//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21142 SUBJECT: GRB 170524B: Swift detection of a burst DATE: 17/05/25 18:29:03 GMT FROM: Amy Lien at GSFC S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), and T. Sakamoto (AGU), report on behalf of the Swift Team: At 10:40:40 UT on 2017-05-24, the Swift Burst Alert Telescope (BAT) triggered on GRB 170524B (trigger=754265). However, on-board analysis was truncated by a pre-planned slew to a scheduled target. Subsequent ground analysis using data from T+2 to T+101 s finds the source at a location of RA, Dec 90.864, -17.086, which is RA(J2000) = 06h 03m 27s Dec(J2000) = -17d 05' 11" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a complex structure about 50 seconds long. The raw peak count rate was ~18000 counts/sec (15-350 keV), at ~7 sec after the trigger. T90 (15-350 keV) estimated using the raw light curve is 46.4 +- 1.6 sec (estimated error including systematics). The time-averaged spectrum from T+1.8 to T+49.6 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.15 +- 0.06. The fluence in the 15-150 keV band is (6.6 +/- 0.2) x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+6.70 sec in the 15-150 keV band is 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. This event was also detected by CALET, KONUS-Wind, and INTEGRAL SPI ACS. A Swift Target of Opportunity observation has been requested. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/00753445006/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21144 SUBJECT: GRB 170524B: Swift ToO observations DATE: 17/05/25 19:51:17 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the Swift/BAT GRB 170524B. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/ToO_GRBs/00020775 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Swift/BAT event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21147 SUBJECT: GRB 170524B: MASTER-OAFA observations DATE: 17/05/26 09:42:12 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA), National University of San Juan, Argentina H. Levato, C. Saffe Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, D.Kuvshinov, A.V.Krylov, I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, O. Ershova Irkutsk State University V.Yurkov, Yu.Sergienko Blagoveschensk Educational State University, Blagoveschensk A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias MASTER robotic telescope (6 square degrees) located in OAFA was pointed to the GRB170525B (Barthelmy et al., GCN #21142) 15191 sec after notice time and 43294 sec after trigger time at 2017-05-25 22:42:14 UT. On our first (180s exposure) set we haven`t found optical transient within Master error-box (ra=90.8625 dec=-17.0861 r=0.1). The 5-sigma upper limit has been about 18.3 mag There is no OT at added images brighter 19.9 at Swift XRT position (Barthelmy et al., GCN #21142; Evans, GCN #21144 ). The observations made on zenit distance = 59 degrees, galaxy latitude b = -18 degree. The moon ( 0 % bright part) below the horizon (The altitude of the Moon is -8 degree ). Observations started at twilight. The sun altitude is -12.7 degree. The object can be observed till 2017-05-26 01:12:20 The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21148 SUBJECT: Konus-Wind observation of GRB 170524B DATE: 17/05/26 11:33:22 GMT FROM: Dmitry Frederiks at Ioffe Institute D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report: The long GRB 170524B (Swift/BAT detection: Barthelmy et al., GCN 21142) triggered Konus-Wind at T0=38438.475 s UT (10:40:38.475). The KW light curve shows a multi-peaked emission with a total duration of ~24 s. The emission is seen up to ~10 MeV. As observed by Konus-Wind, the burst had a fluence of (5.7 ± 0.4)x10^-5 erg/cm2 and a 64-ms peak energy flux, measured from T0+1.644, of (1.44 ± 0.10)x10^-5 erg/cm2 (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum (measured from T0 to T0+21.760 s) is best fit in the 20 keV - 15 MeV range by a cutoff power-law (CPL) function with the following model parameters: the photon index alpha = -0.85(-0.06,+0.06), and the peak energy Ep = 766(-74,+87) keV, chi2 = 93/98 dof. Fitting this spectrum with the GRB (Band) function yields the same alpha and Ep, and an upper limit on beta of -2.5, chi2 = 93/97 dof. The spectrum near the peak count rate (measured from T0 to T0+5.376 s) is best fit in the 20 keV - 15 MeV range by the CPL function with the following model parameters: the photon index alpha = -0.72(-0.06,+0.06), and the peak energy Ep = 860(-73,+83) keV, chi2 = 111/98 dof. Fitting this spectrum with the GRB (Band) function yields the same alpha and Ep, and an upper limit on beta of -2.7, chi2 = 110/97 dof. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB170524_T38438/ All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21150 SUBJECT: GRB 170524B: Swift-XRT observations DATE: 17/05/26 15:05:52 GMT FROM: Aaron Cholden-Brown at PSU/Swift A. Cholden-Brown (PSU), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), D.N. Burrows (PSU), S. J. LaPorte (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Swift/BAT-detected burst GRB 170524B (Barthelmy et al. GCN Circ. 21142), collecting 2.1 ks of Photon Counting (PC) mode data between T0+119.5 ks and T0+126.8 ks. One uncatalogued X-ray source has been detected consistent with being within 296 arcsec of the Swift/BAT position, it is below the RASS limit and shows no definitive signs of fading. Therefore, at the present time we cannot confirm this as the afterglow. Details of this source are given below: Source 1: RA (J2000.0): 90.86806 = 06:03:28.33 Dec (J2000.0): -17.08282 = -17:04:58.2 Error: 2.3 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: 0.0240 +/- 0.0038 ct s^-1 Distance: 18 arcsec from Swift/BAT position. Flux: (7.1 +/- 1.1)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/ToO_GRBs/00020775. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21168 SUBJECT: GRB 170524B: Swift-UVOT/XRT Confirmation of Afterglow DATE: 17/05/30 19:07:35 GMT FROM: Jeffrey Gropp at PSU J.D. Gropp (PSU), M.H. Siegel (PSU), J.A. Kennea (PSU), A. Cholden-Brown (PSU) reporting on behalf of the Swift team. The Swift-UVOT and XRT began settled observations of the field of GRB 170524B 120 ks after the BAT trigger (Barthelmy et al., GCN Circ. 21142). A fading source consistent with the XRT position is detected in the UVOT exposures. Swift-XRT performed follow-up observations of the Swift/BAT-detected burst GRB 170524B (Barthelmy et al. GCN Circ.21142), collecting an additional 3ks (5.1 total) of Photon Counting (PC) mode data. One uncatalogued X-ray source has been detected consistent with being within 296 arcsec of the Swift/BAT position. There is also evidence of fading, which is confirmed with UVOT analysis. XRT light curve can be modeled with a power-law decay with a decay index alpha = 1.3 The preliminary UVOT position is: RA (J2000) = 06:03:28.49 = 90.86872 (deg.) Dec (J2000) = -17:04:58.7 = -17.08297 (deg.) with an estimated uncertainty of 0.4 arc sec. (radius, 90% confidence). Preliminary detections 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 120431 126833 1297 19.89+-0.08 white 274703 286595 2027 21.11+-0.23 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.19 in the direction of the burst. The decay inferred from the UVOT white data suggests a slope of approximately -1.3. This circular is an official product of the Swift team.