//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22618 SUBJECT: GRB 180409A: Tiled Swift observations DATE: 18/04/09 23:09:15 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a series of observations, tiled on the sky, of the IPN GRB 180409A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00069 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the IPN event is high: 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: 22619 SUBJECT: IPN Triangulation of GRB 180409A DATE: 18/04/10 05:36:22 GMT FROM: Anna Kozlova at Ioffe Institute K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, D.Svinkin, and T. Cline on behalf of the Konus-Wind team, V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa, and A. Goldstein, on behalf of the Fermi GBM team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report: A long-duration GRB 180409A was detected by Fermi (GBM), Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), and Swift (BAT) at about 29899 s UT (08:18:19). 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: 175.842 (11h 43m 22s) +36.308 (+36d 18' 30") Corners: 175.961 (11h 43m 51s) +35.973 (+35d 58' 21") 176.118 (11h 44m 28s) +36.645 (+36d 38' 43") 175.721 (11h 42m 53s) +36.644 (+36d 38' 37") 175.567 (11h 42m 16s) +35.969 (+35d 58' 10") --------------------------------------------- The error box area is 772 sq. arcmin, and its maximum dimension is 49 arcmin (the minimum one is 19 arcmin). The Sun distance was 131 deg. This box may be improved. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB180409_T29904/IPN/ Swift ToO has been approved (Evans, GCN Circ. 22618). The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22621 SUBJECT: Konus-Wind observation of GRB 180409A DATE: 18/04/10 10:00:09 GMT FROM: Dmitry Frederiks at Ioffe Institute D. Frederiks, S. Golenetskii, R.Aptekar, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report: The long GRB 180409A (IPN Triangulation: Hurley et al., GCN 22619) triggered Konus-Wind at T0=29904.770 s UT (08:18:24.770) The burst light curve shows a multi-peaked structure, which started at ~T0-3 s and peaked at ~T0+9.4 s. The total duration of the burst is ~20 s. The emission is seen up to ~3 MeV. As observed by Konus-Wind, the burst had a fluence of (8.8 ± 1.3)x10^-6 erg/cm2 and a 64-ms peak energy flux, measured from T0+9.408, of (9.9 ± 1.5)x10^-6 erg/cm2 (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum (measured from T0 to T0+17.920 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.96 (-0.09,+0.10), the high energy photon index beta = -3.1 (-6.9,+0.42), the peak energy Ep = 180 (-14,+15) keV, chi2 = 67/97 dof. The spectrum near the peak count rate (measured from T0+7.936 to T0+9.728 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.50 (-0.13,+0.20), the high energy photon index beta = -3.5 (-6.5,+0.8), the peak energy Ep = 266 (-35,+26) keV, chi2 = 81/78 dof. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180409_T29904/ All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22625 SUBJECT: GRB 180409A: Swift-XRT observations DATE: 18/04/10 14:35:14 GMT FROM: Aaron Tohuvavohu at PSU/Swift A. Tohuvavohu (PSU), S. J. LaPorte (PSU), A.P. Beardmore (U. Leicester), S.L. Gibson (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the IPN-detected burst GRB 180409A in a series of observations tiled on the sky. The total exposure time is 3.5 ks, distributed over 4 tiles; the maximum exposure at a single sky location was 2.4 ks. The data were collected between T0+53.5 ks and T0+71.6 ks, and are entirely in Photon Counting (PC) mode. One uncatalogued X-ray source has been detected, 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): 175.8434 = 11:43:22.42 Dec (J2000.0): +36.2335 = +36:14:00.6 Error: 3.6 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: 0.0258 +/- 0.0068 ct s^-1 Distance: 268 arcsec from IPN position. Flux: (8.3 +/- 2.2)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00069. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22626 SUBJECT: GRB 180409A: Fermi GBM observation DATE: 18/04/10 18:11:51 GMT FROM: Elisabetta Bissaldi at INFN,Bari E. Bissaldi (Politecnico & INFN Bari) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 08:18:18.67 UT on 9 April 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180409A (trigger 544954703 / 180409346), which was triangulated by IPN (Hurley et al., GCN 22619) and was also detected by Konus (Frederiks et al., GCN 22621). The on-ground calculated location, using the GBM trigger data, is RA = 178.18, DEC = +36.050 (J2000 degrees), with an uncertainty of 1 degree (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ). The angle from the Fermi LAT boresight at the GBM trigger time is 71 degrees. The GBM light curve consists of multiple peaks with a duration (T90) of about 13 s (50-300 keV). The time-averaged spectrum from T0-0.5 s to T0+15 s is best fit by a Band function with Epeak = 151 +/- 5 keV, alpha = -0.85 +/- 0.03, and beta = -2.33 +/- 0.05. The event fluence (10-1000 keV) in this time interval is (2.87 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+10.1 s in the 10-1000 keV band is 41 +/- 1 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22635 SUBJECT: GRB 180409A CALET Gamma-Ray Burst Monitor detection DATE: 18/04/12 05:09:52 GMT FROM: Takanori Sakamoto at AGU A. Yoshida, T. Sakamoto, V. Pal'shin, Y. Kawakubo, A. Tezuka, S. Matsukawa, H. Onozawa (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena) and the CALET collaboration: The long GRB 180409A (IPN triangulation: Hurley et al., GCN circ. 22619; Konus-Wind detection: Frederiks et al., GCN circ. 22621; Fermi-GBM detection: Bissaldi and Meegan GCN circ. 22626) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 08:18:17.669 UTC on 9 April 2018. The burst signal was seen by all CGBM detectors. The burst light curve shows several partially overlapped short pulses which start at T+3.0 sec, peaks at T+12.3 sec and ends at T+14.9 sec. The T90 and the T50 durations measured by the SGM data are 10.6 +- 0.7 sec and 5.9 +- 1.8 sec (40-1000 keV), respectively. The ground processed light curve is available at http://cgbm.calet.jp/cgbm_trigger/ground/1207297067/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22643 SUBJECT: GRB 180409A: Swift-XRT afterglow detection DATE: 18/04/15 03:23:31 GMT FROM: Aaron Tohuvavohu at PSU/Swift A. Tohuvavohu (PSU), S. J. LaPorte (PSU), A.P. Beardmore (U. Leicester), S.L. Gibson (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has conducted further observations of the field of the IPN-detected burst GRB 180409A (Yoshida et al. GCN Circ. 22635). The observations now extend from T0+53.4 ks to T0+455.1 ks. The source previously reported by Tohuvavohu et al. (GCN Circ. 22625), "Source 1", is fading with 3-sigma significance, and is therefore likely the GRB afterglow. Using 1887 s of PC mode data and 2 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 = 175.84306, +36.23354 which is equivalent to: RA (J2000): 11h 43m 22.33s Dec(J2000): +36d 14' 00.8" with an uncertainty of 3.1 arcsec (radius, 90% confidence). This position is 4.5 arcmin from the IPN position. The light curve can be modelled with a power-law decay with a decay index of alpha=1.0 (+/-0.3). The results of the XRT-team automatic analysis of the likely afterglow are at http://www.swift.ac.uk/xrt_products/TILED_GRB00069/Source1.php. The results of the full analysis of the tiled XRT observations are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00069. This circular is an official product of the Swift-XRT team.