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

[vsnet-grb-info 37818] Fermi GRB 250321A: Global MASTER-Net observations report
by GCN Circulars 21 Mar '25

21 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39801 SUBJECT: Fermi GRB 250321A: Global MASTER-Net observations report DATE: 25/03/21 08:31:06 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 250321A ( Fermi GBM team, GCN 39793) errorbox 25226 sec after notice time and 25261 sec after trigger time at 2025-03-21 07:43:40 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 82 deg. The sun altitude is -37.1 deg. The galactic latitude b = -6 deg., longitude l = 56 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2818762 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 25341 | 2025-03-21 07:43:40 | MASTER-OAFA | (19h 30m 40.40s , +20d 25m 41.2s) | C | 160 | 16.0 | 25537 | 2025-03-21 07:46:56 | MASTER-OAFA | (19h 30m 47.85s , +20d 25m 03.0s) | C | 160 | 16.4 | 25733 | 2025-03-21 07:50:11 | MASTER-OAFA | (19h 30m 42.54s , +20d 24m 22.3s) | C | 160 | 16.7 | 26355 | 2025-03-21 08:00:33 | MASTER-OAFA | (19h 30m 43.53s , +20d 26m 11.7s) | C | 160 | 16.4 | 27421 | 2025-03-21 08:19:20 | MASTER-OAFA | (19h 30m 53.70s , +20d 27m 42.1s) | C | 40 | 17.0 | 27431 | 2025-03-21 08:19:20 | MASTER-OAFA | (19h 40m 32.05s , +20d 50m 27.7s) | C | 60 | 16.6 | 27559 | 2025-03-21 08:20:37 | MASTER-OAFA | (19h 30m 47.78s , +20d 27m 00.4s) | C | 160 | 16.8 | 27569 | 2025-03-21 08:20:38 | MASTER-OAFA | (19h 41m 30.19s , +20d 47m 56.2s) | C | 180 | 16.7 | 27694 | 2025-03-21 08:23:53 | MASTER-OAFA | (19h 30m 54.58s , +20d 27m 29.9s) | C | 40 | 17.1 | 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/39801. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37817] EP250321a: Einstein Probe detection of an X-ray transient
by GCN Circulars 21 Mar '25

21 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39800 SUBJECT: EP250321a: Einstein Probe detection of an X-ray transient DATE: 25/03/21 08:04:38 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> D. F. Hu (PMO, CAS), H. Q. Cheng (NAO, CAS), Z. H. Yang, Q. C. ZHAO (IHEP, CAS), L. Chen, W. D. Zhang (NAO, CAS) report on behalf of the Einstein Probe team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP250321a. The transient triggered EP-WXT (ID: 01709133009) at 2025-03-21 06:09:59 (UTC). The WXT position of the source is R.A. = 179.262 deg, DEC = 17.386 deg (J2000) with an uncertainty of 3.1 arcmin in radius (90% C.L. statistical and systematic). A follow-up observation with the Follow-up X-ray Telescope (FXT) has been scheduled. Further information will be updated when the telemetry data is received. 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). View this GCN Circular online at https://gcn.nasa.gov/circulars/39800. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37816] GRB 250321A: GOTO optical upper limits
by GCN Circulars 21 Mar '25

21 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39799 SUBJECT: GRB 250321A: GOTO optical upper limits DATE: 25/03/21 07:42:24 GMT FROM: Amit Kumar at Royal Holloway - UoL/ U of Warwick, UK <amitkundu515(a)gmail.com> A. Kumar, S. Belkin, B. P. Gompertz, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, F. Jimenez-Ibarra, D. O'Neill, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, G. Ramsay, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, E. Palle and D. Pollacco report on behalf of the GOTO collaboration: The Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) observed the field of GRB 250321A, detected by Fermi/GBM (Fermi GBM Team, GCN 39793) and Swift/BAT (Gupta et al., GCN 39794). The position of the Swift/XRT counterpart (Page, GCN 39798) was covered by GOTO-North at 05:25:29 UT on 2025-03-21 (4.7 hours post-trigger). The observations consisted of 4x90s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using recent survey observations of the same pointings. No optical counterpart is detected in the Swift/XRT localisation region (Page, GCN 39798) down to a 3-sigma L-band limit of 19.6 mag (AB). 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/39799. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37815] GRB 250321A: Swift-XRT localisation
by GCN Circulars 21 Mar '25

21 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39798 SUBJECT: GRB 250321A: Swift-XRT localisation DATE: 25/03/21 07:13:12 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team: Using 1.7 ks of XRT Photon Counting mode data starting 134 s after the BAT trigger on GRB 250321A (GCN Circ. 39794), an X-ray source was identified at a position of RA, Dec = 295.09873, 21.04146, which is equivalent to RA (J2000): 19h 40m 23.7s Dec (J2000): 21d 02′ 29.3″ with an uncertainty of 4.2 arcsec. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39798. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37814] GRB 250314A: Keck/NIRC2 J-band upper limit
by GCN Circulars 21 Mar '25

21 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39797 SUBJECT: GRB 250314A: Keck/NIRC2 J-band upper limit DATE: 25/03/21 06:55:25 GMT FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu> WeiKang Zheng, Alexei V. Filippenko (UC Berkeley), Chris Fassnacht, Prayaag Katta (UC Davis), D. B. Malesani (DAWN/NBI) and Jing Wang (NAOC), report on behalf of the KAIT GRB team: We observed the field of the SVOM GRB 250314A (Wang et al., GCN 39719) with the NIRC2 camera on the Keck II 10 m telescope. The observations were performed in the J band (without AO) starting on 2025 March 16 at 12:54:21 UTC (i.e., 2.0 days after the burst), and consisted of 2x120 s exposures. At the reported NIR afterglow position (Malesani et al., GCN 39727; Malesani et al., GCN 39732), we do not detect any counterpart with an upper limit of J > 19.4 mag (Vega). View this GCN Circular online at https://gcn.nasa.gov/circulars/39797. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37813] EP250226a/GRB 250226A: KAIT optical observations
by GCN Circulars 21 Mar '25

21 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39796 SUBJECT: EP250226a/GRB 250226A: KAIT optical observations DATE: 25/03/21 06:54:07 GMT FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu> WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, observed the field of EP250226a/GRB 250226A (Fermi GBM team, GCN 39479; Jiang et al., GCN 39482; Jiang et al., GCN 39513; Zhang et al., GCN 39492; Thakur et al., GCN 39518; Pathak et al., GCN 39530; Svinkin et al., GCN 39542; Ronchini et al., GCN 39672) on Feb 26 at 09:27:20 (~2.88 hours after GBM trigger) and lasted for 4 hours. A set of 160x60s images were obtained in the clear (roughly R) filters. We detect the optical afterglow (An et. al, GCN 39486; Zhu et. al, GCN 39487; Magnani et. al, GCN 39488; Li et. al, GCN 39489; Aryan et. al, GCN 39509; Zou et al., GCN 39511; Li et. al, GCN 39514; Jiang et al., GCN 39515; Poidevin et al., GCN 39524; Tanasan et al., GCN 39554) in our single images. We measure the OT brightness to be 19.6 +/- 0.1 mag (Vega) at 2.88 hours after GBM trigger. We observed the OT again on the following night with 60x60s exposures and detected the OT in the coadd image with 22.2 +/- 0.2 mag (Vega) at a mid time of 1.17 days. This gives a decay index of -1.04 between the two nights. View this GCN Circular online at https://gcn.nasa.gov/circulars/39796. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37812] GRB 250321A: Fermi GBM Observation
by GCN Circulars 21 Mar '25

21 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39795 SUBJECT: GRB 250321A: Fermi GBM Observation DATE: 25/03/21 06:04:23 GMT FROM: A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca(a)unitn.it> R. Hamburg (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 00:42:39.02 UT on 21 March 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250321A (trigger 764210564/250321030), which was also detected by Swift BAT (Gupta et al. 2025, GCN 39794). The Fermi GBM on-ground location is consistent with the Swift BAT position. The angle from the Fermi LAT boresight is 39 degrees. The GBM light curve shows one main pulse with a duration (T90) of about 6 s (50-300 keV). The time-averaged spectrum from T0-0.5 to T0+7.2 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.83 +/- 0.20 and the cutoff energy, parameterized as Epeak, is 101 +/- 12 keV. The event fluence (10-1000 keV) in this time interval is (1.04 +/- 0.08)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.13 s in the 10-1000 keV band is 4.7 +/- 0.3 ph/s/cm^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/" View this GCN Circular online at https://gcn.nasa.gov/circulars/39795. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37811] GRB 250321A: Swift detection of a burst
by GCN Circulars 21 Mar '25

21 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39794 SUBJECT: GRB 250321A: Swift detection of a burst DATE: 25/03/21 01:04:22 GMT FROM: David Palmer at LANL <palmer(a)lanl.gov> R. Gupta (NASA GSFC), J. A. Kennea (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 00:42:38 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250321A (trigger=1297508). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 295.077, +21.041 which is RA(J2000) = 19h 40m 19s Dec(J2000) = +21d 02' 27" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). Only the first 8 seconds of the BAT light curve after the trigger is available due to a telemetry gap. This data shows a complex structure with a duration of at least 10 sec. The peak count rate was ~2500 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 00:44:43.60 UT, 125.6 seconds after the BAT trigger. No source was detected in the 2.5-s promptly available image. We are waiting for the full dataset to detect and localise the XRT counterpart. Due to a telemetry gap, UVOT data are not available at this time. Although XRT did not report an X-ray counterpart in the limited immediately transmitted data, the significance of the BAT image (>10 sigma), the shape of the BAT light curve, and the simultaneous detection by Fermi/GBM (trigger 764210564) give us confidence that this is an astrophysical Gamma Ray Burst. Burst Advocate for this burst is R. Gupta (rahulbhu.c157 AT gmail.com). 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/39794. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37810] GRB 250321A: Fermi GBM Final Real-time Localization
by GCN Circulars 21 Mar '25

21 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39793 SUBJECT: GRB 250321A: Fermi GBM Final Real-time Localization DATE: 25/03/21 00:53:07 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 00:42:39 UT on 21 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250321A (trigger 764210564.016716 / 250321030). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 299.0, Dec = 17.1 (J2000 degrees, equivalent to J2000 19h 56m, 17d 06'), with a statistical uncertainty of 6.3 degrees. The angle from the Fermi LAT boresight is 44.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250321030/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250321030/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250321030/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39793. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37809] GRB 250320B: Fermi GBM Final Real-time Localization
by GCN Circulars 20 Mar '25

20 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39792 SUBJECT: GRB 250320B: Fermi GBM Final Real-time Localization DATE: 25/03/20 23:25:50 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 23:15:22 UT on 20 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250320B (trigger 764205327.02257 / 250320969). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 249.2, Dec = -21.8 (J2000 degrees, equivalent to J2000 16h 36m, -21d 48'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 31.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250320969/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250320969/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250320969/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39792. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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