//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11807 SUBJECT: GRB 110319A: Swift detection of a burst DATE: 11/03/19 02:31:37 GMT FROM: Scott Barthelmy at NASA/GSFC A. Melandri (INAF-OAB), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), P. D'Avanzo (INAF-OAB), J. M. Gelbord (PSU), C. Gronwall (PSU), S. T. Holland (CRESST/USRA/GSFC), N. P. M. Kuin (UCL-MSSL), R. Margutti (INAF-OAB), C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/IASFPA) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 02:16:41 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 110319A (trigger=449578). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 356.401, -66.017 which is RA(J2000) = 23h 45m 36s Dec(J2000) = -66d 01' 01" 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 ~30 sec. The peak count rate was ~3800 counts/sec (15-350 keV), at ~5 sec after the trigger. The XRT began observing the field at 02:17:37.5 UT, 55.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 356.5017, -66.0114 which is equivalent to: RA(J2000) = 23h 46m 0.40s Dec(J2000) = -66d 00' 40.9" with an uncertainty of 2.3 arcseconds (radius, 90% containment). This location is 148 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. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 2.62 x 10^20 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 1.10e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 66 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7' x 2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03. Burst Advocate for this burst is A. Melandri (andrea.melandri 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: 11808 SUBJECT: GRB 110319A: Enhanced Swift-XRT position DATE: 11/03/19 07:59:32 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 285 s of XRT Photon Counting mode data and 1 UVOT images for GRB 110319A, 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 = 356.50181, -66.01113 which is equivalent to: RA (J2000): 23h 46m 0.43s Dec (J2000): -66d 00' 40.1" with an uncertainty of 1.8 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: 11810 SUBJECT: GRB 110319A: Swift-XRT refined Analysis DATE: 11/03/19 13:59:42 GMT FROM: Andrea Melandri at INAF-OAB A. Melandri, B. Sbarufatti and R. Margutti (INAF-OAB) reports on behalf of the Swift-XRT team: We have analysed 9.9 ks of XRT data for GRB 110319A (Melandri et al. GCN Circ. 11807), from 47 s to 23.4 ks after the BAT trigger. The data comprise 33 s in Windowed Timing (WT) mode (the first 7 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 Goad et al. (GCN. Circ 11808). The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=3.7 (+0.6, -0.3). At T+151 s the decay flattens to an alpha of -0.63 (+0.07, -0.65). The light curve breaks again at T+4335 s to a decay with alpha=0.98(+0.11, -0.10). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 3.4 (+0.4, -0.3). The best-fitting absorption column is 2.4 (+0.7, -0.6) x 10^21 cm^-2, in excess of the Galactic value of 2.6 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.33 (+0.13, -0.14) and a best-fitting absorption column of 1.16 (+0.32, -0.18) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (5.0 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.16 (+0.32, -0.18) x 10^21 cm^-2 Galactic foreground: 2.6 x 10^20 cm^-2 Excess significance: 10.8 sigma Photon index: 2.33 (+0.13, -0.14) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00449578. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11811 SUBJECT: GRB 110319A: Swift-BAT refined analysis DATE: 11/03/19 14:28:25 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), A. Melandri (INAF-OAB), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 110319A (trigger #449578) (Melandri, et al., GCN Circ. 11807). The BAT ground-calculated position is RA, Dec = 356.510, -66.008 deg, which is RA(J2000) = 23h 46m 02.4s Dec(J2000) = -66d 00' 28.7" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows two overlapping peaks starting at ~T_zero, peaking at ~T+5 and ~T+13 sec, and ending at ~T+30 sec. T90 (15-350 keV) is 19.3 +- 1.6 sec (estimated error including systematics). The time-averaged spectrum from T-0.3 to T+31.3 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.31 +- 0.43, and Epeak of 21.9 +- 7.0 keV (chi squared 54.2 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.4 +- 0.1 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+13.10 sec in the 15-150 keV band is 2.2 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.55 +- 0.08 (chi squared 86.5 for 57 d.o.f.). 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/449578/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11812 SUBJECT: GRB 110319A: Swift/UVOT Detection DATE: 11/03/19 15:19:16 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU), S. T. Holland (CRESST/USRA/GSFC) and A. Melandri (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 110319A 65s after the BAT trigger (Melandri et al, GCN Circ 11807). We identify an optical afterglow near the enchanced XRT position given by Melandri et al. (GCN Circ. 11810). The transient is only detected in the optical filters and shows fading between the first and second orbits. The preliminary UVOT position is: RA (J2000) 23:46:00.69 = 356.50287 (deg) Dec (J2000) -66:00:40.4 = -66.01122 (deg) with an estimated uncertainty of 0.44 arcsec (radius, 90% confidence, statistical + systematic). Preliminary 3-sigma upper limits and magnitudes using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white (fc) 65 215 147 18.36+-0.07 white 3924 5560 393 20.32+-0.22 v 4336 5971 393 >19.56 b 3719 5355 393 19.51+-0.21 b 11317 11950 615 >20.63 u 277 395 115 18.13+-0.13 u 4950 11310 1081 19.76+-0.18 uvw1 4745 4945 196 >19.72 uvw1 9497 10397 885 >20.58 uvm2 4540 4740 196 >19.64 uvm2 5976 6172 193 >19.69 uvw2 4131 4330 196 >19.91 uvw2 5566 5766 196 >19.91 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).