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

[vsnet-grb-info 37017] LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
by GCN Circulars 22 Jan '25

22 Jan '25

TITLE: GCN CIRCULAR NUMBER: 39009 SUBJECT: LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources DATE: 25/01/22 07:51:46 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> K.L. Page (U. Leicester), P.A. Evans (U. Leicester), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), S.B. Cenko (NASA/GSFC), R.A.J. Eyles-Ferris (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), A.A. Breeveld (UCL-MSSL), S. Campana (INAF-OAB), J.J. Delaunay (PSU), M. De Pasquale (University of Messina), S. Dichiara (PSU), P. D’Avanzo (INAF-OAB), A. D’Aì (INAF-IASFPA) , V. D’Elia (ASI-SSDC & INAF-OAR), C. Gronwall (PSU), D. Hartmann (Clemson University), N. Klingler (NASA-GSFC / UMBC / CRESST II), N.P.M. Kuin (UCL-MSSL), S. Laha (NASA/GSFC), S.R. Oates (U. Birmingham), J.P. Osborne (U. Leicester), P. O’Brien (U. Leicester), M.J. Page (UCL-MSSL), G. Raman (PSU) S. Ronchini (PSU), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (U Tor Vergata, INAF) report on behalf of the Swift team: Swift has carried out 189 observations of the LVC error region for the GW trigger S250119cv convolved with the 2MPZ catalogue (Bilicki et al. 2014, ApJS, 210, 9), using the 'BAYESTAR' (version BAYESTAR.fits.gz) GW localisation map. As this is a 3D skymap, galaxy distances were taken into account in selecting which ones to observe. The observations currently span from 2.6 ks to 101 ks after the LVC trigger, and the XRT has covered 13.1 deg^2 on the sky (corrected for overlaps). This covers 68% of the probability in the 'ligo-skymap-from-samples' (version ligo-skymap-from-samples.fits.gz) skymap, and 69% after convolving with the 2MPZ galaxy catalogue, as described by Evans et al. (2016, MNRAS, 462, 1591). We have detected 5 X-ray sources. Each source is assigned a rank of 1-4 which describes how likely it is to be related to the GW trigger, with 1 being the most likely and 4 being the least likely. The ranks are described at https://www.swift.ac.uk/ranks.php. We have found: * 0 sources of rank 1 * 0 sources of rank 2 * 1 source of rank 3 * 4 sources of rank 4 RANK 3 sources ============== These are uncatalogued X-ray sources, however they are not brighter than previous upper limits, so do not stand out as likely counterparts to the GW trigger. | Source ID | RA | Dec | Err90 | | S250119cv_X6 | 03h 47m 22.56s | -74d 14' 45.7" | 8.9" | RANK 4 sources ============== These are catalogued X-ray sources, showing no signs of outburst compared to previous observations, so they are not likely to be related to the GW trigger. | Source ID | RA | Dec | Err90 | | S250119cv_X1 | 00h 56m 18.41s | +27d 53' 48.0" | 7.4" | | S250119cv_X4 | 00h 55m 50.96s | +26d 24' 41.2" | 12.8" | | S250119cv_X5 | 00h 58m 11.65s | +27d 34' 36.6" | 6.7" | | S250119cv_X11 | 00h 58m 29.90s | +26d 39' 11.5" | 8.7" | For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2, and photon index (Gamma)=1.7, unless otherwise stated. The results of the XRT automated analysis, including details of the sources listed above, are online at https://www.swift.ac.uk/LVC/S250119cv This circular is an official product of the Swift XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/39009. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37016] GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
by GCN Circulars 22 Jan '25

22 Jan '25

TITLE: GCN CIRCULAR NUMBER: 39008 SUBJECT: GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst DATE: 25/01/22 02:44:45 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 250119C onboard (T0: 2025-11-19T22:41:06.30 UTC, Fermi GCN 38990) 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 12.6 in a 0.256 s analysis time bin, starting at T0 - 0.064 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 12,500 deg2 and the 50% credible area is 4,093 deg2. The integrated probability inside the coded field of view is 3%. The NITRATES skymap is consistent with the Fermi localization. A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=759019301/#:~:te… The probability skymap file can be downloaded from the link here [skymap_fits_file](https://guano.swift.psu.edu/files/759019301/0_n_PROBMAP) 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=759019301 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/39008. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37015] GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
by GCN Circulars 22 Jan '25

22 Jan '25

TITLE: GCN CIRCULAR NUMBER: 39007 SUBJECT: GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst DATE: 25/01/22 02:44:43 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 250119B onboard (T0: 2025-01-19T08:27:02.72 UTC, Fermi GCN 38979, BALROG GCN 38980, INTEGRAL GCN 38997) 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 32.6 in a 8.192 s analysis time bin, starting at T0+16.3844 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 82 deg2 and the 50% credible area is 25 deg2. The integrated probability inside the coded field of view is 1%. The NITRATES skymap is consistent with the Fermi and BALROG localizations. A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=758968057/#:~:te… The probability skymap file can be downloaded from the link here [skymap_fits_file](https://guano.swift.psu.edu/files/758968057/0_n_PROBMAP) 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=758968057 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/39007. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37014] GRB 250121A: Fermi GBM Final Real-time Localization
by GCN Circulars 21 Jan '25

21 Jan '25

TITLE: GCN CIRCULAR NUMBER: 39006 SUBJECT: GRB 250121A: Fermi GBM Final Real-time Localization DATE: 25/01/21 23:46:35 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 23:36:05 UT on 21 Jan 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250121A (trigger 759195370.779232 / 250121983). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 225.1, Dec = -36.9 (J2000 degrees, equivalent to J2000 15h 00m, -36d 53'), with a statistical uncertainty of 1.1 degrees. The angle from the Fermi LAT boresight is 16.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250121983/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250121983/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250121983/… View this GCN Circular online at https://gcn.nasa.gov/circulars/39006. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37013] Fermi-LAT Gamma-ray Observations of IceCube-241224A
by GCN Circulars 21 Jan '25

21 Jan '25

TITLE: GCN CIRCULAR NUMBER: 39005 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-241224A DATE: 25/01/21 15:35:18 GMT FROM: Leo Pfeiffer at University of Würzburg <pfeiffer.leo(a)gmail.com> L. Pfeiffer (Univ. of Wuerzburg), S. Buson (DESY, Univ. of Wuerzburg), C. Bartolini (INFN Bari), S. Garrappa (Weizmann Institute of Science) and J. Sinapius (DESY) and P. M. Veres (Ruhr University Bochum) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the high-energy IC241224A neutrino event (GCN 38664) with all-sky survey data from the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. The IceCube event was detected on 2024-12-24 07:10:04.35 UTC (T0) with J2000 position RA = 184.97 (+0.59, -0.52) deg, Decl. = 2.76 (+0.67, -0.67) deg 90% PSF containment (J2000). No cataloged gamma-ray sources are found within the 90% IC241224A localization error (The Fourth Fermi-LAT catalog Data Release 4, The Fermi-LAT collaboration 2023, arXiv:2307.12546). We searched for the existence of intermediate (days to years) timescale emission from a new gamma-ray transient source. Preliminary analysis indicates no significant (>5sigma) new excess emission (> 100 MeV) within the IC241224A 90% confidence localization. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC241224A best-fit position, the >100 MeV flux upper limit (95% confidence) is <1.45e-10 ph cm^-2 s^-1 for ~16-years (2008-08-04 / T0), <9.80e-09(<5.72e-08) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0. In the analysis of the ~16-years integrated LAT data (100 MeV - 1 TeV), a 4.9 sigma excess of gamma rays, Fermi J1220.3+0200, was detected 0.73 deg offset from the best-fit IC241224A position, outside the 90% confidence localization of the direction of the neutrino. Assuming a power-law spectrum, the best-fit localization is (J2000) RA: 185.09 deg, Dec: 2.04 deg (9.40 arcmin 99% containment, 4.6 arcmin 68% containment). The gamma-ray best-fit spectral parameters are flux = (1.25 +/- 0.65)e-9 ph cm^-2 s^-1 and index = 2.08+/-0.19 (statistical uncertainty only). In a preliminary analysis of the LAT data over 1-day and 1-month prior T0, Fermi J1220.3+0200 is not significantly detected. The statistical significance is calculated following the prescription adopted in the Fourth Fermi-LAT catalog (The Fermi-LAT collaboration 2022, ApJS, 260, 53). The LAT catalogued object 2FGL J1219.7+0201 (The Fermi-LAT collaboration 2011, ApJ, 743, 171) is positionally consistent with Fermi J1220.3+0200 (2.7 arcmin separation). A possible counterpart is the blazar 5BZQJ1220+0203 (PKS 1217+02) at RA= 185.0495 deg, Dec= 2.0617 deg (Massaro et al. 2015 Ap&SS, 357, 1). The blazar is within the 68% positional uncertainty of Fermi J1220.3+0200, located 3 arcmin away from the gamma-ray best-fit position. Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this source will continue. For this source, the Fermi-LAT contact person is L. Pfeiffer (leonard.pfeiffer at stud-mail.uni-wuerzburg.de). The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. View this GCN Circular online at https://gcn.nasa.gov/circulars/39005. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37012] GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
by GCN Circulars 21 Jan '25

21 Jan '25

TITLE: GCN CIRCULAR NUMBER: 39004 SUBJECT: GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst DATE: 25/01/21 01:41:02 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 250118A onboard (T0: 2025-11-18T18:31:11.97 UTC, Fermi GCN 38976) 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 13.4 in a 0.128 s analysis time bin, starting at T0 - 0.064 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 7,422 deg2 and the 50% credible area is 1,652 deg2. The integrated probability inside the coded field of view is <1%. The NITRATES skymap is consistent with the Fermi localization reported in GCN 38976. The joint NITRATES+Fermi 90% credible area is 565 deg2 and the 50% credible area is 111 deg2 A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=758917906/#:~:te… The probability skymap file can be downloaded from the link here [skymap_fits_file](https://guano.swift.psu.edu/files/758917906/0_n_PROBMAP) 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=758917906 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/39004. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37011] GRB 250119B: Fermi GBM Observation
by GCN Circulars 20 Jan '25

20 Jan '25

TITLE: GCN CIRCULAR NUMBER: 39003 SUBJECT: GRB 250119B: Fermi GBM Observation DATE: 25/01/20 16:45:38 GMT FROM: Utkarsh Pathak at IIT Bombay <utkarshpathak.07(a)gmail.com> U. Pathak (IITB), R. Sonawane (IISER, TVM), and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 08:27:01.67 UT on 19 January 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250119B (trigger 758968026/250119352) which was also detected by INTEGRAL/SPI-ACS (Barria et al. 2025, GCN 38997). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 306.74, Dec = 21.23 (J2000 degrees, equivalent to J2000 20h 26m, +21d 13'), 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 106 degrees. The GBM light curve consists of two emission episodes with multiple spikes for a duration (T90) of about 255.5 s (50-300 keV). The time-averaged spectrum from T0-4 to T0+300 s is best fit by a Band function with Epeak = 297 +/- 14 keV, alpha = -0.98 +/- 0.02, and beta = -2.6 +/- 0.2. The event fluence (10-1000 keV) in this time interval is (9.2 +/- 0.1)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+44 s in the 10-1000 keV band is 17.6 +/- 0.4 ph/s/cm^2. A power law function with an exponential high-energy cutoff fits the spectrum equally well with Epeak= 314 +/- 11 keV, and alpha = -0.99 +/- 0.02. 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/39003. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37010] EP250108a/AT2025kg: 1.3m DFOT Optical observations
by GCN Circulars 20 Jan '25

20 Jan '25

TITLE: GCN CIRCULAR NUMBER: 39002 SUBJECT: EP250108a/AT2025kg: 1.3m DFOT Optical observations DATE: 25/01/20 16:38:19 GMT FROM: Amit Kumar Ror at ARIES <mitturor77894(a)gmail.com> Amit K. Ror, Anshika Gupta, Kiran, Shashi B. Pandey, Kuntal Mishra (ARIES) report: We observed the field of EP250108a detected by the Wide-field X-ray Telescope on board the Einstein Probe (Einstein Probe team, Li et al. 2025, GCN 38861), with the 1.3m Devasthal Fast Optical Telescope (DFOT), located at the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2025-01-19 at 16:15:38 UT, i.e., ~ 11.16 days after the Einstein Probe trigger. We have taken multiple frames with an exposure time of 300 s in the R filter. We stacked the images after the alignment. We detected an optical emission in our stacked image at the position of the optical counterpart candidate EP250108a / AT 2025kg by Eyles-Ferris et al. (2025, GCN 38878). We obtain the following preliminary magnitude in the stacked image: Date Start_UT T_start-T0 (days) Filter Exp time (s) Magnitude ================================================== 2025-01-19 16:15:38 ~11.16 R 300s*12 19.89 +/- 0.04 Our detection is consistent with Lipunov et al. 2025, GCN 38865; Eyles-Ferris et al. 2025, GCN 38878; Zhu et al. 2025, GCN 38885; Junjie-Jin et al. 2025, GCN 38891; Malesani et al. 2025, GCN 38902; Kumar et al. 2025, GCN 38907; Zhu et al. 2025, GCN 38908; Levan et al. 2025, GCN 38909; Izzo et al. 2025, GCN 38912; Zou et al. 2025, GCN 38914; Moskvitin et al. 2025, GCN 38925; Zhu et al. 2025, GCN 38937; Carotenuto et al. 2025, GCN 38958; Schroeder et al. 2025, GCN 38970; Song et al. 2025, GCN 38972; Eyles-Ferris et al. 2025, GCN 38983; Xu et al. 2025, GCN 38984; Levan et al. 2025, GCN 38987; and Tao et al. 2025, GCN 38998. The magnitude is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalogue. This circular may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/39002. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37009] Konus-Wind detection of GRB 250117A
by GCN Circulars 20 Jan '25

20 Jan '25

TITLE: GCN CIRCULAR NUMBER: 39001 SUBJECT: Konus-Wind detection of GRB 250117A DATE: 25/01/20 16:32:53 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 250117A (GECAM-B detection: Wang et al., GCN 38982; Swift/BAT-GUANO localization: DeLaunay et al., GCN 38988; SVOM/GRM detection: Wang et al., GCN 38994; IPN triangulation: Ridnaia et al., GCN 39000) triggered Konus-Wind at T0=73313.657 s UT (20:21:53.657). The burst light curve shows a weak count rate increase (from ~T0-0.412 s to ~T0-0.288) followed by a bright, multi-peaked pulse, which starts at ~T0-0.126 s and has a duration of ~0.138 s. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250117_T73313/ As observed by Konus-Wind, the burst had the total fluence of 7.70(-0.02,+2.44)x10^-7 erg/cm^2 and a 16-ms peak flux, measured from T0-0.008 s, of 1.87(-0.25,+0.64)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range). Since a major part of the burst emission was detected before the trigger time, the spectral analysis was performed using the KW 3-channel light curve data. Modelling the KW 3-channel spectrum of the main pulse (measured from T0-0.126 s to T0+0.012 s) by a power law with exponential cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), yields alpha = 0.52 (-0.54, + 0.75) and Ep = 459(-62,+84) keV. All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/39001. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 37008] IPN triangulation of GRB 250117A (short)
by GCN Circulars 20 Jan '25

20 Jan '25

TITLE: GCN CIRCULAR NUMBER: 39000 SUBJECT: IPN triangulation of GRB 250117A (short) DATE: 25/01/20 15:24:12 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, 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, E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, report: The short-duration GRB 250117A (GECAM-B detection: Wang et al., GCN 38982; Swift/BAT-GUANO localization: DeLaunay et al., GCN 38988; SVOM/GRM detection: Wang et al., GCN 38994) was detected by Konus-Wind, Fermi (GBM), INTEGRAL (SPI-ACS), Swift (BAT), GECAM-B, and SVOM (GRM), at about 73318 s UT (20:21:58). 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: 249.314 (16h 37m 15s) -26.387 (-26d 23' 13") Corners: 249.983 (16h 39m 56s) -33.454 (-33d 27' 16") 248.910 (16h 35m 38s) -28.572 (-28d 34' 20") 250.252 (16h 41m 01s) -19.117 (-19d 07' 02") 249.847 (16h 39m 23s) -24.228 (-24d 13' 41") --------------------------------------------- The error box area is 5.4 sq. deg, and its maximum dimension is 14.3 deg (the minimum one is 36 arcmin). The Sun distance was 46 deg. This localization may be improved. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB250117_T73313/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/39000. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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