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

[vsnet-grb-info 38326] IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 30 Apr '25

30 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40297 SUBJECT: IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/04/30 22:01:21 GMT FROM: Alicia Mand at IceCube/UW-Madison <aemand(a)wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-250429A (https://gcn.nasa.gov/circulars/40280) in a time range of 1000 seconds centered on the alert event time (2025-04-29 15:14:55.620 UTC to 2025-04-29 15:31:35.620 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-250429A.The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-250429A is 1.4e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 8e+04 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2025-04-28 15:23:15.620 UTC to 2025-04-30 15:23:15.620 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-250429A is 1.7e-01 GeV cm^-2 in a 2 day time window. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/40297. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38325] IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 30 Apr '25

30 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40296 SUBJECT: IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/04/30 21:59:47 GMT FROM: Alicia Mand at IceCube/UW-Madison <aemand(a)wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-250426A (https://gcn.nasa.gov/circulars/40253) in a time range of 1000 seconds centered on the alert event time (2025-04-26 17:36:38.160 UTC to 2025-04-26 17:53:18.160 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-250426A. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-250426A is 1.4e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 9e+04 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2025-04-25 17:44:58.160 UTC to 2025-04-27 17:44:58.160 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-250426A is 1.7e-01 GeV cm^-2 in a 2 day time window. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/40296. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38324] GRB 250430A: AKO Optical Afterglow Detection
by GCN Circulars 30 Apr '25

30 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40295 SUBJECT: GRB 250430A: AKO Optical Afterglow Detection DATE: 25/04/30 19:20:09 GMT FROM: Mohammad Odeh at Al Khatim Observatory M44 <mshodeh(a)gmail.com> Mohammad Odeh (Al-Khatim Observatory, AKO, operated by the International Astronomical Center in Abu Dhabi, UAE), and Nidhal Guessoum (American University of Sharjah, UAE), report: We observed the field of GRB 250430A detected by Swift/BAT (Parsotan et al., GCN 40292), using our 0.36m f/7.7 robotic telescope. The observation session began on 30 April 2025 at 17:52 UT, 21 minutes after the trigger. We obtained multiple 180-second exposures using the Ic filter. An uncatalogued object is faintly visible at the location below, which could be the optical afterglow: R.A. (J2000): 15:33:32.95 Dec. (J2000): -18:07:05.9 The following observation was calculated using the Atlas catalogue as a reference: ---------------------------------------------------------------------------- - ObsTime (mid), Exposure (sec), Filter, Mag ---------------------------------------------------------------------------- - 2025-04-30T18:29:42Z, 15 x 180s (stacked), Ic, 18.6 +/- 0.22 ---------------------------------------------------------------------------- - The magnitude is not corrected for galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40295. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38323] GRB 250430A: Kanata optical upper limit
by GCN Circulars 30 Apr '25

30 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40294 SUBJECT: GRB 250430A: Kanata optical upper limit DATE: 25/04/30 18:52:29 GMT FROM: Koji Kawabata at HASC,Hiroshima U <kawabtkj(a)hiroshima-u.ac.jp> K. S. Kawabata, T. Hori, T. Nakaoka (Hiroshima Univ.) report on behalf of Kanata team: We performed optical imaging polarimetry to the field of the GRB 180720B (Parsotan et al. GCN 40292; Lipunov et al. GCN 40291) from 2025-04-30 17:34:03 UT (162 seconds after the trigger) with HONIR attached to the 1.5-m Kanata telescope at Higashi-Hiroshima Observatory, Japan. We did not detect any new optical source up to a limiting magnitude of Rc = 16.0 (3-sigma; Vega mag) at the position of the UVOT source in our first 30 second exposure. View this GCN Circular online at https://gcn.nasa.gov/circulars/40294. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38322] EP 250427A: Optical counterpart detection by LCO.
by GCN Circulars 30 Apr '25

30 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40293 SUBJECT: EP 250427A: Optical counterpart detection by LCO. DATE: 25/04/30 18:45:08 GMT FROM: ankur ghosh at CAPP, University of Johannesburg <ghosh.ankur1994(a)gmail.com> Ankur Ghosh, Soebur Razzaque (CAPP, University of Johannesburg), Alexander Moskvitin, Yulia Sotnikova (SAO RAS), Naveen Dukiya (ARIES), Rahul Gupta (NASA GSFC) on behalf of a larger collaboration. We observed the field of the EP 250427A triggered by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission and Fermi (Wang et al. GCN 40257, Ravasio et al. GCN 40262) in the r filter of the 0.4 m SCICAM QHY600 at the Las Cumbres Observatory Global Telescope (LCOGT) node located at South African Astronomical Observatory (SAAO). The 0.4 m SCICAM QHY600 is equipped with 9576 x 6388 pixel CCD (FOV: 1.9 x 1.2 degrees, scale: 0.74 arcsec/pixel) but we only used the FOV of 30 x 30 arcmin for our observation. Observations began on April 27, 2025, starting 19.90 hours after the GRB trigger. We clearly detect the optical transient (OT) reported by GCNs (Perez-Garcia et al., GCN #40259), TRT (Liu et al., GCN #40260), COLIBRÍ (Becerra et al., GCN #40261), REM (Brivio et al., GCN #40264), LCO (Pérez-Fournon et al., GCN #40267), LT (Qiang Xi et al., GCN #40269), GIT (Swain et al., GCN #40270), COLIBRÍ (Magnani et al., GCN #40271), Lesedi (S. de Wet et al., GCN #40272), FTW (Busmann et al., GCN #40273), OHP/T193 (Amram et al., GCN #40275, Amram et al., GCN #40288, Eappachen et al., GCN #40289) in our r band image. ------------------------------------------------------------------------------------------------------ |Date| |JD start| |t-T0 (hours)| |Exp (sec)| |Filter| |Magnitude| ------------------------------------------------------------------------------------------------------ 2025-04-27 2460793.48177 19.91 2 x 600 r r = 19.05 +/- 0.07 ------------------------------------------------------------------------------------------------------ The field was calibrated against nearby APASS stars, with magnitudes converted using Lupton (2005) equations, and has not been corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40293. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38321] GRB 250430A: Swift detection of a burst with optical counterpart
by GCN Circulars 30 Apr '25

30 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40292 SUBJECT: GRB 250430A: Swift detection of a burst with optical counterpart DATE: 25/04/30 18:07:07 GMT FROM: Tyler Parsotan at NASA GSFC <tyler.parsotan(a)nasa.gov> T. M. Parsotan (GSFC), C. Gronwall (PSU), R. Gupta (NASA GSFC), N. J. Klingler (GSFC/UMBC/CRESSTII), M. J. Moss (GSFC), K. L. Page (U Leicester), M. H. Siegel (PSU) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 17:31:21 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250430A (trigger=1308754). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 233.428, -18.083 which is RA(J2000) = 15h 33m 43s Dec(J2000) = -18d 04' 59" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi peak structure with a duration of about 20 sec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 17:33:37.5 UT, 157.3 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 233.38611, -18.11784 which is equivalent to: RA(J2000) = 15h 33m 32.67s Dec(J2000) = -18d 07' 04.2" with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 190 arcseconds from the BAT onboard position, outside 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 (9.57 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.5 (+2.62/-2.27) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 161 seconds after the BAT trigger. There is a candidate afterglow in the list of sources generated on-board at RA(J2000) = 15:33:32.85 = 233.38688 DEC(J2000) = -18:07:06.2 = -18.11840 with a 90%-confidence error radius of about 1.10 arc sec. This position is 3.65 arc sec. from the center of the XRT error circle. The estimated magnitude is 19.44 with a 1-sigma error of about 0.35. No correction has been made for the expected extinction corresponding to E(B-V) of 0.092. Burst Advocate for this burst is T. M. Parsotan (tyler.parsotan 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/40292. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38320] Swift GRB250430.73: Global MASTER-Net observations report
by GCN Circulars 30 Apr '25

30 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40291 SUBJECT: Swift GRB250430.73: Global MASTER-Net observations report DATE: 25/04/30 18:03:45 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, 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.Sosnovskij (CrAO), 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB250430.73 (trigger No 1308754,15h 33m 42.72s , -18d 04m 58.8s, R=0.05) errorbox 1266 sec after notice time and 1293 sec after trigger time at 2025-04-30 17:52:33 UT, with upper limit up to 18.2 mag. The observations began at zenith distance = 77 deg. The sun altitude is -23.9 deg. The galactic latitude b = 29 deg., longitude l = 349 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2858290 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 1384 | MASTER-SAAO | C | 180 | 17.5 | 1583 | MASTER-SAAO | C | 180 | 18.2 | 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/40291. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38319] EP250428b: FTW optical and NIR observations
by GCN Circulars 30 Apr '25

30 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40290 SUBJECT: EP250428b: FTW optical and NIR observations DATE: 25/04/30 17:02:17 GMT FROM: Malte Busmann at Ludwig-Maximilians-Universität München <m.busmann(a)physik.lmu.de> Malte Busmann (LMU), Brendan O’Connor (Carnegie Mellon U.), Daniel Gruen (LMU), and Antonella Palmese (Carnegie Mellon U.) report: We observed the localization of EP250428b (Liu et al., GCN 40277) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i and J band simultaneously for 10 x 180 s starting at 2025-04-30T01:13:27 UT (1.86 days after the trigger). We performed difference imaging in the r and i band with templates from the DESI Legacy Surveys and do not detect any new sources in the improved EP/FXT localization (Wu et al., GCN 40285). The 3 sigma upper limits are r > 23.9 mag i > 23.5 mag. These upper limits are consistent with previous reports (Lipunov et al., GCN 40278; Konno et al., GCN 40281; Moskvitin et al., GCN 40282; Xin et al., GCN 40283; Salgundi et al., GCN 40284). The magnitudes are calibrated against the PS1 catalog and not corrected for Galactic extinction. We thank Christoph Ries from the Wendelstein Observatory staff for obtaining these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/40290. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38318] EP250427a/GRB250427A: HCT optical follow-up
by GCN Circulars 30 Apr '25

30 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40289 SUBJECT: EP250427a/GRB250427A: HCT optical follow-up DATE: 25/04/30 12:55:53 GMT FROM: anirudhsalgundi(a)gmail.com D. Eappachen (IIA), V. Swain (IITB), A. Salgundi (IITB), D.K. Sahu (IIA), A.P. Saikia (IITB), G. C. Anupama (IIA), V. Bhalerao (IITB), A. Balasubramanian (IIA), S. Barway (IIA), S. Bandari (IAO): We observed the field of EP250427a (Wang et al., GCN #40257), also detected by Fermi-GBM (Ravasio et al., GCN #40262) with the 2.0m Himalayan Chandra Telescope (HCT) of the Indian Astronomical Observatory (IAO). We obtained multiple exposures in the SDSS r' filter starting at 2025-04-29 22:10:49.88 UT (~2.77 days post trigger). We detected the source in our stacked image and obtained the following photometric result: | JD (mid) | Filter | Exposure (s) | Mag (AB) | Limiting Magnitude (AB) | | ----------------- | ------- | ------------------ | -------------- |--------------| | 2460795.433742 | r' | 5 x 240 | 21.70 +/- 0.12 | 21.9 | The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction. Our result is consistent with BOOTES-7 (Perez-Garcia et al., GCN #40259), TRT (Liu et al., GCN #40260), COLIBRÍ (Becerra et al., GCN #40261), REM (Brivio et al., GCN #40264), LCO (Pérez-Fournon et al., GCN #40267), LT (Qiang Xi et al., GCN #40269), GIT (Swain et al., GCN #40270), COLIBRÍ (Magnani et al., GCN #40271), Lesedi (S. de Wet et al., GCN #40272), FTW (Busmann et al., GCN #40273), OHP/T193 (Amram et al., GCN #40275). These observations were carried out under the ToO program HCT-2025-C1-P08. We thank the HCT staff for their support during the observations. The Indian Astronomical Observatory is operated by the Indian Institute of Astrophysics, Bengaluru, India. View this GCN Circular online at https://gcn.nasa.gov/circulars/40289. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38317] EP250427a / GRB 250427A: OHP/T193 continued photometric observations
by GCN Circulars 30 Apr '25

30 Apr '25

TITLE: GCN CIRCULAR NUMBER: 40288 SUBJECT: EP250427a / GRB 250427A: OHP/T193 continued photometric observations DATE: 25/04/30 12:54:46 GMT FROM: Christophe Adami at LAM <christophe.adami(a)lam.fr> P. Amram (LAM/AMU), S. Basa (Pytheas/OHP/LAM), C. Adami (LAM/Pytheas/AMU), N.A. Rakotondrainibe (LAM), S. Vergani (CNRS, Obs. de Paris, LUX), A. Saccardi (CEA/Irfu), J. T. Palmerio (CEA), B. Schneider (LAM), J. T. Palmerio (CEA/Irfu) report on behalf of the MISTRAL-GRB collaboration: We re-observed EP250427a / GRB 250427A (Wang et al. GCN 40257, Ravasio et al. GCN 40262) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager in blue setting. We obtained 3x900sec in the r’ band starting at 02:42:04UT on 2025-04-30 (T0+47.1 h after the trigger). The optical afterglow reported by Pérez-García et al. GCN 40259; Liu et al. GCN 40260; Becerra et al. GCN 40261; Brivio et al. GCN 40264; Chornock et al. GCN 40265; Saccardi et al. GCN 40266; Pérez-Fournon et al. GCN 40267; Xi et al. GCN 40269; Swain et al. GCN 40270; Magnani et al. GCN 40271; de Wet et al. GCN 40272; Busmann et al. GCN 40273, Wang et al. GCN40274, Amram et al. GCN 40275, Siegel et al. GCN 40279 is still detected at r = 21.50 +/- 0.18 mag (AB). The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitude is not corrected for Galactic extinction. We acknowledge the excellent support from the Observatoire de Haute-Provence and in particular J. Schmitt, J.C. Brunel, F. Huppert, F. Moreau, Stephane Favard, Jean Pierre Troncin, Jean Balcaen and Yoann Degot-Longhi. View this GCN Circular online at https://gcn.nasa.gov/circulars/40288. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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