mag, as compared with 4 field stars from the Sloan catalogue. The spectra show a faint trace with clear absorption features. In a preliminary reduction, we identify features of Ly-alpha, SII, SiII, SiII*, OI, CII, SiIV, CIV, FeII, FeII* at a common redshift of 3.55, which we identify as the redshift of the GRB. Further analysis is ongoing. View this GCN Circular online at https://gcn.nasa.gov/circulars/39160. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37168] GRB250205A: SVOM/VT optical afterglow detection
by GCN Circulars 05 Feb '25

05 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39159 SUBJECT: GRB250205A: SVOM/VT optical afterglow detection DATE: 25/02/05 23:50:19 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> GRB 250205A: SVOM/VT optical counterpart confirmation J. T. Palmerio (CEA), S. Vergani (Obs.Paris), L.P. Xin, Y. L. Qiu (NAOC), A. Saccardi (CEA), H.L. Li., C. Wu, Z.H. Yao, Y.N. Ma, X.H. Han, H.B. Cai, J.Y. Wei (NAOC), report on behalf of the SVOM team: After the trigger by SVOM/ECLAIRs at 2025-02-05T21:24:38 UTC (Tb), SVOM performed an automatic slew on the burst. The VT observing time reported in (Saccardi et al. GCN 39154) is incorrect, rather SVOM/VT began observing the field at 2025-02-05T21:32:08, 449 seconds after the SVOM trigger, in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. An uncatalogued source was detected within the error box of SVOM/MXT (Saccardi et al. GCN 39154) using the VT VHF pipeline at ra=113.51107, dec=32.37187 (J2000), corresponding to: RA (J2000) = 07h34m02.7s Dec (J2000) = +32d22m18.7s with an uncertainty of 1 arcsec. consistent with the optical afterglow reported by Gompertz et al. (GCN 39156) and Schneider et al. (GCN 39157). The source was detected in both VT_R and VT_B, though the presence of light bloom from a bright source in the image prevents the determination of the VT_R magnitude from the VHF pipeline. The source was fading between the first 2 VT observing sequences, the magnitudes are given below: mag(AB) VT_B | mag err | mid-observing time since trigger (minutes) 20.91 | 0.06 | 8.75 21.18 | 0.05 | 12.5 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/39159. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37167] GRB 250205A: GOTO optical upper limits
by GCN Circulars 05 Feb '25

05 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39158 SUBJECT: GRB 250205A: GOTO optical upper limits DATE: 25/02/05 23:30:43 GMT FROM: Ben Gompertz at U of Birmingham <b.gompertz(a)bham.ac.uk> B. P. Gompertz, S. Belkin, D. O'Neill, G. Ramsay, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, F. Jimenez-Ibarra, A. Kumar, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, E. Pall'e and D. Pollacco report on behalf of the GOTO collaboration: We report on observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to GRB 250205A, detected by EP and SVOM (Saccardi et al., GCN 39154). Targeted observations were performed by GOTO-North (La Palma) at 21:43:59 on 2025-02-05 (19 minutes after the ECLAIRs trigger time). The observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. The optical counterpart reported by Gompertz et al. (GCN 39156) and Schneider et al. (GCN 39157) is not detected to a 3-sigma limiting AB magnitude of L > 19.7 mags. Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/39158. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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