//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16214 SUBJECT: GRB 140506A: Swift detection of a burst with an optical counterpart DATE: 14/05/06 21:28:16 GMT FROM: David Burrows at PSU/Swift B.P. Gompertz (U Leicester), D. N. Burrows (PSU), S. B. Cenko (GSFC), S. T. Holland (Eureka), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (NASA/GSFC/ORAU), V. Mangano (PSU), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 21:07:36 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 140506A (trigger=598284). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 276.790, -55.562 which is RA(J2000) = 18h 27m 10s Dec(J2000) = -55d 33' 43" 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 ~6500 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 21:09:14.7 UT, 97.9 seconds after the BAT trigger. XRT found a bright, fading, uncatalogued X-ray source located at RA, Dec 276.7752, -55.6353 which is equivalent to: RA(J2000) = +18h 27m 6.05s Dec(J2000) = -55d 38' 07.1" with an uncertainty of 4.7 arcseconds (radius, 90% containment). This location is 265 arcseconds from the BAT onboard position. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 1.01e-08 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 250 seconds with the U filter starting 320 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 18:27:06.03 = 276.77513 DEC(J2000) = -55:38:08.8 = -55.63577 with a 90%-confidence error radius of about 0.63 arc sec. This position is 1.7 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.46 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.09. 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: 16215 SUBJECT: GRB 140506A: Enhanced Swift-XRT position DATE: 14/05/07 04:18:24 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 930 s of XRT Photon Counting mode data and 1 UVOT images for GRB 140506A, 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 = 276.77549, -55.63648 which is equivalent to: RA (J2000): 18h 27m 6.12s Dec (J2000): -55d 38' 11.3" with an uncertainty of 1.4 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: 16216 SUBJECT: GRB 140506A: Swift-XRT refined Analysis DATE: 14/05/07 09:34:53 GMT FROM: Kim Page at U.of Leicester K.L. Page, P.A. Evans and B.P. Gompertz (U Leicester) report on behalf of the Swift-XRT team: We have analysed 7.7 ks of XRT data for GRB 140506A (Gompertz et al. GCN Circ. 16214), from 87 s to 30.4 ks after the BAT trigger. The data comprise 531 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 16215). The late-time light curve (from T0+5.1 ks) can be modelled with a power-law decay with a decay index of alpha=0.91 (+/-0.08). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.65 (+/-0.03). The best-fitting absorption column is 3.14 (+/-0.10) x 10^21 cm^-2, in excess of the Galactic value of 1.1 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.79 (+/-0.09) and a best-fitting absorption column of 2.9 (+/-0.4) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.2 x 10^-11 (5.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.9 (+/-0.4) x 10^21 cm^-2 Galactic foreground: 1.1 x 10^21 cm^-2 Excess significance: 7.6 sigma Photon index: 1.79 (+/-0.09) If the light curve continues to decay with a power-law decay index of 0.91, the count rate at T+24 hours will be 0.058 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.4 x 10^-12 (3.2 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00598284. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16217 SUBJECT: GRB 140506A: VLT/X-shooter spectroscopy DATE: 14/05/07 10:06:33 GMT FROM: Dong Xu at DARK/NBI J. P. U. Fynbo (DARK/NBI), N. R. Tanvir (U. Leicester), P. Jakobsson (U. Iceland), D. Xu, D. Malesani, B. Milvang-Jensen (DARK/NBI) report on behalf of the X-shooter GRB collaboration: We observed the optical afterglow of GRB 140506A (Gompertz et al., GCN 16214) with the VLT/X-shooter spectrograph, equipped with the UVB/VIS/NIR arms and covering the wavelength range 3000-25000 AA. From the first acquisition image at May 7.21 UT, the afterglow has m(R)=20.9 +/- 0.2 mag against the USNO-B1 (R2) catalog. The spectra (8 x 600 s) started at May 7.21 UT and ended May 7.28 UT, and the mean time is May 7.24 UT (8.77 hr after the GRB). We detect absorption features in the UVB/VIS arms, interpreted as due to Mg II 2796, 2803, He I 3889, and Ca II H+K, at a common redshift of z = 0.889, which is treated as the tentative redshift of the GRB's host galaxy. The combined spectrum is very red with very weak signal in the UVB arm, possibly due to the large host extinction. We acknowledge excellent support from the observing staff at Paranal, in particular Valentin D. Ivanov and Yazan Momany. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16218 SUBJECT: GRB 140506A: Swift-BAT refined analysis DATE: 14/05/07 11:50:34 GMT FROM: Scott Barthelmy at NASA/GSFC C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), B.P. Gompertz (U Leicester), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from recent telemetry downlinks, we report further analysis of BAT GRB 140506A (trigger #598284) (Gompertz, et al., GCN Circ. 16214). The BAT ground-calculated position is RA, Dec = 276.806, -55.556 deg, which is RA(J2000) = 18h 27m 13.5s Dec(J2000) = -55d 33' 20.2" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 11%. The mask-weighted light curve a bright initial pulse strting at ~T-5 sec, peaking at ~T+0.2 sec, and returning to baseline at ~T+5 sec. Then there were two weaker peaks at ~T+60 sec and at ~T+110 sec. T90 (15-350 keV) is 111.1 +- 9.6 sec (estimated error including systematics). The time-averaged spectrum from T-0.20 to T+120.18 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.68 +- 0.16. The fluence in the 15-150 keV band is 2.8 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.00 sec in the 15-150 keV band is 10.9 +- 0.9 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/598284/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16219 SUBJECT: GRB 140506A: Swift/UVOT Detection DATE: 14/05/07 17:00:49 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) 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 140506A 108 s after the BAT trigger (Gompertz et al., GCN Circ. 16214). A source consistent with the XRT position (Osborne et al. GCN Circ. 16215) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 18:27:06.04 = 276.77516 (deg.) Dec (J2000) = -55:38:08.7 = -55.63575 (deg.) with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first and second orbits are: Filter T_start(s) T_stop(s) Exp(s) Mag white (fc) 108 257 147 17.19+-0.03 white 108 1545 390 17.82+-0.05 white 6078 6278 196 20.07+-0.14 white 11748 12655 885 21.52+-0.26 v 650 1576 98 >18.87 v 5053 6688 393 19.82+-0.32 b 576 1520 97 19.40+-0.30 b 5873 7334 221 >20.57 u (fc) 320 570 245 17.34+-0.07 u 320 1496 323 17.50+-0.07 u 5668 7303 393 20.04+-0.34 uvw1 700 1471 77 18.60+-0.29 uvw1 5463 7098 393 >20.29 uvm2 675 1446 97 >18.96 uvm2 5257 6893 393 >20.17 uvw2 626 1570 116 >19.41 uvw2 6284 6484 196 >19.97 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.09 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16220 SUBJECT: GRB 140506A: Fermi GBM Detection DATE: 14/05/07 17:22:01 GMT FROM: Peter Jenke at MSFC P. Jenke (UAH) reports on behalf of the Fermi GBM Team: "At 21:07:36.88 UT on May 6 2014, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 140506A (trigger 421103259/140506880), which was also detected by Swift (B.P. Gompertz et al. 2014, GCN 16214). The GBM on-ground location, using the Fermi GBM trigger data, is consistent with the Swift/XRT location. The angle of the burst direction to the Fermi LAT boresight is 135 degrees. The GBM light curve consists of one main peak near T0 and a late, smaller peak at ~T0+60 s with a duration (T90) of about 64 s (50-300 keV). The time-averaged spectrum from T0-1.9 s to T0+2.2s is well fit by a Band function with an Epeak of 141 +/- 36 keV, alpha = -0.9 +/- 0.2 and beta = -2.0 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (3.5 +/- 0.2)E-06 erg/cm^2. The 1.0-sec peak photon flux measured starting from T0 in the 10-1000 keV band is 14.2 +/- 0.7 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: 16223 SUBJECT: Konus-Wind observation of GRB 140506A DATE: 14/05/08 13:33:01 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lyssenko, and T. Cline on behalf of the Konus-Wind team, report: A long-duration GRB 140506A (Swift-BAT trigger 598284: Gompertz et al., GCN 16214; Markwardt et al., GCN 16218; Fermi-GBM detection: Jenke, GCN 16220) triggered Konus-Wind at T0=76059.098 s UT (21:07:39.098). The light curve shows two bursting episodes: a narrow, double-peaked pulse from ~T0-1.1 s to ~T0+1.6 s, followed by a broad, weak, soft pulse from ~T0+49 s to ~T0+63 s A total duration of the burst is ~64 s. The emission is seen up to ~7 MeV. As observed by Konus-Wind, the burst had a fluence of 6.6(-1.6,+1.8)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+0.640 s, of 6.2(-1.9,+2.5)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the first bursting episode (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 18 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.3 (-0.2,+0.3), the high energy photon index beta = -2.3 (-7.7,+0.4), the peak energy Ep = 187 (-59,+90) keV, chi2 = 94/97 dof. The time-averaged spectrum of the second bursting episode (measured from T0+49.408 to T0+65.792 s) is best fit in the 20 keV - 18 MeV range by a simple power-law function with the photon index 2.06(-0.13,+0.14), chi2 = 98/98 dof. Assuming the redshift z=0.889 (Fynbo et al., GCN 16217) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, and Omega_Lambda = 0.73, we estimate the following rest-frame parameters: the isotropic energy release E_iso is ~1.4x10^52 erg, the peak luminosity L_iso is ~2.5x10^52 erg/s, and the rest-frame peak energy, Ep,i, is ~350 keV (as derived from the spectrum of the first episode). The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB140506_T76059/ All the quoted errors are at the 1 sigma confidence level. All the quoted values are preliminary.