//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21013 SUBJECT: GRB 170419A: Swift detection of a burst DATE: 17/04/19 13:52:55 GMT FROM: Scott Barthelmy at NASA/GSFC B. Sbarufatti (INAF-OAB/PSU), S. D. Barthelmy (GSFC), A. A. Breeveld (UCL-MSSL), D. N. Burrows (PSU), A. Cholden-Brown (PSU), C. Gronwall (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), M. H. Siegel (PSU) and T. N. Ukwatta (LANL) report on behalf of the Swift Team: At 13:26:40 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170419A (trigger=748898). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 79.866, -21.420 which is RA(J2000) = 05h 19m 28s Dec(J2000) = -21d 25' 12" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak with a duration of about 5 sec. The peak count rate was ~1700 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT settled on the field at 13:28:21.4 UT, 101.2 seconds after the BAT trigger. XRT data were delayed for about 8 minutes until Swift exited the SAA. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 79.8549, -21.4240 which is equivalent to: RA(J2000) = 05h 19m 25.18s Dec(J2000) = -21d 25' 26.4" with an uncertainty of 2.5 arcseconds (radius, 90% containment). This location is 39 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 http://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 3.50 x 10^20 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 591 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.05. Burst Advocate for this burst is B. Sbarufatti (boris.sbarufatti AT brera.inaf.it). 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/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21015 SUBJECT: GRB 170419A: Enhanced Swift-XRT position DATE: 17/04/19 20:39:01 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 2234 s of XRT Photon Counting mode data and 3 UVOT images for GRB 170419A, 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 = 79.85468, -21.42386 which is equivalent to: RA (J2000): 05h 19m 25.12s Dec (J2000): -21d 25' 25.9" with an uncertainty of 1.6 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21018 SUBJECT: GRB 170419A: Swift-BAT refined analysis DATE: 17/04/20 01:00:29 GMT FROM: Amy Lien at GSFC M. Stamatikos (OSU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), B. Sbarufatti (INAF-OAB/PSU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-190 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170419A (trigger #748898) (Sbarufatti et al., GCN Circ. 21013). The BAT ground-calculated position is RA, Dec = 79.854, -21.433 deg which is RA(J2000) = 05h 19m 25.1s Dec(J2000) = -21d 25' 58.0" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 53%. The mask-weighted light curve shows a single-pulse structure that starts and peaks at ~T0. The main emission ends at ~T+3 s, with a tail that lasts till ~T+9 s. T90 (15-350 keV) is 8.18 +- 2.00 sec (estimated error including systematics). The time-averaged spectrum from T-0.39 to T+8.92 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.06 +- 0.26. The fluence in the 15-150 keV band is 3.1 +- 0.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.47 sec in the 15-150 keV band is 1.5 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/748898/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21021 SUBJECT: GRB 170419A: Swift-XRT refined Analysis DATE: 17/04/20 12:12:42 GMT FROM: Phil Evans at U of Leicester V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), B. Mingo (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester) and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team: We have analysed 6.2 ks of XRT data for GRB 170419A, from 550 s to 59.3 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=1.02 (+0.14, -0.12). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.7 (+/-0.3). The best-fitting absorption column is 1.6 (+1.2, -1.0) x 10^21 cm^-2, in excess of the Galactic value of 3.5 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 4.1 x 10^-11 (5.0 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.6 (+1.2, -1.0) x 10^21 cm^-2 Galactic foreground: 3.5 x 10^20 cm^-2 Excess significance: 2.1 sigma Photon index: 1.7 (+/-0.3) If the light curve continues to decay with a power-law decay index of 1.02, the count rate at T+24 hours will be 1.5 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.3 x 10^-14 (7.7 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00748898. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21023 SUBJECT: GRB 170419A: Zadko observatory - Gingin optical observations DATE: 17/04/20 14:00:15 GMT FROM: Alain Klotz at IRAP-CNRS-OMP A. Klotz, D. Turpin (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. Coward (UWA), M. Boer, (UNS-CNRS-OCA), Gendre B. (UVI - Etelman Obs.), A. Williams (PO-UWA), R. Martin (PO-UWA) report: We imaged the field of GRB 170419A detected by SWIFT (trigger 748898) with the Zadko robotic telescope (D=100cm) located at the observatory - Gingin, Australia. The observations started 22.3h after the GRB trigger. The elevation of the field decreased from 49 degrees above horizon and weather conditions were good. We co-added a series of exposures but we did not find any optical transcient in the XRT error box provided by Goad et al. (GCNC 21015): t0+22.3h to t0+22.9h : Rlim = 21.0 Magnitudes were estimated with the nearby NOMAD1 stars and are not corrected for galactic dust extinction. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21031 SUBJECT: GRB 170419A: LCO Observations DATE: 17/04/24 18:49:16 GMT FROM: Antonino Cucchiara at UVI A. Cucchiara, D. Morris (U. of Virgin Islands), C. Guidorzi (U. Ferrara), and B. Gendre (U. of Virgin Islands) report on behalf of a larger collaboration: "On April 19.71 UT (T_0 +3.6h) we began observing the field of GRB 170419A (Sbarufatti et al. GCN #21013) using the Las Cumbres Observatory Global Network 1m Sutherland facility. We obtained a series of observations in R and I bands for a total of 5 minutes on target in each filter. We identified no optical counterpart within the Enhanced Swift-XRT position (Goad et al. GCN #21015) at the following 3-sigma limits: R > 20.9 mag I > 20.8 mag These values are calibrated against nearby USNO-B1 sources and are not corrected for Galactic Extinction." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21035 SUBJECT: GRB 170419A: Swift/UVOT Upper Limits DATE: 17/04/25 17:28:19 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 170419A 592 s after the BAT trigger (Sbarufatti et al., GCN Circ. 21013). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 21015) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 592 742 147 >21.1 white 592 13376 1194 >22.0 v 748 19148 594 >19.6 b 846 7551 313 >20.4 u 822 23245 1108 >21.0 w1 797 7141 313 >20.0 m2 773 6935 274 >19.9 w2 1027 17141 672 >20.7 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998).