//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19716 SUBJECT: GRB 160716A: Swift detection of a burst DATE: 16/07/16 01:20:39 GMT FROM: David Palmer at LANL L. M. Z. Hagen (PSU), S. D. Barthelmy (GSFC), J. A. Kennea (PSU) and D. M. Palmer (LANL) report on behalf of the Swift Team: At 01:08:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 160716A (trigger=704572). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 190.544, -61.366 which is RA(J2000) = 12h 42m 10s Dec(J2000) = -61d 21' 56" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a copmplex structure with a duration of about 10 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 01:09:55.7 UT, 85.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 190.43632, -61.35080 which is equivalent to: RA(J2000) = 12h 41m 44.72s Dec(J2000) = -61d 21' 02.9" with an uncertainty of 4.0 arcseconds (radius, 90% containment). This location is 193 arcseconds from the BAT onboard position, outside 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 9.61 x 10^21 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 88 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 none of the XRT error circle. 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 large, but uncertain extinction expected. Burst Advocate for this burst is L. M. Z. Hagen (lea.zernow.hagen AT gmail.com). 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: 19717 SUBJECT: GRB 160716A: Enhanced Swift-XRT position DATE: 16/07/16 09:15:26 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 666 s of XRT Photon Counting mode data and 1 UVOT images for GRB 160716A, 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 = 190.43749, -61.35098 which is equivalent to: RA (J2000): 12h 41m 45.00s Dec (J2000): -61d 21' 03.5" with an uncertainty of 2.1 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: 19718 SUBJECT: GRB 160716A: Swift-XRT refined Analysis DATE: 16/07/16 13:23:48 GMT FROM: Phil Evans at U of Leicester K.L. Page (U. Leicester), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), T.G.R. Roegiers (PSU), B. Mingo (U. Leicester), A.P. Beardmore (U. Leicester) and L.M.Z. Hagen report on behalf of the Swift-XRT team: We have analysed 6.7 ks of XRT data for GRB 160716A (Hagen et al. GCN Circ. 19716), from 98 s to 24.2 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 19717). The light curve can be modelled with a power-law decay with a decay index of alpha=0.87 (+0.15, -0.13). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.1 (+1.0, -0.8). The best-fitting absorption column is 2.7 (+1.9, -1.4) x 10^22 cm^-2, in excess of the Galactic value of 9.6 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 6.5 x 10^-11 (1.7 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.7 (+1.9, -1.4) x 10^22 cm^-2 Galactic foreground: 9.6 x 10^21 cm^-2 Excess significance: 2.1 sigma Photon index: 2.1 (+1.0, -0.8) If the light curve continues to decay with a power-law decay index of 0.87, the count rate at T+24 hours will be 7.3 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.8 x 10^-14 (1.2 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00704572. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19719 SUBJECT: GRB 160716A: Swift-BAT refined analysis DATE: 16/07/16 14:36:32 GMT FROM: Scott Barthelmy at NASA/GSFC T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), L. M. Z. Hagen (PSU), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+877 sec from the recent telemetry downlinks, we report further analysis of BAT GRB 160716A (trigger #704572) (Hagen, et al., GCN Circ. 19716). The BAT ground-calculated position is RA, Dec = 190.502, -61.364 deg, which is RA(J2000) = 12h 42m 00.6s Dec(J2000) = -61d 21' 51.8" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 75%. The mask-weighted light curve shows at least 2 overlapping peaks starting at ~T-5sec, peaking at ~T+1 sec, and ending at ~T+20 sec. T90 (15-350 keV) is 6.39 +- 0.57 sec (estimated error including systematics). The time-averaged spectrum from T-0.43 to T+6.73 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.29 +- 0.30. The fluence in the 15-150 keV band is 1.8 +- 0.3 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+0.95 sec in the 15-150 keV band is 0.8 +- 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/704572/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19721 SUBJECT: GRB 160716A: Swift/UVOT Detection DATE: 16/07/18 00:25:59 GMT FROM: Lea Hagen at PSU L. M. Z. Hagen (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160716A 88 s after the BAT trigger (Hagen et al., GCN Circ. 19716). A source consistent with the XRT position (Evans et al., GCN Circ. 19717) is detected in the initial UVOT exposures in the white filter. The source has marginal evidence for fading but is not seen in the Digitized Sky Survey (DSS), so it is unclear at this time whether it is the optical afterglow. 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 88 773 183 19.93+-0.23 white 6218 6418 196 20.47+-0.35 white 24012 98905 490 20.62+-0.25 v 631 651 19 >17.58 b 556 750 38 >18.95 u 301 725 265 >19.63 uvw1 681 701 19 >17.48 uvm2 656 676 19 >17.10 uvw2 607 627 19 >17.52 The magnitudes in the table are not corrected for the Galactic extinction due to the large, but uncertain, reddening of E(B-V) = 1.47 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19742 SUBJECT: GRB 160716A: TAROT La Silla observatory optical observations DATE: 16/07/29 21:58:47 GMT FROM: Alain Klotz at IRAP-CNRS-OMP Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP), Boer, M., Laugier, R. (CNRS-ARTEMIS), Gendre B. (UVI - Etelman Obs.) report: We imaged the field of GRB 160716A detected by SWIFT (trigger 704572) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile. The observations started 43.6s after the GRB trigger (15.6s after the notice). The elevation of the field decreased from 44 degrees above horizon and weather conditions were good. The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). In the error box of XRT provided by Evans et al. (GCNC 19717) we do not detect any OT with a limiting magnitude of: t0+43.6s to t0+103.6s : Rlim = 16.7 The second image is 30.0s exposure in tracking mode: t0+117.4s to t0+147.4s : Rlim = 17.5 We co-added a series of exposures: t0+117.4s to t0+412.5s : Rlim = 18.2 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon=301.8222 lat= +1.4859 and the galactic extinction in R band is about magnitudes.