//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15071 SUBJECT: GRB 130806A: Swift detection of a burst DATE: 13/08/06 03:08:35 GMT FROM: David Palmer at LANL B.P. Gompertz (U Leicester), D. N. Burrows (PSU), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC), C. J. Mountford (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC) and C. A. Swenson (PSU) report on behalf of the Swift Team: At 02:51:33 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130806A (trigger=565562). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 35.872, +67.530 which is RA(J2000) = 02h 23m 29s Dec(J2000) = +67d 31' 48" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 10 sec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 02:52:40.2 UT, 66.2 seconds after the BAT trigger. Using promptly downlinked data we find a possible X-ray source located at RA, Dec 35.92827, 67.53242 which is equivalent to: RA(J2000) = 02h 23m 42.8s Dec(J2000) = 67d 31' 56.7" with an uncertainty of 9.0 arcseconds (radius, 90% containment). This location is 78 arcseconds from the BAT onboard position, within the BAT error circle. We cannot determine whether the source is fading at the present time. UVOT took a finding chart exposure of 150 seconds with the White filter starting 68 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 1.19. Burst Advocate for this burst is B.P. Gompertz (bpg6 AT le.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/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15072 SUBJECT: GRB 130806A: Enhanced Swift-XRT position DATE: 13/08/06 10:10:23 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 1580 s of XRT Photon Counting mode data and 4 UVOT images for GRB 130806A, 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 = 35.92894, +67.53196 which is equivalent to: RA (J2000): 02h 23m 42.95s Dec (J2000): +67d 31' 55.1" 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15076 SUBJECT: GRB 130806A, Swift-BAT refined analysis DATE: 13/08/06 22:31:21 GMT FROM: Hans Krimm at NASA-GSFC A. Y. Lien (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), B.P. Gompertz (U Leicester), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-61 to T+242 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130806A (trigger #565562) (Gompertz, et al., GCN Circ. 15071). The BAT ground-calculated position is RA, Dec = 35.907, 67.525 deg which is RA(J2000) = 02h 23m 37.7s Dec(J2000) = +67d 31' 30.5" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 95%. The mask-weighted light curves shows a faint initial 2-sec long peak starting at T-5 sec, followed by the main peak from T-1 to T+2 sec. T90 (15-350 keV) is 6.1 +- 0.5 sec (estimated error including systematics). The time-averaged spectrum from T-4.5 to T+2.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.50 +- 0.22. The fluence in the 15-150 keV band is 1.7 +- 0.2 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+0.32 sec in the 15-150 keV band is 1.3 +- 0.1 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/565562/BA/ We note that the fluence ratio in a simple power-law fit between the 25-50 keV band and the 50-100 keV band is 1.41. This fluence ratio is larger than 1.32 which can be achieved in the Band function of alpha=-1.0, beta=-2.5, and Epeak=30 keV. Thus, preliminary analysis shows that Epeak of the burst is very likely around or below 30 keV. Therefore the burst can be classified as an X-ray flash (e.g. Sakamoto et al. 2008, ApJ, 679, 570). A fit to a Band model gives nearly the same reduced chi-squared as a simple power=law fit. The Band fit gives Epeak = 18.9 (+3.2, -5.8) and beta = -2.6 ± 0.3. The alpha parameter is not constrained by the fit. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15077 SUBJECT: GRB 130806A: MITSuME Okayama upper limits DATE: 13/08/07 04:33:15 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of MITSuME collaboration: We observed the field of GRB 130806A (Gompertz et al., GCNC 15071) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2013-08-06 12:29:43 UT (~9.6 h after the burst). We did not find any new point source within the enhanced XRT error circle (Beardmore et al., GCNC 15072) in all the three bands. Three sigma upper limits of the OT are listed below. We used GSC 2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Ic ----------------------------------------------------- 0.54100 15:50:36 4020.0 >19.4 >19.5 >18.7 ----------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15078 SUBJECT: GRB 130806A: Swift-XRT refined Analysis DATE: 13/08/07 05:26:22 GMT FROM: Kim Page at U.of Leicester K.L. Page (U. Leicester) and B.P. Gompertz (U Leicester) report on behalf of the Swift-XRT team: We have analysed 12 ks of XRT data for GRB 130806A (Gompertz et al. GCN Circ. 15071), from 77 s to 57.9 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 15072). The light curve can be modelled with a power-law decay with a decay index of alpha=0.57 (+0.08, -0.09). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.6 (+0.6, -0.5). The best-fitting absorption column is 6.8 (+4.7, -2.9) x 10^21 cm^-2, consistent with the Galactic value of 3.9 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 6.1 x 10^-11 (9.0 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 6.8 (+4.7, -2.9) x 10^21 cm^-2 Galactic foreground: 3.9 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.6 (+0.6, -0.5) If the light curve continues to decay with a power-law decay index of 0.57, the count rate at T+24 hours will be 2.8 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x 10^-13 (2.5 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/00565562. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15079 SUBJECT: GRB 130806A: MITSuME Akeno Optical observation DATE: 13/08/07 06:31:51 GMT FROM: Taketoshi Yoshii at Tokyo Tech T. Yoshii, K. Ito, Y. Saito, Y. Yano, R. Usui, Y. Tachibana, S. Kurita, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 130806A (B.P. Gompertz et al., GCNC 15071) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started on 2013-08-06 14:11:23 UT ( ~11.3 h afterthe burst). And we could not find any new point source within the XRT error circle (A.P. Beardmore et al., GCNC 15072) in all the three bands. The results of photometry (3 sigma upper limits) are listed below. We used GSC2.3 catalog for flux calibration. T0+[hour] MID-UT T-EXP[sec] g' Rc Ic ---------------------------------------------------------------------------------------------------- ~15.0 17:50:01 5580 >21.3 >20.4 >19.7 ---------------------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst [hour] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15084 SUBJECT: GRB 130806A: Swift/UVOT Upper Limits DATE: 13/08/08 14:49:32 GMT FROM: Stephen Holland at STScI S. T. Holland (STScI) and B. P. Gompertz (U Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130806A starting 69 s after the BAT trigger (Gompertz et al. 2013, GCNC 15071). We do not detect any new source consistent with the UVOT-enhanced XRT position (Beardmore et al. 2013, GCNC 15072) in any of the UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the finding chart (FC) exposures and initial summed exposures are presented below. ------------------------------------------------- Filter TSTART TSTOP Exposure Mag ------------------------------------------------- white (FC) 69 218 147 >20.6 u (FC) 282 305 23 >18.2 ------------------------------------------------- b 3571 11,831 1028 >21.3 u 4801 11,172 1082 >21.4 v 4187 5823 393 >19.9 uvw1 4597 10,259 1116 >21.2 uvm2 4391 15,843 1066 >20.9 uvw2 3982 5618 393 >20.7 white 3776 5411 393 >21.8 ------------------------------------------------- The quoted upper limits have not been corrected for the expected extinction due to the Galactic reddening along the line of sight to this burst of E(B-V) = 1.02 mag (Schlafly et al. 2011, ApJS, 737, 103). GRB 130806A was 6 degrees above the Galactic Plane, so this extinction value is highly uncertain.