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

[vsnet-grb-info 37416] IceCube-250207A: MASTER flaring blazar QSOJ0854+2006
by GCN Circulars 21 Feb '25

21 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39405 SUBJECT: IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 DATE: 25/02/21 11:20:59 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> with Zhirkov effect K. Labzina, K.Zhirkov, V.Lipunov, E.Gorbovskoy, G.Antipov, D.Vlasenko, A.Kuznetsov, N.Tyurina, P.Balanutsa, A.Chasovnikov, D.Kuvshinov, V.Topolev,Ya.Kechin,Yu.Tselik, K.Minkina (Lomonosov Moscow State University, SAI, Physics Department), O.Gress, N.… [View More]Budnev, O.Ershova (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), D.Buckley (SAAO), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), 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) MASTER600-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University; Lipunov, Kornilov, Gorbovskoy, Tiurina & Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591, pp.http://www.pereplet.ru/lipunov/625.html#625) started IceCube-250207A (IceCube GCN#39203)of the Ice Cube Alert 250207.09 error box ~11h after trigger time at 2025-02-07 13:53:05 UT, with upper limit up to 19.2 mag. (see cover map: https://master.sai.msu.ru/site/master2/observ.php?id=2770114) We analyzed MASTER archive images since 2010 of the source, that can be related with this event. Global MASTER Net detected QSOJ0854+2006 inside 1 sigma. QSOJ0854+2006 (https://simbad.u-strasbg.fr/simbad/sim-coo) fading to 16.6m during last nights observations. Fortunately, data from the ATLAS network (Tonry et al., 2018, PASP, 13, 164505) are available, which show that ~24 hours before the neutrino alert (05.13 feb 2025.) the blazar QSOJ0854+2006 was at its local standard brightness, it was 1 magnitude brighter: 15.1 . After a few days, the blazar returned to its original bright state. Thus, we report the observation of an Zhirkov effect discovered earlier (The Astrophysical Journal Letters, 896, L19, 2020) . The MASTER archive light curve from 2010 year is available at http://www.pereplet.ru/lipunov/images/ATbbo_galaxy_arhive_midi.jpg View this GCN Circular online at https://gcn.nasa.gov/circulars/39405. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37415] GRB 250221A: Enhanced Swift-XRT position
by GCN Circulars 21 Feb '25

21 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39404 SUBJECT: GRB 250221A: Enhanced Swift-XRT position DATE: 25/02/21 10:38:49 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 1504 s of XRT Photon Counting mode data and 3 UVOT images for GRB 250221A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the … [View More]

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[vsnet-grb-info 37414] LIGO/Virgo/KAGRA S250221eb: Retraction of GW compact binary merger candidate
by GCN Circulars 21 Feb '25

21 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39403 SUBJECT: LIGO/Virgo/KAGRA S250221eb: Retraction of GW compact binary merger candidate DATE: 25/02/21 10:30:20 GMT FROM: Lorenzo Lunghini <lorenzo.lunghini(a)na.infn.it> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: The trigger S250221eb is no longer considered to be a candidate of interest: there was a transient noise glitch in the LIGO Hanford detector. View this GCN Circular online at https:… [View More]

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[vsnet-grb-info 37413] EP250220a: 1.6m Mephisto observations
by GCN Circulars 21 Feb '25

21 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39402 SUBJECT: EP250220a: 1.6m Mephisto observations DATE: 25/02/21 09:36:39 GMT FROM: Brajesh Kumar at SWIFAR, YNU <brajesh(a)ynu.edu.cn> Helong Guo, Guowang Du, Xinlei Chen, Xiangkun Liu, Xiaotong Chen, Yiheng Xie, Brajesh Kumar, Yuan Fang, Edoardo P. Lagioia, Yu Pan, Xingzhu Zou, Xiaowei Liu (all SWIFAR, YNU) report on behalf of the Mephisto Team: The field of EP250220a detected by EP Team (Wang et al., GCN 39387) was observed with the 1.6m Multi-… [View More]

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[vsnet-grb-info 37412] EP250220a: Liverpool Telescope optical upper limits
by GCN Circulars 21 Feb '25

21 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39401 SUBJECT: EP250220a: Liverpool Telescope optical upper limits DATE: 25/02/21 09:31:44 GMT FROM: Rob Eyles-Ferris at U of Leicester <raje1(a)leicester.ac.uk> R. A. J. Eyles-Ferris, P. T. O’Brien and R. L. C. Starling (U of Leicester) report: We observed the field of the X-ray transient EP250220a (Wang et al., GCN 39387) with the 2m Liverpool Telescope using the IO:O instrument. We obtained 4x100s exposures in the SDSS g’ filter starting at 2025-… [View More]

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[vsnet-grb-info 37411] EP250220a: Optical upper limit with Kinder observations
by GCN Circulars 21 Feb '25

21 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39400 SUBJECT: EP250220a: Optical upper limit with Kinder observations DATE: 25/02/21 08:46:24 GMT FROM: Janet Chen at National Central University <janetstars(a)gmail.com> L. L. Fan (HNAS), A. Aryan (NCU), A. K. H. Kong (NTHU), T.-W. Chen, W.-J. Hou (both NCU), J. Gillanders (Oxford), S. J. Smartt (Oxford/QUB), Y. J. Yang, A. Sankar. K, Y.-C. Pan, C.-C. Ngeow, M.-H. Lee, H.-C. Lin, C.-H. Lai, H.-Y. Hsiao, C.-S. Lin, J.-K. Guo (all NCU), S. Yang, Z. N. … [View More]Wang, G. H. Sun (all HNAS), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, T. Moore, K. W. Smith, C. Angus, A. Aamer (all QUB), A. Schultz and M. Huber (both IfA, Hawaii) report: We observed the field of the fast X-ray transient EP250220a (Wang et al., GCN 39387) using the 1m LOT at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen & Yang et al. 2024, arXiv:2406.09270). The first LOT epoch of observations started at 11:23:50 UTC on the 20th of February 2025 (MJD = 60726.475), about 9.20 hr after the EP WXT trigger. We utilized the astroalign (Beroiz et al. 2020, A&C, 32, 100384) and astropy (Astropy Collaboration et al. 2022, ApJ, 935, 167) packages to align and stack the individual frames. We do not find any evidence of a new and uncataloged source in the stacked images within the 2.81 arcminute error circle of EP-WXT localization. Moreover, we employed the Python-based package AutoPhOT (Brennan & Fraser, 2022, A&A, 667, A62) to perform template subtraction using the "sfft" (Hu, 2022, ApJ, 936, 157) and "hotpants" (Becker A., 2015, ascl.soft. ascl:1504.004) algorithms using a template from Pan-STARRS1 (Chambers et al. 2016, arXiv:1612.05560). We found no evidence of any prominent candidate optical counterpart in the difference image as well. We further employed AutoPhOT to perform the PSF photometry. The details of the observations and measured 3-sigma upper limit (in the AB system) are as follows: Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | avg. Seeing | med. Airmass LOT | r | 60726.475 | 9.20 | 300 * 6 | > 22.65| 1".12 | 1.13 The non-detection of any optical counterpart in our observations is consistent with Xinglong observations, as reported by Zhang et al. (GCN 39393). The presented magnitudes are calibrated using the field stars from the Pan-STARRS1 catalog and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E(B-V) = 0.12 mag in the direction of the transient (Schlafly & Finkbeiner 2011). View this GCN Circular online at https://gcn.nasa.gov/circulars/39400. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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[vsnet-grb-info 37410] SVOM trigger sb25022102 is not an astrophysical event
by GCN Circulars 21 Feb '25

21 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39399 SUBJECT: SVOM trigger sb25022102 is not an astrophysical event DATE: 25/02/21 08:39:54 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> R.-Z. Li (YNAO, CAS), Y. Wang (PMO, CAS), J.-X. Cao, D.-F. Kong (GXU), W.-J. Xie, D.-H. Zhao (NAOC), M. Moita (CEA), L. Zhang (IHEP) report on behalf of the SVOM mission team. At 2025-02-21T02:57:58 SVOM issued an alert with the burst_id sb25022102, see also (Li et al, GCN 39398). This event is no longer … [View More]

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[vsnet-grb-info 37409] SVOM/sb25022102: SVOM detection of an X-ray transient
by GCN Circulars 21 Feb '25

21 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39398 SUBJECT: SVOM/sb25022102: SVOM detection of an X-ray transient DATE: 25/02/21 04:52:41 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> R.-Z. Li (YNAO, CAS), Y. Wang (PMO, CAS), J.-X. Cao, D.-F. Kong (GXU), W.-J. Xie, D.-H. Zhao (NAOC), M. Moita (CEA), L. Zhang (IHEP) report on behalf of the SVOM mission team: The SVOM/ECLAIRs telescope triggered and located a soft X-ray transient (SVOM burst-id sb25022102) starting at 2025-02-21T02:57:58.938 UTC (… [View More]

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[vsnet-grb-info 37408] GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
by GCN Circulars 21 Feb '25

21 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39397 SUBJECT: GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart DATE: 25/02/21 04:03:03 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Alan M. Watson (UNAM), Camila Angulo (UNAM), William H. Lee (UNAM), Enrique Moreno Méndez (UNAM), Stéphane Basa (UAR Pytheas), Dalya Akl (AUS), Sarah Antier (OCA), Jean-Luc Atteia (IRAP), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM),… [View More]

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[vsnet-grb-info 37407] GRB 250221A: Swift detection of a burst with an optical counterpart
by GCN Circulars 21 Feb '25

21 Feb '25

TITLE: GCN CIRCULAR NUMBER: 39396 SUBJECT: GRB 250221A: Swift detection of a burst with an optical counterpart DATE: 25/02/21 03:53:15 GMT FROM: David Palmer at LANL <palmer(a)lanl.gov> R. Caputo (GSFC), C. Gronwall (PSU), R. Gupta (NASA GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), T. M. Parsotan (GSFC) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 03:34:37 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB … [View More]250221A (trigger=1290305). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 59.477, -15.139 which is RA(J2000) = 03h 57m 54s Dec(J2000) = -15d 08' 18" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak structure with a duration of about 5 sec. The peak count rate was ~2200 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 03:36:39.9 UT, 122.9 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 59.46251, -15.13379 which is equivalent to: RA(J2000) = 03h 57m 51.00s Dec(J2000) = -15d 08' 01.6" with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 53 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. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (3.73 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.1 (+2.63/-2.31) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 250 seconds with the U filter starting 340 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 03:57:51.06 = 59.46274 DEC(J2000) = -15:07:59.2 = -15.13311 with a 90%-confidence error radius of about 0.76 arc sec. This position is 2.4 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.82 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.046. Burst Advocate for this burst is R. Caputo (regina.caputo AT nasa.gov). 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/39396. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L… [View Less]

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