//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11782 SUBJECT: GRB 110312A: Swift detection of a burst DATE: 11/03/12 18:14:48 GMT FROM: Scott Barthelmy at NASA/GSFC S. R. Oates (UCL-MSSL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC), R. L. C. Starling (U Leicester), E. Troja (NASA/GSFC/ORAU) and T. N. Ukwatta (MSU) report on behalf of the Swift Team: At 17:55:37 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 110312A (trigger=449074). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 157.479, -5.255 which is RA(J2000) = 10h 29m 55s Dec(J2000) = -05d 15' 18" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is typical for image triggers, the BAT lightcurve does not show anything significant. The XRT began observing the field at 17:58:16.3 UT, 159.1 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 157.4813, -5.2628 which is equivalent to: RA(J2000) = 10h 29m 55.50s Dec(J2000) = -05d 15' 46.0" with an uncertainty of 2.3 arcseconds (radius, 90% containment). This location is 28 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 3.72 x 10^20 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 4.19e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 167 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 0.04. Burst Advocate for this burst is S. R. Oates (sro AT mssl.ucl.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: 11783 SUBJECT: GRB 110312A: Swift-BAT refined analysis DATE: 11/03/12 22:36:48 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), S. R. Oates (UCL-MSSL), 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-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 110312A (trigger #449074) (Oates, et al., GCN Circ. 11782). The BAT ground-calculated position is RA, Dec = 157.500, -5.259 deg, which is RA(J2000) = 10h 30m 00.0s Dec(J2000) = -05d 15' 32.6" with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 26%. The mask-weighted light curve shows a single start at ~T+25 sec, peaking around T+45 sec, and ending at ~T+65 sec. T90 (15-350 keV) is 28.7 +- 7.6 sec (estimated error including systematics). The time-averaged spectrum from T+24.1 to T+64.9 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.32 +- 0.26. The fluence in the 15-150 keV band is 8.2 +- 1.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+44.08 sec in the 15-150 keV band is 1.2 +- 0.3 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/449074/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11784 SUBJECT: GRB 110312A: Enhanced Swift-XRT position DATE: 11/03/13 00:21:43 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 1937 s of XRT Photon Counting mode data and 3 UVOT images for GRB 110312A, 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 = 157.48111, -5.26262 which is equivalent to: RA (J2000): 10h 29m 55.47s Dec (J2000): -05d 15' 45.4" with an uncertainty of 1.7 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: 11785 SUBJECT: GRB 110312A: GROND Upper Limits DATE: 11/03/13 08:10:50 GMT FROM: Ana Nicuesa at TLS Tautenburg A. Nicuesa Guelbenzu (TLS Tautenburg), F. Olivares E., and J. Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 110312A (Swift trigger 449074; Oates et al., GCN #11782) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La Silla Observatory (Chile). Observations started at 23:57 UT on March 11, 2011, 6 hours after the GRB trigger, and continued for 2.6 hours. They were performed at an average seeing of 1.3" and at an average airmass of 1.5. We find no sources within the the 1.7" enhanced XRT error circle (Osborne et al.; GCN #11783). Co-added images of 64.5 min of integration time in g'r'i'z' and 56 min in JHK yield the following 3-sigma upper limits (all in the AB system): g' > 24.3, r' > 24.1, i' > 23.0, z' > 23.1, J > 22.0, H > 21.4, and K > 19.3 calibrated against GROND zeropoints and 2MASS field stars. No corrections for the expected Galactic foreground extinction were made, which correspond to a reddening of E(B-V)=0.04 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11786 SUBJECT: GRB 110312A: Swift-XRT refined Analysis DATE: 11/03/13 09:11:06 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) and S. R. Oates (UCL-MSSL) report on behalf of the Swift-XRT team: We have analysed 2.9 ks of XRT data for GRB 110312A (Oates et al. GCN Circ. 11782), from 147 s to 18.1 ks after the BAT trigger. The data comprise 82 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 11784). The light curve can be modelled with an initial power-law decay with an index of alpha=3.8 (+0.8, -1.1), followed by a break at T+356 s to an alpha of 0.55 (+0.10, -0.12). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.36 (+0.22, -0.21). The best-fitting absorption column is 4.3 (+/-0.8) x 10^21 cm^-2, in excess of the Galactic value of 3.7 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (8.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 4.3 (+/-0.8) x 10^21 cm^-2 Galactic foreground: 3.7 x 10^20 cm^-2 Excess significance: 9.5 sigma Photon index: 2.36 (+0.22, -0.21) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00449074. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11787 SUBJECT: GRB 110312A: Swift/UVOT Upper Limits DATE: 11/03/13 13:26:40 GMT FROM: Samantha Oates at MSSL S. R Oates (UCL-MSSL) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 110312A 168 s after the BAT trigger (Oates et al., GCN Circ. 11782). No optical afterglow consistent with the XRT position (Evans et al., GCN Circ. 11784) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag ---------------------------------------------------------------- white_FC 168 318 147 >21.8 u_FC 327 577 246 >20.1 white 168 1896 429 >21.3 v 657 1946 156 >19.2 b 582 6063 315 >20.6 u 327 2020 382 >20.1 w1 706 1995 136 >19.6 m2 682 1970 156 >19.6 w2 1036 1402 39 >18.8 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11788 SUBJECT: GRB 110312A: RTT150 optical observations DATE: 11/03/13 15:32:35 GMT FROM: Rodion Burenin at IKI, Moscow I. Bikmaev, R. Zhuchkov, R. Gumerov, A. Nemtinov, N. Sakhibullin (Kazan University), R. Burenin, M. Pavlinsky, R. Sunyaev (IKI), Z. Eker, I. Khamitov (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.) report: The field of GRB 110312A (Oates et al., GCN 11782) was observed with Russian-Turkish 1.5-m telescope (RTT150,Bakirlitepe, TUBITAK National Observatory, Turkey) in March 12, 2011, during UT 20:00 - 21:40, i.e. starting approximately 2 hours after the burst. We obtained serie of 16 exposures by 300 sec each in Rc filter. We found no optical source within the 1.7" enhanced XRT error circle (Osborne et al.; GCN 11784) in co-added image with frame limit of Rc ~ 23.5 mag //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11789 SUBJECT: GRB110312A: MITSuME Okayama Optical upper limits DATE: 11/03/14 08:41:28 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 the MITSuME collaboration: We observed the field of GRB 110312A (Oates et al., GCN 11782) 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 2011-03-12 18:35:03 UT (~39 mins after the burst). We did not find any new point source within the enhanced XRT circle (Osborne et al., GCNC 11784) in all the three bands. Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration. T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 0.02269 18:28:18 1020.0 >17.8 >18.0 >17.4 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]