July 2024 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 34669] LIGO/Virgo/KAGRA S240703ad: Identification of a GW compact binary merger candidate
by GCN Circulars 03 Jul '24

03 Jul '24

TITLE: GCN CIRCULAR NUMBER: 36816 SUBJECT: LIGO/Virgo/KAGRA S240703ad: Identification of a GW compact binary merger candidate DATE: 24/07/03 19:51:51 GMT FROM: andrei.danilin(a)LIGO.ORG The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S240703ad during real-time processing of data from LIGO Livingston Observatory (L1) and Virgo Observatory (V1) at 2024-07-03 19:13:55.283 UTC (GPS time: 1404069253.283). The candidate was found by the GstLAL [1] analysis pipeline. S240703ad is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.2e-13 Hz, or about one in 1e5 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S240703ad The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%). Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [2] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [2] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [3], distributed via GCN notice about 31 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [3], distributed via GCN notice about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 11463 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2724 +/- 923 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625 [2] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [3] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/36816. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34668] EP240703a/GRB 240703A: TRT and JinShan decaying optical afterglow candidate
by GCN Circulars 03 Jul '24

03 Jul '24

TITLE: GCN CIRCULAR NUMBER: 36815 SUBJECT: EP240703a/GRB 240703A: TRT and JinShan decaying optical afterglow candidate DATE: 24/07/03 18:28:56 GMT FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn> J. An, S.Q. Jiang (NAOC), S. Tinyanont, R. Anutarawiramkul, P. Butpan (NARIT), X. Liu, S.Y. Fu, Z.P. Zhu, D. Xu, Z. Fan, W.X. Li, N.C. Sun, Y.N. Wang (NAOC) report on behalf of a large collaboration: We observed the field of the X-ray transient, EP240703a, detected by EP/WXT (Wang et al., GCN 36807), and also by Konus-Wind (Frederiks et al., GCN 36809), thus confirming that it is likely GRB 240703A, using the Thai Response Telescope (TRT) SBO node and the JinShan 100C & 50A telescopes. Image subtraction of the stacked 5 x 360 s R-band TRT image against the PanSTARRS archival r-band image reveals multiple optical afterglow candidates, among which an uncatalogued optical transient (OT) is localized at coordinates R.A. (J2000) = 18:15:03.89 Dec. (J2000) = -09:42:02.96 with an uncertainty of ~ 0.5 arcsec. The OT has r ~ 20.4 +/- 0.1 mag at a median time of ~ 13.9 hr post-trigger, calibrated with nearby PanSTARRS stars and not corrected for Galactic extinction of A_r ~ 3 mag. We then obtained 10 x 300 s frames in the Sloan r-band and 10 x 300 s in the Sloan z-band at the JinShan 100C telescope. The OT is not detected in the stacked r-band image down to r ~ 22.2 mag at a median time of 16.07 hr post-trigger, also not detected in z-band down to z ~ 20.6 mag at a median time of 16.91 hr post-trigger, both calibrated with the nearby PanSTARRS field. The presence and the decay of the OT make it an optical afterglow candidate of EP240703a/GRB 240703A. View this GCN Circular online at https://gcn.nasa.gov/circulars/36815. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34667] IPN triangulation of GRB 240627A
by GCN Circulars 03 Jul '24

03 Jul '24

TITLE: GCN CIRCULAR NUMBER: 36814 SUBJECT: IPN triangulation of GRB 240627A DATE: 24/07/03 17:35:46 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(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. Ridnaia, A. Lysenko, 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, S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, G. Waratkar, V. Jethwani, 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 bright, long-duration GRB 240627A (AstroSat-CZTI detection: Joshi et al., GCN 36776; NuSTAR anti-coincidence shields detection: Grefenstette, GCN 36778; CALET-CGBM detection: Kobayashi et al., GCN 36798) was detected by Astrosat (CZTI), Konus-Wind, INTEGRAL (SPI-ACS), NuSTAR (ACS), CALET (CGBM), and Mars-Odyssey (HEND) at about 86341 s UT (23:59:01). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 164.155 (10h 56m 37s) +72.806 (+72d 48' 23") Corners: 166.270 (11h 05m 05s) +73.674 (+73d 40' 25") 166.346 (11h 05m 23s) +73.611 (+73d 36' 38") 162.228 (10h 48m 55s) +71.917 (+71d 55' 02") 162.147 (10h 48m 35s) +71.979 (+71d 58' 45") --------------------------------------------- The error box area is 416 sq. arcmin, and its maximum dimension is 2.1 deg (the minimum one is 3.4 arcmin). The Sun distance was 60 deg. This localization may be improved. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB240627_T86332/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/36814. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34666] GRB 240619A: Host galaxy redshift from VLT/X-shooter
by GCN Circulars 03 Jul '24

03 Jul '24

TITLE: GCN CIRCULAR NUMBER: 36813 SUBJECT: GRB 240619A: Host galaxy redshift from VLT/X-shooter DATE: 24/07/03 15:58:09 GMT FROM: Laura Cotter <laura.cotter(a)ucdconnect.ie> L. Cotter (UCD), B. Schneider (MIT), D. Xu (NAOC), J. T. Palmerio (GEPI, Obs. de Paris), D. B. Malesani (DAWN/NBI and Radboud Univ.), A. de Ugarte Postigo (CNRS, OCA, LAM), G. Pugliese (Amsterdam), B. P. Gompertz (Birmingham), A. Martin-Carrillo (UCD), A. Rossi (INAF), D. Hartmann (Clemson Univ.), T. Aishwarya (INAF), N. R. Tanvir (Leicester), A. J. Levan (Radboud) report on behalf of the Stargate collaboration: We observed the location (Gompertz et al., GCN 36715; Capalbi et al., GCN 36721; Mo et al., GCN 36739; Rhodes et al., GCN 36744) of the Fermi GRB 240619A (Fermi GBM team, GCN 36694; Preis et al., GCN 36695; Dalessi et al., GCN 36717) using the X-shooter spectrograph mounted on the ESO VLT UT3 (Melipal). The observation was performed on 2024 July 02 (13.8 days after the GRB). It consisted of 4 exposures of 600 s each and covered the wavelength range 3000-21000 AA. The target is faintly detected in the r-band acquisition image, with an AB magnitude r ~ 22.8 (calibration is difficult due to paucity of calibrators in the field). This is significantly brighter than the archival object visible in the Pan-STARRS and Legacy surveys, first noticed by Gompertz et al. (GCN 36715), and likely includes a transient contribution. In a preliminary reduction, we detect several strong emission lines that we identify as H-alpha, H-beta, H-gamma, the [O II] doublet, [O III] 4959, [O III] 5007, and [Ne III] 3869 at a common redshift of z = 0.3965, which is lower than the photometric value reported in the PS1-STRM catalog (Beck et al. 2020) for galaxy PSO J162.3946+17.2828. We therefore propose this to be the redshift of the GRB. The Legacy survey images also show a second, fainter object about 1.7" west of the optical afterglow position. This was also included in the slit, and we measure for it z = 1.338 from detection of [O II] and H-alpha. Given the larger offset, we consider this galaxy to be unrelated to the GRB. We acknowledge expert support from the ESO staff in Paranal, in particular Matias Jones and Thomas Szeifert. View this GCN Circular online at https://gcn.nasa.gov/circulars/36813. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34665] GRB 240619A: Host galaxy redshift from VLT/X-shooter
by GCN Circulars 03 Jul '24

03 Jul '24

TITLE: GCN CIRCULAR NUMBER: 36813 SUBJECT: GRB 240619A: Host galaxy redshift from VLT/X-shooter DATE: 24/07/03 15:58:09 GMT FROM: Laura Cotter <laura.cotter(a)ucdconnect.ie> L. Cotter (UCD), B. Schneider (MIT), D. Xu (NAOC), J. T. Palmerio (GEPI, Obs. de Paris), D. B. Malesani (DAWN/NBI and Radboud Univ.), A. de Ugarte Postigo (CNRS, OCA, LAM), G. Pugliese (Amsterdam), B. P. Gompertz (Birmingham), A. Martin-Carrillo (UCD), A. Rossi (INAF), D. Hartmann (Clemson Univ.), T. Aishwarya (INAF), N. R. Tanvir (Leicester), A. J. Levan (Radboud) report on behalf of the Stargate collaboration: We observed the location (Gompertz et al., GCN 36715; Capalbi et al., GCN 36721; Mo et al., GCN 36739; Rhodes et al., GCN 36744) of the Fermi GRB 240619A (Fermi GBM team, GCN 36694; Preis et al., GCN 36695; Dalessi et al., GCN 36717) using the X-shooter spectrograph mounted on the ESO VLT UT3 (Melipal). The observation was performed on 2024 July 02 (13.8 days after the GRB). It consisted of 4 exposures of 600 s each and covered the wavelength range 3000-21000 AA. The target is faintly detected in the r-band acquisition image, with an AB magnitude r ~ 22.8 (calibration is difficult due to paucity of calibrators in the field). This is significantly brighter than the archival object visible in the Pan-STARRS and Legacy surveys, first noticed by Gompertz et al. (GCN 36715), and likely includes a transient contribution. In a preliminary reduction, we detect several strong emission lines that we identify as H-alpha, H-beta, H-gamma, the [O II] doublet, [O III] 4959, [O III] 5007, and [Ne III] 3869 at a common redshift of z = 0.3965, which is lower than the photometric value reported in the PS1-STRM catalog (Beck et al. 2020) for galaxy PSO J162.3946+17.2828. We therefore propose this to be the redshift of the GRB. The Legacy survey images also show a second, fainter object about 1.7" west of the optical afterglow position. This was also included in the slit, and we measure for it z = 1.338 from detection of [O II] and H-alpha. Given the larger offset, we consider this galaxy to be unrelated to the GRB. We acknowledge expert support from the ESO staff in Paranal, in particular Matias Jones and Thomas Szeifert. View this GCN Circular online at https://gcn.nasa.gov/circulars/36813. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34664] LIGO/Virgo/KAGRA S240422ed: Updated significance estimate
by GCN Circulars 03 Jul '24

03 Jul '24

TITLE: GCN CIRCULAR NUMBER: 36812 SUBJECT: LIGO/Virgo/KAGRA S240422ed: Updated significance estimate DATE: 24/07/03 15:49:54 GMT FROM: Ryan Magee at LVC <ryan.magee(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data, obtaining an improved estimate for the significance of compact binary merger (CBC) candidate S240422ed (GCN Circular 36236) by including information from subsequent data in the background model. The updated background estimate from the GstLAL [1] pipeline results in a reduced significance of the candidate. As a result, the highest significance estimated for this candidate is now a false alarm rate of 3.269e-07 Hz, or about one in thirty five days, which was obtained by the PyCBC Live analysis in low latency. Both GstLAL [1] and PyCBC Live [2] analyses now find this event as a low-significance candidate. The MBTA [3] low-latency analysis finds the false alarm rate of the candidate to not pass the low-significance threshold. The updated classification of the candidate, in order of descending probability, is Terrestrial (93%), BNS (5%), NSBH (2%), or BBH (<1%). Note that future offline analyses may infer a different terrestrial probability and/or false alarm rate. For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625 [2] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [3] Aubin et al. CQG 38, 095004 (2021) doi:10.1088/1361-6382/abe913 View this GCN Circular online at https://gcn.nasa.gov/circulars/36812. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34663] The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
by GCN Circulars 03 Jul '24

03 Jul '24

TITLE: GCN CIRCULAR NUMBER: 36811 SUBJECT: The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT DATE: 24/07/03 15:23:07 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> C. Y. Dai (NJU), J. Q. Peng, Q. C. Shui (IHEP, CAS), Y. L. Wang, C. C. Jin, Z. X. Ling, W. Yuan, Y. Liu, C. Zhang, H. Q. Cheng, C. Z. Cui, D. W. Fan, H. B. Hu, J. W. Hu, M. H. Huang, D. Y. Li, H. Y. Liu, M. J. Liu, Z. Z. Lv, T. Y. Lian, X. Mao, H. W. Pan, X. Pan, H. Sun, W. X. Wang, Y. L. Wang, S. X. Wen, Q. Y. Wu, X. P. Xu, Y. F. Xu, H. N. Yang, M. Zhang, W. D. Zhang, W. J. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), Y. Chen, S. M. Jia, S. N. Zhang (IHEP, CAS), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (Univ. of Leicester), K. Nandra, A. Rau (MPE), B. Cordier (CEA) on behalf of the Einstein Probe team We report on the X-ray upper limits from the observations of the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, for the first three GRBs detected by SVOM (Xiong et al. GCN #36805), GRB 240627B, GRB 240629A and GRB 240702A. Among the three GRBs, the position of GRB 240702A has not been covered by the field-of-view of WXT after its detection by SVOM. Both GRB 240627B and GRB 240629A were serendipitously covered by the field-of-view of WXT multiple times after their detections by SVOM, but no new X-ray sources were found within 3 degrees of their positions. The flux upper limits at the 5-sigma confidence level for GRB 240627B and GRB 240629A are detailed as follows. Source | R.A | Dec. ｜ Obs. start time | Exposure (s) | Upper limit (erg/s/cm2) ------------------------------------------------------------------------------------------------------ GRB 240627B | 215.25 | 48.52 | 2024-06-27T20:21:43.000 | 586 | 4.43e-11 GRB 240627B | 215.25 | 48.52 | 2024-06-27T23:23:27.000 | 1233 | 2.90e-11 GRB 240629A | 314.4 | -35.7 | 2024-06-30T00:11:05.000 | 6429 | 1.18e-11 GRB 240629A | 314.4 | -35.7 | 2024-06-30T04:59:38.000 | 54140 | 3.93e-12 ------------------------------------------------------------------------------------------------------ The above observations were made with the WXT instrument during the commissioning phase of EP. 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). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES. View this GCN Circular online at https://gcn.nasa.gov/circulars/36811. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34662] EP240703b: EP-WXT detection of a fast X-ray transient
by GCN Circulars 03 Jul '24

03 Jul '24

TITLE: GCN CIRCULAR NUMBER: 36810 SUBJECT: EP240703b: EP-WXT detection of a fast X-ray transient DATE: 24/07/03 15:09:49 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> J. Q. Peng, Q. C. Shui (IHEP, CAS), C. Y. Dai (NJU), Y. L. Wang, C. C. Jin, Z. X. Ling, W. Yuan, Y. Liu, C. Zhang, H. Q. Cheng, C. Z. Cui, D. W. Fan, H. B. Hu, J. W. Hu, M. H. Huang, D. Y. Li, H. Y. Liu, M. J. Liu, Z. Z. Lv, T. Y. Lian, X. Mao, H. W. Pan, X. Pan, H. Sun, W. X. Wang, Y. L. Wang, S. X. Wen, Q. Y. Wu, X. P. Xu, Y. F. Xu, H. N. Yang, M. Zhang, W. D. Zhang, W. J. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), Y. Chen, S. M. Jia, S. N. Zhang (IHEP, CAS), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (Univ. of Leicester), K. Nandra, A. Rau (MPE), B. Cordier (CEA) on behalf of the Einstein Probe team We report on the detection of a fast X-ray transient, designated EP240703b, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient started at 2024-07-03T05:24:26 (UTC). The position of the source is R.A. = 279.539 deg, DEC = -57.401 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). The corresponding Galactic coordinates are l = 338.077, b = -20.878. The transient lasted for approximately 600 seconds and had a peak absorbed flux of ~ 3 x 10^-9 erg/s/cm^2 in the 0.5-4 keV band. The average 0.5-4 keV spectrum can be fitted by an absorbed power law with a column density of 1.4(+1.3/-1.2) x 10^21 cm^-2 and a photon index of 1.5(+0.6/-0.5). The derived average unabsorbed 0.5-4 keV flux is 7.5(+1.3/-1.8) x 10^-10 erg/s/cm^2. If the column density is fixed at the Galactic value of 6.8 x 10^20 cm^-2, the derived photon index is 1.2(+/-0.2) and the average unabsorbed 0.5-4 keV flux is 7.1(+1.1/-1.0) x 10^-10 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. No previously known X-ray sources at a similar flux level are found within the 3 arcmin region around the source position. We have proposed a Swift target of opportunity observation. Further follow-up observations are encouraged to identify the nature of this X-ray transient. The above observation was made with the WXT instrument during the commissioning phase of EP. 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). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES. View this GCN Circular online at https://gcn.nasa.gov/circulars/36810. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34661] Konus-Wind detection of GRB 240703A (a counterpart of EP240703a)
by GCN Circulars 03 Jul '24

03 Jul '24

TITLE: GCN CIRCULAR NUMBER: 36809 SUBJECT: Konus-Wind detection of GRB 240703A (a counterpart of EP240703a) DATE: 24/07/03 13:48:13 GMT FROM: Dmitry Frederiks at Ioffe Institute <fred(a)mail.ioffe.ru> D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: A long-duration GRB 240703A was detected by Konus-Wind (KW) in the waiting mode at ~00:38:32 UT. The burst source is located in the southern ecliptic hemisphere. Corrected for the propagation time, the burst was detected ~2 s before the start time of the fast X-ray transient EP240703a (T0=T0(EP)=00:38:40 UT; Wang et al., GCN 36807). The positional and temporal coincidence of this burst with the EP transient supports the conclusion that EP240315a is the GRB counterpart. A Bayesian block analysis of the KW waiting mode data in the 20-1250 keV band reveals a >12 sigma count rate increase in the interval from T0-2 s to T0+136 s. The burst light curve shows a multi-peaked structure with the brightest peak around ~T0+13 s. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB240703A/ The time-integrated spectrum of the burst, measured from T0-2 s to T0+136 s, is best described by a power law with exponential cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.09(-0.30,+0.47) and Ep = 180(-44,+62) keV. The spectrum near the peak count rate, measured from T0-2 s to T0+33 s, can be described by a CPL model with alpha = -0.75(-0.33,+0.41) and Ep = 276(-58,+81) keV. The total burst fluence is 1.36(-0.18,+0.18)x10^-5 erg/cm^2, and the 2.944 s peak energy flux, measured from T0+12.5 s, is 2.8(-0.4,+0.4)x10^-7 erg/cm^2. (both in the 20 keV - 10 MeV energy range). 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/36809. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34660] EP240702a: Swift/XRT upper limit
by GCN Circulars 03 Jul '24

03 Jul '24

TITLE: GCN CIRCULAR NUMBER: 36808 SUBJECT: EP240702a: Swift/XRT upper limit DATE: 24/07/03 13:31:10 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> W. Chen, X. P. Xu (NAOC, CAS), C. Y. Dai (NJU), S. X. Wen, Z. X. Ling, W. Yuan, Y. Liu, C. Zhang, C. C. Jin, H. Q. Cheng, C. Z. Cui, D. W. Fan, H. B. Hu, J. W. Hu, M. H. Huang, D. Y. Li, H. Y. Liu, M. J. Liu, Z. Z. Lv, T. Y. Lian, X. Mao, H. W. Pan, X. Pan, H. Sun, W. X. Wang, Y. L. Wang, Q. Y. Wu, Y. F. Xu, H. N. Yang, M. Zhang, W. D. Zhang, W. J. Zhang, Z. Zhang, D. H. Zhao (NAOC, CAS), Y. Chen, S. M. Jia, S. N. Zhang (IHEP, CAS), E. Kuulkers, A. Santovincenzo (ESA), P. O'Brien (Univ. of Leicester), K. Nandra, A. Rau (MPE), B. Cordier (CEA) on behalf of the Einstein Probe team Following the detection of the fast X-ray transient EP240702a by the Einstein Probe (Chen et al., GCN 36801), we performed a Swift target of opportunity observation (ObsID: 00016693001). The XRT onboard Swift began the observation at 2024-07-02T09:03:28 UTC, about 8 hours after the WXT detection, with an exposure time of 1950 s in the Photon Counting mode. No significant X-ray source was detected within the 3 arcmin region around the WXT position. Assuming an absorbed power-law model with a Galactic column density of 2.0 x 10^20 cm^-2 and a photon index of 1.1, the estimated flux upper limit in 0.3-10 keV at the 90% confidence level is 1.58 x 10^-13 ergs/cm^2/s. We thank the Neil Gehrels Swift Observatory team for making the X-ray observation possible. View this GCN Circular online at https://gcn.nasa.gov/circulars/36808. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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