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

[vsnet-grb-info 38840] GRB250620C: Fermi GBM Observation
by GCN Circulars 20 Jun '25

20 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40799 SUBJECT: GRB250620C: Fermi GBM Observation DATE: 25/06/20 23:48:00 GMT FROM: oindabimukherjee(a)gmail.com O. Mukherjee (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 16:07:09.92 UT on 20 June 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB250620C (trigger 772128434/250620672). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 142.61, Dec = 54.96 (J2000 degrees, equivalent to J2000 9h 30m, +54d 57'), with a statistical uncertainty of 1.00 degrees. (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a mixture of two Gaussians, one with a radius of 1.8 degrees (52% contribution) and one with a radius of 4.1 degrees (47% contribution) [A. Goldstein et al. 2020, ApJ, 895, 1]). The angle from the Fermi LAT boresight is 124 degrees. The GBM light curve consists of multiple emission episodes with a duration (T90) of about 32 s (50-300 keV). The time-averaged spectrum from T0 to T0+35.7 s is best fit by a Band function with Epeak= 371 +/- 15 keV, alpha = -0.93 +/- 0.02 and beta = -2.6 +/- 0.2. The event fluence (10-1000 keV) in this time interval is (6.64 +/- 0.07)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.96 s in the 10-1000 keV band is 50.1 +/- 0.7 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/40799. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38839] GRB 260506A - SVOM/ECLAIRs Refined analysis
by GCN Circulars 20 Jun '25

20 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40798 SUBJECT: GRB 260506A - SVOM/ECLAIRs Refined analysis DATE: 25/06/20 22:04:35 GMT FROM: sebastien.guillot(a)irap.omp.eu Authors: S. Guillot (IRAP), F. Cangemi, A. Coleiro (APC), M.-G. Bernardini (INAF-OAB, LUPM), O. Godet (IRAP), Chenwei WANG (IHEP), Lin LAN (NAOC) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 250506A (SVOM burst-id sb25050601). The burst that triggered ECLAIRs onboard (GCN 40358) consists of a single pulse with a duration of T90 = 6.4 +1.0/-0.6 s in the 4-120 keV energy band. We note that ECLAIRs only saw the first peak of this GRB since the source passed behind the Earth during the burst. Therefore, this T90 value is only for the first peak, and is shorter than those measured by Fermi/GBM (GCN 40362) and GECAM (GCN 40396). The time-averaged spectrum of the burst from T0 + 4.12 sec to T0 + 12.12 sec (T0 = 2025-05-06T02:23:16.88) in the energy range 5-115 keV is best fit by a broken power-law model with a break energy of 14.2 +3.8/-1.9 keV, a photon index of -0.3 +/- 0.2 before the break, and of -0.97 +0.06/-0.08 after the break. The photon index after the break is broadly consistent with the PL index (50-300 keV) reported from the Fermi/GBM analysis (GCN 40362). With this model, the total 4-120 keV fluence, assuming the T90 measured, is 1.75 +0.28/-0.5 x 10^-6 erg/cm^2. All the quoted errors are at the 90% confidence level. Other models (power law, cutoff power law, blackbody + power law, gamma-ray burst continuum) do not satisfactorily fit the data. The comparison of the power-law and broken power-law fits yields a spectral break significance of 5.1 sigma (Gaussian two-sided). We note that the calibration of SVOM/ECLAIRs is undergoing thus these results are preliminary. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic Universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Sébastien Guillot (IRAP) (sebastien.guillot at irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/40798. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38838] The EP-WXT trigger 01709179071 is likely a flaring star
by GCN Circulars 20 Jun '25

20 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40797 SUBJECT: The EP-WXT trigger 01709179071 is likely a flaring star DATE: 25/06/20 20:59:28 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> X. Mao, Y. J. Song, T. Zhao, Z. X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709179071 at the time of 2025-06-20T19:46:46, is likely a stellar flare associated with 2MASS J21370885-6036054. The estimated flux of the flare is around 1e-10 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 2.4e31 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/40797. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38837] GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
by GCN Circulars 20 Jun '25

20 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40796 SUBJECT: GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst DATE: 25/06/20 19:50:54 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Rachel Hamburg (USRA), Oindabi Mukherjee (USRA), Samuele Ronchini (PSU), Aaron Tohuvavohu (Caltech), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (PSU), Gayathri Raman (PSU) report: Swift/BAT did not localize GRB 250620A onboard (T0: 2025-06-20T08:05:18.94 UTC, Fermi/GBM trig 772099523) The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 7.3 in a 0.512 s analysis time bin, starting at T0 + 8.96 s. This corresponds to a FAR ~ 5e-4 Hz. This is ~9 s after the initial short spike detected by Fermi/GBM, but is temporally coincident with a separate pulse seen in the Fermi/GBM lightcurve. The initial short spike is also detected by NITRATES, but very weakly with a sqrt(TS) of 6.8 (FAR ~ 2e-3 Hz) in a 0.256 s analysis time bin, starting at T0 - 0.128 s. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 15,094 deg2 and the 50% credible area is 5,333 deg2. The integrated probability inside the coded field of view is 1%. The NITRATES skymap is very large but is consistent with the Fermi localization reported in the final position notice (GCN 40791). A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=772099554/#:~:te… The probability skymap file can be downloaded from the link here [skymap_fits_file](https://guano.swift.psu.edu/files/772099554/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/772099554/0_n_JOI… Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=772099554 GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/40796. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38836] GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
by GCN Circulars 20 Jun '25

20 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40795 SUBJECT: GRB 250619B: Swift/BAT-GUANO localization skymap of a burst DATE: 25/06/20 17:11:42 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Samuele Ronchini (PSU), Aaron Tohuvavohu (Caltech), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (PSU) report: Swift/BAT did not localize GRB 250619B onboard (T0: 2025-06-19T23:36:17.17 UTC, Fermi/GBM trig 772068982) The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 7.9 in a 8.192 s analysis time bin, starting at T0 - 2.048 s. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 10,760 deg2 and the 50% credible area is 1,197 deg2. The integrated probability inside the coded field of view is 30%. The NITRATES skymap is consistent with the Fermi localization reported in the final position notice (GCN 40788). The combined Fermi/GBM+NITRATES 90% credible area is 652 deg2 and the 50% credible area is 146 deg2. A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=772069012/#:~:te… The probability skymap and joint skymap files can be downloaded from the links here [skymap_fits_file](https://guano.swift.psu.edu/files/772069012/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/772069012/0_n_JOI… Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=772069012 GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/40795. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38835] GRB 250620C: Fermi GBM Final Real-time Localization
by GCN Circulars 20 Jun '25

20 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40794 SUBJECT: GRB 250620C: Fermi GBM Final Real-time Localization DATE: 25/06/20 16:18:37 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 16:07:09 UT on 20 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250620C (trigger 772128434.916854 / 250620672). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 142.6, Dec = 55.0 (J2000 degrees, equivalent to J2000 09h 30m, 55d 00'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 124.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250620672/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250620672/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250620672/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40794. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38834] Fermi trigger No 772128434: Global MASTER-Net observations report
by GCN Circulars 20 Jun '25

20 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40793 SUBJECT: Fermi trigger No 772128434: Global MASTER-Net observations report DATE: 25/06/20 16:16:06 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-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB250620.67 (trigger No 772128434,09h 30m 26.40s , +54d 57m 36.0s, R=1) errorbox 96 sec after notice time and 133 sec after trigger time at 2025-06-20 16:09:23 UT, with upper limit up to 15.7 mag. Observations started at twilight. The observations began at zenith distance = 58 deg. The sun altitude is -14.4 deg. The galactic latitude b = 45 deg., longitude l = 161 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2910184 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 148 | 2025-06-20 16:09:23 | MASTER-Tunka | (09h 40m 06.83s , +56d 13m 43.0s) | P- | 30 | 14.9 | 148 | 2025-06-20 16:09:23 | MASTER- | (09h 21m 21.53s , +56d 18m 40.7s) | C | 30 | 14.5 | 250 | 2025-06-20 16:10:55 | MASTER-Tunka | (09h 40m 05.78s , +56d 08m 46.7s) | P- | 50 | 15.7 | 250 | 2025-06-20 16:10:55 | MASTER- | (09h 21m 23.28s , +56d 13m 19.9s) | C | 50 | 15.3 | 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/40793. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38833] GRB 250620B: Fermi GBM Final Real-time Localization
by GCN Circulars 20 Jun '25

20 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40792 SUBJECT: GRB 250620B: Fermi GBM Final Real-time Localization DATE: 25/06/20 13:33:28 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 13:22:56 UT on 20 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250620B (trigger 772118581.936592 / 250620558). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 67.1, Dec = -30.2 (J2000 degrees, equivalent to J2000 04h 28m, -30d 11'), with a statistical uncertainty of 6.0 degrees. The angle from the Fermi LAT boresight is 90.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250620558/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250620558/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250620558/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40792. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38832] GRB 250620A: Fermi GBM Final Real-time Localization
by GCN Circulars 20 Jun '25

20 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40791 SUBJECT: GRB 250620A: Fermi GBM Final Real-time Localization DATE: 25/06/20 08:15:50 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 SHORT GRB At 08:05:18 UT on 20 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250620A (trigger 772099523.9444 / 250620337). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 46.2, Dec = 65.8 (J2000 degrees, equivalent to J2000 03h 04m, 65d 47'), with a statistical uncertainty of 6.2 degrees. The angle from the Fermi LAT boresight is 164.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250620337/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250620337/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250620337/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40791. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38831] EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
by GCN Circulars 20 Jun '25

20 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40790 SUBJECT: EP-WXT trigger 01709179036: a new outburst of GRS 1739-278 DATE: 25/06/20 05:30:21 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> H. Sun (NAO, CAS), J. Yang (NJU), H. Z. Wu (HUST), X. L. Chen (YNU), W. D. Zhang (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of a new X-ray outburst from the black hole low-mass X-ray binary GRS 1739-278, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The source exhibited a rapid rise in its 0.5-4 keV flux since June 15th, 2025 and triggered EP-WXT (ID: 01709179036) at 2025-06-19T14:54:11 (UTC, ATel #17238). A follow-up observation with the Follow-up X-ray Telescope (FXT) on board EP was performed automatically around 2 minutes after the trigger, with an exposure time of 1.2 ks. A bright X-ray source, whose position is consistent with GRS 1739-278, was detected by FXT, thus confirming the new outburst of GRS 1739-278. The FXT spectrum can be fitted by an absorbed power-law with a photon index of 2.1 (+/-0.1) and a neutral hydrogen column density of 2.3 (+/-0.1) x 10^22 cm^-2. The derived unabsorbed flux in 0.5-10 keV is 1.8 (+/-0.1) x 10^-9 erg/s/cm^2. Multi-wavelength follow-up observations are strongly encouraged. 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/40790. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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