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

[vsnet-grb-info 34409] LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
by GCN Circulars 29 May '24

29 May '24

TITLE: GCN CIRCULAR NUMBER: 36565 SUBJECT: LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations DATE: 24/05/29 16:29:35 GMT FROM: Nidhal Guessoum at AUS, UAE <nguessoum(a)aus.edu> S. Karpov (FZU), M. Prouza (FZU), M. Masek (FZU), H. Peng (THU), W. Corradi (LNA), A. Le Calloch (UCB), N. Guessoum (AUS), S. Antier (OCA), C. Andrade (UMN), M. Coughlin (UMN), P. Hello (IJCLAB), P.A Duverne (APC), T. Pradier (Unistra/IPHC), D. Turpin (CEA-Saclay/Irfu) Report on behalf of the GRANDMA collaboration: Coordinated through Skyportal (https://skyportal-icare.ijclab.in2p3.fr/) we performed tiled observations of LIGO/VIRGO event S240527fv (GCN 36551) with the FRAM-Auger (30cm ODK + CCD MII G4-16000, 60' x 60' field of view, Pierre Auger Observatory, Malargue, Argentina) telescope. Observations were conducted from 2024-04-29 08:10:26.076 to 2024-04-28 09:46:05.081, beginning approximately 33.0 hr after the GW trigger time, under moderate weather conditions. Using the Bilby skymap as a reference, we searched 43.7% (e.g 20.6 sq deg) of the localization region, acquiring 40 consecutive 2-minute long exposures in Johnson R filter at the individual pointings as described below: +------------+--------------+----------+----------+-----------+ | Date | Time | Filter | Exposure | Limiting | | | (UTC) | | (s) | Magnitude | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:10:26.076 | R | 120.0 | 14.91 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:12:37.678 | R | 120.0 | 14.56 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:15:00.776 | R | 120.0 | 14.34 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:17:12.432 | R | 120.0 | 13.64 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:19:33.063 | R | 120.0 | 14.16 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:21:44.737 | R | 120.0 | 14.22 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:24:05.386 | R | 120.0 | 15.34 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:26:16.903 | R | 120.0 | 15.62 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:28:37.672 | R | 120.0 | 14.26 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:30:49.260 | R | 120.0 | 14.34 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:33:10.230 | R | 120.0 | 13.83 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:35:21.850 | R | 120.0 | 13.21 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:37:43.128 | R | 120.0 | 13.72 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:39:54.712 | R | 120.0 | 12.58 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:42:16.535 | R | 120.0 | 12.65 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:44:28.200 | R | 120.0 | 12.36 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:46:47.697 | R | 120.0 | 12.82 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:48:59.325 | R | 120.0 | 13.57 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:51:21.246 | R | 120.0 | 12.53 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:53:32.809 | R | 120.0 | 12.76 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:55:55.340 | R | 120.0 | 13.66 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 08:58:06.955 | R | 120.0 | 14.50 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:00:27.858 | R | 120.0 | 14.38 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:02:39.495 | R | 120.0 | 14.67 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:05:01.103 | R | 120.0 | 14.53 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:07:12.729 | R | 120.0 | 14.98 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:09:36.377 | R | 120.0 | 14.56 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:11:47.928 | R | 120.0 | 15.08 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:14:08.980 | R | 120.0 | 15.69 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:16:20.612 | R | 120.0 | 15.51 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:18:43.580 | R | 120.0 | 15.34 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:20:55.200 | R | 120.0 | 15.61 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:30:19.249 | R | 120.0 | 15.17 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:32:30.827 | R | 120.0 | 14.81 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:34:50.198 | R | 120.0 | 15.26 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:37:01.946 | R | 120.0 | 14.94 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:39:22.748 | R | 120.0 | 15.20 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:41:34.360 | R | 120.0 | 15.29 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:43:53.433 | R | 120.0 | 15.33 | |------------+--------------+----------+----------+-----------+ | 2024-05-29 | 09:46:05.081 | R | 120.0 | 15.30 | |------------+--------------+----------+----------+-----------+ Our low latency analysis (Karpov et al. 2021) did not reveal any significant candidate down to the limits listed in the table above (5 sigma, AB system). GRANDMA (Global Rapid Advanced Network Devoted to the Multi-messenger Addicts) is a network of robotic telescopes connected all over the world with both photometry and spectrometry capabilities for Time- domain Astronomy (https://grandma.lal.in2p3.fr/) Details on the FRAM telescopes are available on the GRANDMA web pages or on https://grandma.ijclab.in2p3.fr/fram/ View this GCN Circular online at https://gcn.nasa.gov/circulars/36565. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34408] GRB 240529A: Swift-XRT refined Analysis
by GCN Circulars 29 May '24

29 May '24

TITLE: GCN CIRCULAR NUMBER: 36564 SUBJECT: GRB 240529A: Swift-XRT refined Analysis DATE: 24/05/29 14:50:35 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Dichiara (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), A. Tohuvavohu (U. Toronto) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 5.8 ks of XRT data for GRB 240529A, from 107 s to 19.1 ks after the BAT trigger. The data comprise 344 s in Windowed Timing (WT) mode (the first 10 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.945 (+0.015, -0.025). The best-fitting absorption column is consistent with the Galactic value of 4.1 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.07 (+0.05, -0.04) and a best-fitting absorption column consistent with the Galactic value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (6.0 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 4.06 (+0.15, -0.00) x 10^21 cm^-2 Galactic foreground: 4.1 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 2.07 (+0.05, -0.04) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01231488. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/36564. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34407] GRB240529A: BOOTES-6/DPRT optical detection
by GCN Circulars 29 May '24

29 May '24

TITLE: GCN CIRCULAR NUMBER: 36563 SUBJECT: GRB240529A: BOOTES-6/DPRT optical detection DATE: 24/05/29 13:24:36 GMT FROM: Youdong HU at INAF-OAB <huyoudong072(a)hotmail.com> I. Perez-Garcia, E. Fernandez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, S.-Y. Wu and A. J. Castro-Tirado (IAA-CSIC, Granada), Y.-D. Hu (INAF-OAB), P. J. Meintjes and H. J. van Heerden (UFS, South Africa), A. Martin-Carrillo and L. Hanlon (UCD, Ireland), C. J. Perez del Pulgar (UMA, Malaga) and D.-R. Xiong (YNAO) on behalf of a larger collaboration, report: Following the detection of GRB 240529A by Swift (Eyles-Ferris et al. GCNC 36556), the BOOTES-6/DPRT 0.6m robotic telescope at Boyden Observatory in Maselspoort (South Africa) observed the GRB location starting on May. 29, 03:05 UT (~ 7 min after trigger). A series of images in clear filter were gathered and the optical afterglow was detected within the enhanced Swift/XRT position (Osborne et al. GCNC 36557) for which we measure a preliminary magnitude of 15.2 +- 0.1 on the first co-added 10 s x 4 image, which is consistent with the detections of GOTO (Kumar et al. GCNC 36559), NOT (Fu et al. GCNC 36561) and UVOT (Shilling et al. GCNC 36562). Further imaging is ongoing. We thank the staff at Boyden Observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/36563. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34406] GRB 240529A: Swift/UVOT Detection
by GCN Circulars 29 May '24

29 May '24

TITLE: GCN CIRCULAR NUMBER: 36562 SUBJECT: GRB 240529A: Swift/UVOT Detection DATE: 24/05/29 13:07:35 GMT FROM: Sam Shilling at Lancaster University <shilling.sam(a)gmail.com> S.P.R. Shilling (Lancaster U.) and Eyles-Ferris (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 240529A 128 s after the BAT trigger (Eyles-Ferris et al., GCN Circ. 36556). A source consistent with the enhanced XRT position (Osborne et al., GCN Circ. 36557) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 22:21:25.97 = 335.35822 (deg.) Dec (J2000) = +51:33:43.0 = 51.56194 (deg.) with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 128 278 147 17.07 +/- 0.04 v 671 691 19 16.16 +/- 0.14 b 598 617 19 17.44 +/- 0.16 u 341 591 246 18.27 +/- 0.10 w1 720 1642 97 >18.8 m2 695 1617 97 >18.7 w2 647 1568 117 >19.1 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.332 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/36562. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34405] GRB 240529A: NOT optical observations
by GCN Circulars 29 May '24

29 May '24

TITLE: GCN CIRCULAR NUMBER: 36561 SUBJECT: GRB 240529A: NOT optical observations DATE: 24/05/29 10:55:16 GMT FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn> S.Y. Fu, J. An, Z.P. Zhu, X. Liu, S.Q. Jiang, D. Xu (NAOC), D. B. Malesani (DAWN/NBI and Radboud), J. Terwel (NOT) report on behalf of a large collaboration: We observed the field of GRB 240529A detected by Swift (Eyles-Ferris et al., GCN 36556) using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera, and obtained 3 x 100 s frames in the Sloan r-band and 3 x 100 s frames in z-band, starting at 04:51:50.7 UT on 2024-05-29, i.e., 1.89 hr after the BAT trigger. The optical afterglow (Eyles-Ferris et al., GCN 36556; Kumar et al. GCN 36559) of the burst is clearly detected in our stacked images. Preliminary photometry results are as follows: Tmid (UT) Tmid-T0(hr) Mag MagErr Filter 2024-05-29T04:54:47 1.94 16.48 0.05 r 2024-05-29T05:01:30 2.05 15.40 0.05 z calibrated with nearby PanSTARRS stars. View this GCN Circular online at https://gcn.nasa.gov/circulars/36561. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34404] GRB 240529A: AstroSat CZTI detection
by GCN Circulars 29 May '24

29 May '24

TITLE: GCN CIRCULAR NUMBER: 36560 SUBJECT: GRB 240529A: AstroSat CZTI detection DATE: 24/05/29 09:32:31 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in> J. Joshi (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long-duration GRB 240529A which was also detected by Swift-BAT (Eyles-Ferris et al., GCN Circ. 36556). The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2024-05-29 02:58:30.46 UTC. The measured peak count rate associated with the burst is 372 (+67, -60) counts/s above the background in the combined data of all quadrants, with a total of 6548 (+660, -731) counts. The local mean background count rate was 1334 (+5, -6) counts/s. We measure a T90 of 40 (+-2) s from the cumulative Veto light curve. The source was also faintly detected in the CZT detectors in the 20-200 keV energy range. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/36560. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34403] GRB 240529A: GOTO optical afterglow detection
by GCN Circulars 29 May '24

29 May '24

TITLE: GCN CIRCULAR NUMBER: 36559 SUBJECT: GRB 240529A: GOTO optical afterglow detection DATE: 24/05/29 07:47:25 GMT FROM: Amit Kundu at University of Warwick, UK <amitkundu515(a)gmail.com> A. Kumar, B. P. Gompertz, S. Belkin, G. Ramsay, Y. Julakanti, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, F. Jimenez-Ibarra, D. O'Neill, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, E. Palle and D. Pollacco report on behalf of the GOTO collaboration: The Gravitational-wave Optical Transient Observer (GOTO, Steeghs et al., 2022) performed targeted observations in response to Swift-detected GRB 240529A (Eyles-Ferris et al., GCN 36556). Three epochs of targeted observations were performed by GOTO-North starting at 2024-05-29UT03:02:10.4 (3.67 minutes after the trigger). The first two targeted observations consisted of 4x90s exposures in the GOTO L-band (400-700 nm), whereas the third pointing was covered during the serendipitous survey pointing and had exposure times of 4x45 sec. We detect the optical afterglow in all three epochs, with L-band magnitudes of 16.06 +/- 0.01, 17.55 +/- 0.03 and 17.30 +/- 0.04 at 4.5 minutes, 1.22 hours and 1.72 hours (mid-points) after trigger, respectively. Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/36559. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34402] GRB 240527B: Swift-XRT afterglow detection
by GCN Circulars 29 May '24

29 May '24

TITLE: GCN CIRCULAR NUMBER: 36558 SUBJECT: GRB 240527B: Swift-XRT afterglow detection DATE: 24/05/29 05:53:44 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J. D. Gropp (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 240527B, collecting 5.2 ks of Photon Counting (PC) mode data between T0+27.3 ks and T0+135.5 ks. Eight uncatalogued X-ray sources are detected, of which one ("Source 7") is above the RASS 3-sigma upper limit at this position and fading with >3-sigma significance, and is therefore likely the GRB afterglow. Using 1624 s of PC mode data and 3 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 128.15387, -14.43738 which is equivalent to: RA (J2000): 08h 32m 36.93s Dec(J2000): -14d 26' 14.6" with an uncertainty of 2.0 arcsec (radius, 90% confidence). This position is 4.0 arcmin from the Fermi/LAT position. The light curve can be modelled with a power-law decay with a decay index of alpha=1.23 (+0.16, -0.14). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.70 (+0.08, -0.06). The best-fitting absorption column is consistent with the Galactic value of 5.7 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (4.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 5.7 (+/-1.9) x 10^20 cm^-2 Galactic foreground: 5.7 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.70 (+0.08, -0.06) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00021694. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021694. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/36558. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34401] GRB 240529A: Enhanced Swift-XRT position
by GCN Circulars 29 May '24

29 May '24

TITLE: GCN CIRCULAR NUMBER: 36557 SUBJECT: GRB 240529A: Enhanced Swift-XRT position DATE: 24/05/29 05:48:24 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 1384 s of XRT Photon Counting mode data and 1 UVOT images for GRB 240529A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 335.35741, +51.56166 which is equivalent to: RA (J2000): 22h 21m 25.78s Dec (J2000): +51d 33' 42.0" with an uncertainty of 2.2 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/36557. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 34400] GRB 240529A: Swift detection of a burst with an optical counterpart
by GCN Circulars 29 May '24

29 May '24

TITLE: GCN CIRCULAR NUMBER: 36556 SUBJECT: GRB 240529A: Swift detection of a burst with an optical counterpart DATE: 24/05/29 03:38:03 GMT FROM: David Palmer at LANL <palmer(a)lanl.gov> R. A. J. Eyles-Ferris (U Leicester), R. Gupta (NASA/GSFC), A. Y. Lien (U Tampa), K. L. Page (U Leicester), D. M. Palmer (LANL) and T. M. Parsotan (GSFC) report on behalf of the Neil Gehrels Swift Observatory Team: At 02:58:31 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 240529A (trigger=1231488). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 335.322, +51.555 which is RA(J2000) = 22h 21m 17s Dec(J2000) = +51d 33' 19" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of at least 20 sec since we are missing data after ~8 sec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 03:06:22.0 UT, 471.2 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 335.35696, 51.56207 which is equivalent to: RA(J2000) = 22h 21m 25.67s Dec(J2000) = +51d 33' 43.5" with an uncertainty of 3.5 arcseconds (radius, 90% containment). This location is 82 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 4.06 x 10^21 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 128 seconds after the BAT trigger. There is a candidate afterglow in the list of sources generated on-board at RA(J2000) = 22:21:26.04 = 335.35851 DEC(J2000) = +51:33:43.4 = 51.56205 with a 90%-confidence error radius of about 1.10 arc sec. This position is 2.7 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.84. No correction has been made for the large, but uncertain, extinction expected. Burst Advocate for this burst is R. A. J. Eyles-Ferris (raje1 AT leicester.ac.uk). 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/36556. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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