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

[vsnet-grb-info 38670] GRB 250605A: LT optical observations
by GCN Circulars 05 Jun '25

05 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40634 SUBJECT: GRB 250605A: LT optical observations DATE: 25/06/05 22:51:33 GMT FROM: Ben Gompertz at U of Birmingham <b.gompertz(a)bham.ac.uk> B. P. Gompertz (U. Birmingham), Dimple (U. Birmingham), A. Martin-Carrillo (UCD), G. Corcoran (UCD) and D. B. Malesani (DAWN/NBI and Radboud), report on behalf of a larger collaboration: We initiated follow-up observations of GRB 250605A (Gupta et al., GCN 40633) with the IO:O camera on the 2m robotic Liverpool Telescope (LT). Observations began at 20:48:52.89 UT, ~2 hours after the Swift/BAT trigger, and consisted of 10x60 s exposures in the SDSS i filter. Observations were taken close to twilight, at high airmass, and the target was 28 deg from the moon at 77% illumination. Within the Swift/XRT error box, we detect a possible optical counterpart, not present in archival imaging, with an AB magnitude of i ~ 21.1 at RA = 11:07:49.7, Dec = -19:47:15.4. However, this detection is only significant at the 2-sigma level and further, deeper observations are required to confirm its reality. Formally, we measure a 3-sigma upper limit of i > 20.6 within the XRT localisation region. We also note the presence of a faint source visible in the Legacy Survey archival imaging with an AB magnitude of i = 23.54. The source position is consistent with the possible optical counterpart, and may be the host galaxy of GRB 250605A. Magnitudes are calibrated against nearby Pan-STARRS stars and not corrected for galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40634. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38669] GRB 250605A: Swift detection of a burst
by GCN Circulars 05 Jun '25

05 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40633 SUBJECT: GRB 250605A: Swift detection of a burst DATE: 25/06/05 19:08:03 GMT FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk> R. Gupta (NASA GSFC), J. J. DeLaunay (PSU), S. Dichiara (PSU), C. Gronwall (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII), H. A. Krimm (NSF), M. J. Moss (GSFC), K. L. Page (U Leicester), T. M. Parsotan (GSFC), M. H. Siegel (PSU) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 18:52:31.27 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250605A (trigger=1321323). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 166.977, -19.795 which is RA(J2000) = 11h 07m 54s Dec(J2000) = -19d 47' 42" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a complex light curve with one strong pulse between T0-2 sec to T0+10 sec and a second dimmer but broad pulse between T0+40 sec to T0+100 sec. The peak count rate was 4,000 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 18:54:09.2 UT, 98.0 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 166.9571, -19.7882 which is equivalent to: RA(J2000) = 11h 07m 49.70s Dec(J2000) = -19d 47' 17.5" with an uncertainty of 5.5 arcseconds (radius, 90% containment). This location is 71 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. UVOT took a finding chart exposure of 144 seconds with the White filter starting 106 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.039. 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/40633. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38668] Swift GRB250605.79: Global MASTER-Net observations report
by GCN Circulars 05 Jun '25

05 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40632 SUBJECT: Swift GRB250605.79: Global MASTER-Net observations report DATE: 25/06/05 18:56:40 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 GRB250605.79 (trigger No 1321323,11h 07m 54.48s , -19d 47m 42.0s, R=0.05) errorbox 16 sec after notice time and 37 sec after trigger time at 2025-06-05 18:53:08 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 31 deg. The sun altitude is -39.9 deg. The galactic latitude b = 37 deg., longitude l = 273 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2893644 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 43 | MASTER-SAAO | C | 10 | 17.9 | 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/40632. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38667] Konus-Wind detection of GRB 250601A
by GCN Circulars 05 Jun '25

05 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40631 SUBJECT: Konus-Wind detection of GRB 250601A DATE: 25/06/05 15:52:19 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The short-duration GRB 250601A (Fermi GBM detection: Fermi GBM team, GCN 40596; Sharma et al., GCN 40621; Swift/BAT-GUANO localization: DeLaunay et al., GCN 40600) triggered Konus-Wind at T0=62975.326 s UT (17:29:35.326). The burst light curve shows a multi-peaked pulse, which starts at ~T0-0.5 s and has a total duration of ~0.8 s. The emission is seen up to ~10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250601_T62975/ As observed by Konus-Wind, the burst had a fluence of 2.02(-0.28,+0.31)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0-0.004 s, of 7.00(-2.01,+2.06)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). Since the brightest peak of the burst light curve was detected before the trigger, the spectral analysis was performed using the KW 3-channel light curve data. Modelling the KW 3-channel time-integrated spectrum (measured from T0-0.492 s to T0+0.276 s) by a power law with exponential cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), yields alpha = 0.31(-0.37,+0.52) and Ep = 436(-62,+76) keV. All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/40631. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38666] IPN triangulation of GRB 250404B
by GCN Circulars 05 Jun '25

05 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40630 SUBJECT: IPN triangulation of GRB 250404B DATE: 25/06/05 15:32:58 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team, D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, E. Burns on behalf of the IPN, S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, A. Tohuvavohu, and J. DeLaunay on behalf of the Swift-BAT team, G. Waratkar, J.Joshi, V. Bhalerao, D. Bhattacharya, and S. Vadawale, on behalf of the Astrosat-CZTI team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report: The short-duration GRB 250404B (AstroSat CZTI detection: Salunke et al., GCN Circ. 40078) was detected by Konus-Wind, Swift (BAT), AstroSat (CZTI), and Mars-Odyssey (HEND) at about 66970 s UT (18:36:10). The burst was outside the coded field of view of the BAT. We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 273.629 (18h 14m 31s) -2.251 ( -2d 15' 03") Corners: 273.108 (18h 12m 26s) -2.676 ( -2d 40' 35") 274.127 (18h 16m 31s) -1.659 ( -1d 39' 32") 274.151 (18h 16m 36s) -1.842 ( -1d 50' 30") 273.131 (18h 12m 31s) -2.866 ( -2d 51' 58") --------------------------------------------- The error box area is 768 sq. arcmin, and its maximum dimension is 1.6 deg (the minimum one is 9 arcmin). The Sun distance was 100 deg. This localization may be improved. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB250404_T66970/IPN/ The HEALPix triangulation map is the multi-order HEALPix in units of probability density. The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. View this GCN Circular online at https://gcn.nasa.gov/circulars/40630. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38665] IPN triangulation of GRB 250529A
by GCN Circulars 05 Jun '25

05 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40629 SUBJECT: IPN triangulation of GRB 250529A DATE: 25/06/05 15:23:42 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team, D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, A. Goldstein, M. S. Briggs, C. Wilson-Hodge, and E. Burns on behalf of the Fermi GBM team, S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, A. Tohuvavohu, and J. DeLaunay on behalf of the Swift-BAT team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report: The long-duration GRB 250529A (Fermi-GBM detection: Fermi GBM team, GCN 40567) was detected by Fermi (GBM), Konus-Wind, Swift (BAT), and Mars-Odyssey (HEND) at about 13576 s UT (03:46:16). The burst was outside the coded field of view of the BAT. We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 18.193 (01h 12m 46s) +58.274 (+58d 16' 25") Corners: 21.244 (01h 24m 58s) +56.039 (+56d 02' 19") 14.840 (00h 59m 22s) +60.456 (+60d 27' 22") 14.829 (00h 59m 19s) +60.366 (+60d 21' 57") 21.225 (01h 24m 54s) +55.944 (+55d 56' 37") --------------------------------------------- The error box area is 1252 sq. arcmin, and its maximum dimension is 5.6 deg (the minimum one is 4 arcmin). The Sun distance was 48 deg. This localization may be improved. The IPN localization is consistent with, but reduces the area of, the Fermi-GBM (GCN 40567) localization. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB250529_T13600/IPN/ The HEALPix triangulation map is the multi-order HEALPix in units of probability density. The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. View this GCN Circular online at https://gcn.nasa.gov/circulars/40629. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38664] The EP-WXT trigger 01709177837 is likely a flaring star
by GCN Circulars 05 Jun '25

05 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40628 SUBJECT: The EP-WXT trigger 01709177837 is likely a flaring star DATE: 25/06/05 09:41:18 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> S. Q. Jiang (NAOC), T. C. Zheng (PMO), X. Y. Zhou (PRIC), H. W. Pan (NAOC) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709177837 at the time of 2025-06-05T09:24:19, is likely a stellar flare associated with RV Crt. The estimated flux of the flare is around 8e-11 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 4e32 erg/s. 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/40628. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38663] Fermi Gamma-ray Burst Monitor trigger 770470765/250601486 is not a GRB
by GCN Circulars 04 Jun '25

04 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40627 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 770470765/250601486 is not a GRB DATE: 25/06/04 15:35:09 GMT FROM: Joe Mangan at IJCLab <joseph.mangan(a)ijclab.in2p3.fr> J. Mangan (IJCLab/CNRS) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 770470765/250601486 at 11:39:20.34 UT on 01 June 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/40627. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38662] GRB 250601A: PRIME H band upper limit.
by GCN Circulars 04 Jun '25

04 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40626 SUBJECT: GRB 250601A: PRIME H band upper limit. DATE: 25/06/04 15:02:32 GMT FROM: N. Passaleva at Sapienza University of Rome <niccolo.passaleva(a)uniroma1.it> N. Passaleva (U Rome), O. Guiffreda (UMD), J. Durbak (UMD), M. Elkabir (U Rome), E. Troja (U Rome), A. S. Kutyrev (NASA/GSFC), S. B. Cenko (NASA/GSFC) Following the Fermi Gamma-ray Burst Monitor (GBM) detection (GCN 40596), and the Swift/BAT-GUANO arcminutes localization of same event, we observed the transient field in H filter with PRIME ~47.5 hours after the initial Fermi detection. Using Two Micron All Sky Survey (2MASS) for preliminary calibration we do not detect any uncatalogued source down to H>20.6 AB (3-sigma) not corrected for galactic extinction at the position of the candidates reported by Swift/XRT (Page et al. GCN 40604, Salvaggio et al., GCN 40606) and EP/FXT (Liu et al., GCN 40607). PRIME is a 1.8m telescope with 1.56 square degree FOV (0.5 arcsec/pixel) located in Sutherland, South Africa at the South African Astronomical Observatory (SAAO) (Kutyrev et al. 2023, Yama et al. 2023, Durbak et al. 2024). We thank the Osaka University observers at PRIME and the staff at SAAO for their support with these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/40626. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38661] GRB 250530A: SVOM/GRM analysis
by GCN Circulars 04 Jun '25

04 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40625 SUBJECT: GRB 250530A: SVOM/GRM analysis DATE: 25/06/04 03:52:55 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Chao Zheng, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: M. G. Bernardini (INAF-OAB, LUPM) Report on behalf of the SVOM team: SVOM/GRM detected the burst GRB 250530A at 2025-05-30T06:31:54.99 UTC (T0), which is also detected by SVOM/ECLAIRs (Wang et al., GCN #40576). With the event-by-event data downloaded through the X-band ground station, we conducted the standard analysis pipeline of GRB 250530A. The GRM light curve shows that this burst consists of a single pulse with a T90 of 15.0 +3.0/-4.0 s in the 15-5000 keV band, which is consistent with the result from VHF data. With the localization of ECLAIRs (RA=186.71, DEC=-2.5648), the time-averaged spectrum from T0 to T0+15 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.26 +0.18/-0.13 and the cutoff energy, parameterized as Epeak, is 707 +1140/-360 keV. The event fluence (10-1000 keV) in this time interval is (2.8 +/-0.4)E-06 erg/cm^2. Thus GRB 250530A is consistent with Type I GRBs in the 'Amati' relation diagram although the duration is much longer than 2 seconds, as shown at: https://www.bursthub.cn//admin/static/grb250530A_amati.png Further follow-up observations are encouraged. We note that the calibration of SVOM/GRM is undergoing thus these results are preliminary. Refined analysis will be reported later. 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/40625. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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