//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12335 SUBJECT: GRB 110915A: Swift detection of a burst DATE: 11/09/15 13:29:30 GMT FROM: Scott Barthelmy at NASA/GSFC S. T. Holland (CRESST/USRA/GSFC), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), S. Campana (INAF-OAB), J. R. Cummings (NASA/UMBC), P. D'Avanzo (INAF-OAB), P. A. Evans (U Leicester), C. Gronwall (PSU), E. A. Hoversten (PSU), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), P. T. O'Brien (U Leicester), P. Romano (INAF-IASFPA), B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU), C. A. Swenson (PSU) and G. Tagliaferri (INAF-OAB) report on behalf of the Swift Team: At 13:20:44 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 110915A (trigger=503219). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 310.851, -0.709 which is RA(J2000) = 20h 43m 24s Dec(J2000) = -00d 42' 33" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows multiple peaks with a total duration of about 95 sec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~68 sec after the trigger. The XRT began observing the field at 13:22:00.5 UT, 76.1 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 310.8242, -0.7231 which is equivalent to: RA(J2000) = 20h 43m 17.80s Dec(J2000) = -00d 43' 23.1" with an uncertainty of 4.7 arcseconds (radius, 90% containment). This location is 108 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. UVOT took a finding chart exposure of 150 seconds with the White filter starting 84 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 0.06. Burst Advocate for this burst is S. T. Holland (Stephen.T.Holland AT nasa.gov). 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: 12336 SUBJECT: GRB 110915A: Prompt enhanced Swift-XRT position DATE: 11/09/15 14:10:25 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Using promptly downlinked XRT event data for GRB 110915A, we find an enhanced XRT position of the afterglow: RA, Dec: 310.8242, -0.7241 which is equivalent to: RA (J2000) = 20 43 17.81 Dec (J2000) = -00 43 26.7 with an uncertainty of 3.4 arc sec (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/503219. Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12337 SUBJECT: GRB 110915A: MASTER-Net early limit DATE: 11/09/15 16:30:29 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Yurkov, Yu.Sergienko, E.Sinyakov, D.Varda, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev,E.Konstantinov, Irkutsk State University E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Sankovich Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov Ural State University, Kourovka MASTER robotic telescope (MASTER-Net: http://observ.pereplet.ru) located at Blagoveschensk (Amur-site) was pointed to the GRB110915A 15 sec after notice time and 31 sec after GRB time at 2011-09-15 13:21:15 UT. On our first (10s exposure) MASTER II telescope set we haven`t found optical transient within SWIFT error-box (Holland et al., GCN Circ 12335). Unfortunatelly the main telescopes was not in focus. On our first (5s exposure) MASTER VWF (Very Wide Field Camera - FOV=420 square degrees) set we haven`t found optical transient within SWIFT error-box (Holland et al., GCN Circ 12335). Date T_start-T_trig ExpTime Limit Coadd Instrum (UT) (s) (s) (unfilt) 13:21:15 31 10 12 No MASTER II 13:21:17 33 5 12 No MASTER VWF 13:21:17 33 60 14 12 MASTER VWF The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12338 SUBJECT: GRB 110915A: MITSuME Akeno Optical upper limits DATE: 11/09/15 16:32:13 GMT FROM: Yoichi Yatsu at Tokyo Tech. K. Kawakami, K. Tokoyoda, Y. Yatsu, Y. Aoki, M. Hayashi, S. Song, R. Usui, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed GRB 110915A (S. T. Holland et al, GCN12335) with the optical three color (g, Rc, and Ic) CCD camera attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The follow-up observation was started at 14:29:30, ~69 min after the BAT trigger. We did not find any new point source within the enhanced XRT error circle (P.A. Evans et al., GCNC 12336) in two bands. Photometric results and are listed below. We used GSC2.3 catalog for flux calibration. T0+[s] MID-UT T-EXP[sec] g' Rc Ic --------------------------------------------------------------------------------- +4126 14:34:59 1440 --- >17.6 >17.6 --------------------------------------------------------------------------------- T0+ : Elapsed time after the burst [sec] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12339 SUBJECT: GRB 110915A: GMG optical upper limit DATE: 11/09/15 17:05:38 GMT FROM: Dong Xu at Weizmann Inst X.-H. Zhao (YNAO), D. Xu (WIS), J.-R. Mao & J.-M. Bai (YNAO) report on a larger collaboration: We observed the XRT field (Evans, GCN 12336) of GRB 110915A (Holland et al., GCN 12335) with the 2.4m GMG telescope in Yunnan, China equipped with YFOSC. Observations started at 13:58:09 UT, 15th Sep. 2011 (i.e., 0.6236 hr after the burst), and 1x20 min R-band and 1x20 min V-band images were obtained under the cloudy weather. No optical source was present within the XRT error circle in GCN #12336, which sets a 3\sigma upper limit of R~21.6 mag, calibrated with the USNO B1 catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12340 SUBJECT: GRB 110915A: Enhanced Swift-XRT position DATE: 11/09/15 19:22:20 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 2062 s of XRT Photon Counting mode data and 4 UVOT images for GRB 110915A, 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 = 310.82447, -0.72312 which is equivalent to: RA (J2000): 20h 43m 17.87s Dec (J2000): -00d 43' 23.2" with an uncertainty of 1.6 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: 12341 SUBJECT: GRB 110915B: SuperAGILE localization of a long GRB DATE: 11/09/15 21:29:14 GMT FROM: Marco Feroci at IASF/INAF E. Del Monte, I. Donnarumma, Y. Evangelista, M. Feroci, F. Lazzarotto, L. Pacciani, P. Soffitta, E. Costa, I. Lapshov, M. Rapisarda (INAF/IASF Rome), G. Barbiellini, F. Longo, E. Moretti (INFN Trieste), A. Bulgarelli, F. Gianotti, M. Trifoglio, G. Di Cocco, C. Labanti, F. Fuschino, M. Marisaldi, M. Galli (INAF/IASF Bologna), A. Giuliani, A. Chen, S. Mereghetti, F. Perotti, P. Caraveo (INAF/IASF Milan), M. Tavani, M. Cardillo, G. Pucella, V. Vittorini, A. Argan, A. Trois, G. Piano, S. Sabatini (INAF/IASF Rome), A. Pellizzoni, M. Pilia (INAF/OA Cagliari), S. Vercellone, F. D'Ammando (INAF/IASF Palermo), P. W. Cattaneo, A. Rappoldi (INFN Pavia), P. Picozza, A. Morselli, E. Striani, (INFN Roma-2), M. Prest, E. Vallazza (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), P. Giommi, C. Pittori, F. Lucarelli, P. Santolamazza, F. Verrecchia (ASDC) and L. Salotti (ASI), on behalf of the AGILE Team, report: "SuperAGILE detected a gamma ray burst on 15 September 2011, at 18:24:19 UT. The event had a duration of about 18 s in the 20-60 keV energy range, with a single peak structure. Assuming a crab-like energy spectrum, the peak flux on 1-s timescale was 7.73E-08 erg/cm2/s. The burst position was reconstructed as (RA, Dec) (77.548, 1.925) deg, which is: RA(J2000) = 05h 10m 11.57s Dec(J2000) = 1d 55' 30.98" with an uncertainty of 4' radius. The given uncertainty accounts for both the statistical and systematic errors. An analysis of the AGILE Gamma Ray Imager (GRID) data is in progress." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12342 SUBJECT: GRB 110915A: 1.23m CAHA I-band observations DATE: 11/09/15 22:54:19 GMT FROM: Javier Gorosabel at IAA-CSIC R. Sanchez-Ramirez (IAA-CSIC), N. Morales (IAA-CSIC), J. Gorosabel (IAA-CSIC), J.L. Ortiz (IAA-CSIC), P. Kubanek (U. Valencia & IAA-CSIC), A. de Ugarte Postigo (DARK/NBI), A.J. Castro-Tirado (IAA-CSIC), report on behalf of a larger collaboration: "We imaged the field of the Swift GRB 110915A (Holland et al., GCN Circ 12335) with the 1.23m Calar Alto telescope. The observations were carried out in the I-band on Sep 15.7984-15.8500 UT (starting 5.81 hours after the GRB) with a total exposure time of 25 X 180 = 4500s. No object brighter than I=21.5 is detected in the XRT error circle (Evans et al., GCN Circ 12340)." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12343 SUBJECT: GRB 110915A: NOT observations DATE: 11/09/16 00:26:36 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK, NBI), P. Jakobsson (U. Iceland), A. de Ugarte Postigo (DARK, NBI), J. Lykke (NOT), D. Xu (WIS), and N. R. Tanvir (U. Leicester) report on behalf of a larger collaboration: Using ALFOSC on the Nordic Optical Telescope (NOT) we have obtained R-band (3 x 600 s) and z-band (18 x 300 s) imaging of the GRB 110915A field (Holland et al., GCN 12335) starting on 2011 September 15.87 UT (around 7.5 hr after the burst). We do not detect any object within the refined XRT error circle (Evans et al., GCN 12340). The limiting magnitudes are R(Vega) = 24.3 and z(AB) = 23.5, calibrated against the USNO-B1 and SDSS catalogs, respectively. Using our R-band limit and preliminary X-ray fluxes, we obtain a corresponding upper limit on beta_OX of around 0.1, rendering the burst dark according to the definition proposed by Jakobsson et al. (2004, ApJ, 617, L21). This burst may therefore be at high redshift, or suffer from significant dust extinction. The presence of significant excess absorption in the X-ray afterglow spectrum (http://www.swift.ac.uk/xrt_spectra/00503219/) makes the second option more likely. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12344 SUBJECT: GRB 110915A: MITSuME Okayama and Ishigakijima Optical upper limits DATE: 11/09/16 00:58:08 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, (OAO, NAOJ), H. Hanayama (IAO, NAOJ), K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), T. Miyaji J. Watanabe, (IAO, 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 110915A (Holland et al., GCNC 12335) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory and the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. We did not find any new point source within the enhanced XRT error circle (Evans, GCNC 12336) in all the three bands. Three sigma upper limits of the OT are listed below. We used SDSS catalog for flux calibration. Ishigakijima Astronomical Observatory: The observation started on 2011-09-15 13:28:55 UT (~8.2 min after the burst). T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 0.07421 15:07:35 9360.0 >22.0 >21.8 >20.7 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] Okayama Astrophysical Observatory: The observation started on 2011-09-15 14:58:17 UT (~1.6 h after the burst). T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 0.08645 15:25:12 3060.0 >19.8 >20.2 >19.34 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12345 SUBJECT: GRB110915A MITSuME Okayama J-band upper-limit DATE: 11/09/16 04:24:57 GMT FROM: Daisuke Kuroda at OAO/NAOJ Kenshi Yanagisawa, Daisuke Kuroda, Yasuhiro Shimizu, Kiichi Okita (OAO/NAOJ), Michitoshi Yoshida (Hiroshima-U), Kouji Ohta(Kyoto-U) and Nobuyuki Kawai(Tokyo Tech.) report on behalf of the MITSuME collaboration. We observed the field of GRB110915A (Holland et al, GCN12355) in J-band with a wide-field near infrared imager at Okayama Astrophysical Observatory (Japan). The imager has effective aperture of 0.91 m. Observations started from 15:19 UT on 15th September, just 2 hours after the BAT trigger, to 16:02 UT. The total exposure of 35 min was successfully obtained. In our co-add image, we did not find any new point source within the enhanced XRT error circle (P.A. Evans et al., GCNC 12340) down to limiting magnitude of J=17.3 (Vega, S/N=3) . The photometric calibration was made against 2MASS field stars. T0+[s] MID-UT T-EXP[sec] J --------------------------------------------------- +8130 15:35 2110 >17.3 --------------------------------------------------- T0+ : Elapsed time after the burt [sec] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12346 SUBJECT: GRB 110915A: Deep Gemini-South i/z-band imaging DATE: 11/09/16 04:40:32 GMT FROM: Daniel Perley at U.C. Berkeley D. A. Perley (Caltech), A. Cucchiara (UC Santa Cruz), and N. R. Tanvir (Leicester) report on behalf of a larger collaboration: We imaged the field of GRB 110915A (Holland et al., GCN 12335) with GMOS-S on Gemini-South starting at 00:36 UT on 2011-09-16. We acquired 6x240 seconds in i-band, and 7x240 seconds in z-band. Conditions were clear with generally good seeing (0.7"). We find no significant sources within the XRT error circle in either filter. We calculate the following 3-sigma limits: i > 26.0 mag (t_mid = 11.49 hr) z > 24.9 mag (t_mid = 12.03 hr) Given the bright X-ray afterglow and and other optical limits reported to date, these results indicate that GRB 110915A is a very dark burst, as also noted by Malesani et al (GCN 12343). Infrared and radio follow-up is encouraged. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12348 SUBJECT: GRB 110915B: XRT afterglow candidate DATE: 11/09/16 12:05:21 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo (INAF-OAB), J. K. Cannizzo (NASA/UMBC), P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team: At 04:36:53 UT, September 16, 2011, Swift began a Target of Opportunity observation of the AGILE discovered burst GRB 110915B (Del Monte et al. et al. GCN Circ. 12341). We have analysed 2.1 ks of XRT data, from 36.8 ks to 43.2 ks after the AGILE trigger. The data are entirely in Photon Counting (PC) mode. An uncatalogued X-ray source is detected within the AGILE error circle. Using 2132 s of PC mode data and 3 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 77.55470, +1.93280 which is equivalent to: RA (J2000): 05h 10m 13.13s Dec(J2000): +01d 55' 57.9" with an uncertainty of 1.8 arcsec (radius, 90% confidence). This position is 37 arcsec from the AGILE position. The light curve is consistent with a constant source of mean count rate 7.1e-02 ct/sec. A power-law fit gives an index of -0.3 (+2.3, -1.1). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.85 (+0.36, -0.27). The best-fitting absorption column is 9 (+10, -1) x 10^20 cm^-2, consistent with the Galactic value of 8.5 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 3.9 x 10^-11 (4.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 9 (+10, -1) x 10^20 cm^-2 Galactic foreground: 8.5 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.85 (+0.36, -0.27) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020185. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12349 SUBJECT: GRB 110915A: Deep Near-IR Limits from Magellan DATE: 11/09/16 12:27:01 GMT FROM: Edo Berger at Harvard E. Berger, R. Chornock, J. Strader (Harvard) and L. Spitler (Swinburne) report: "We imaged the field of GRB 110915A (GCN 12335) with the FourStar near-IR imager mounted on the Magellan/Baade 6.5-m telescope starting on 2011 Sep 16.155 UT (14.4 hr after the burst). Observations were obtained in the J and Ks filters in good seeing (0.6"). We do not detect any sources in coincidence with the enhanced XRT position (GCN 12340) to a 3-sigma limit of J>23.5 mag and Ks>23.0 mag (AB). The X-ray flux on the same timescale (extrapolated from the existing XRT light curve) is F_X ~ 4e-12 cgs, indicating an expected near-IR brightness of J~19 mag and K~18.5 mag. If due to extinction, the required ~4.5 mag in J and Ks are suggestive of an unusually large A_V." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12350 SUBJECT: GRB 110915B: Afterglow candidate from OSN DATE: 11/09/16 13:22:14 GMT FROM: Antonio Deugarte at IAA-CSIC A. de Ugarte Postigo (DARK/NBI), J. C. Tello, V. Casanova, A. J. Castro-Tirado, R. Sanchez-Ramirez, J. Gorosabel, S. Guziy (IAA-CSIC) D. Malesani (DARK/NBI) report on behalf of a larger collaboration: We have observed the field of the AGILE GRB 110915B (Del Monte et al. GCNC 12341) using the 1.5m OSN telescope at Sierra Nevada Observatory (Granada, Spain). The observation consisted of 46 x 120s exposures in R-band. In the combined exposure we detect an uncatalogued source inside the error box of the XRT afterglow candidate (D'Avanzo et al. GCNC 12348) at the following coordinates (J2000, +/- 0.5"): R.A.: 05:10:13.14 Dec.: +01:55:59.1 The preliminary magnitude of the object at an average epoch of Sep. 16.166 UT (9.59 hr after the burst onset) is R = 22.8+/-0.30, as compared to the USNO-B1.0 star at coordinates 05:10:09.720, +01:56:40.12, for which we assume R = 17.61. Further analysis is ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12351 SUBJECT: GRB 110915A: Swift-XRT refined Analysis DATE: 11/09/16 13:30:40 GMT FROM: Boris Sbarufatti at INAF-OAB/IASFPA B. Sbarufatti (INAF-OAB/IASFPA) and S. T. Holland (CRESST/USRA/GSFC) report on behalf of the Swift-XRT team: We have analysed 3.3 ks of XRT data for GRB 110915A (Holland et al. GCN Circ. 12335), from 82 s to 7.7 ks after the BAT trigger. The data comprise 1.6 ks in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 12336). The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=5.6 (+0.6, -0.4). At T+120 s the decay flattens to an alpha of 0.49 (+0.15, -1.09) before breaking again at T+309 s to a final decay with index alpha=0.84 (+0.04, -0.03). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.98 (+/-0.05). The best-fitting absorption column is 2.69 (+0.18, -0.17) x 10^21 cm^-2, in excess of the Galactic value of 5.3 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.04 (+0.21, -0.20) and a best-fitting absorption column of 2.6 (+/-0.7) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (6.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.6 (+/-0.7) x 10^21 cm^-2 Galactic foreground: 5.3 x 10^20 cm^-2 Excess significance: 6.5 sigma Photon index: 2.04 (+0.21, -0.20) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00503219. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12352 SUBJECT: GRB 110915A, Swift-BAT refined analysis DATE: 11/09/16 14:33:10 GMT FROM: Hans Krimm at NASA-GSFC T. N. Ukwatta (MSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), S. T. Holland (CRESST/USRA/GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC), (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 110915A (trigger #503219) (Holland, et al., GCN Circ. 12335). The BAT ground-calculated position is RA, Dec = 310.830, -0.713 deg which is RA(J2000) = 20h 43m 19.2s Dec(J2000) = -00d 42' 45.8" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 25%. The light curve consists first of a group of multiple overlapping peaks lasting from T0-5 sec to T0+45 sec. This is followed by a second cluster from T0+55 sec to T0+85 sec, containing the brightest peak at ~T0+70 sec. T90 (15-350 keV) is 78.76 +- 1.25 sec (estimated error including systematics). The time-averaged spectrum from -2.74 to 92.1 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.94 +- 0.23, and Epeak of 124.8 +- 41.4 keV (chi squared 58.07 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 5.7 +- 0.2 x 1006 erg/cm2 and the 1-sec peak flux measured from T+68.04 sec in the 15-150 keV band is 3.3 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.41 +- 0.05 (chi squared 72.11 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/503219/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12353 SUBJECT: GRB 110915A: GROND Upper limits DATE: 11/09/16 18:32:42 GMT FROM: Alexander Kann at TLS Tautenburg J. Elliott (MPE Garching), D. A. Kann (Tautenburg Obs.), and J. Greiner (also MPE Garching) report on behalf of the GROND team: We observed the field of GRB 110915A (Swift trigger 503219; Holland et al., GCN 12335) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPI/ESO telescope at La Silla Observatory (Chile). Observations started at 23:26 UT on 15 September, 10.1 hours after the GRB trigger. They were performed at an average seeing of 1.1 and at an average airmass of 1.2. We do not detect a source within the enhanced UVOT/Swift-XRT error circle reported by Evans et al. (GCN 12340). For a total exposure time of 6003 s in g'r'i'z' and 4800 s in JHK, we do not detect a source down to: g' > 25.5, r' > 25.4, i' > 24.3, z' > 23.8, J > 21.2, H > 20.0, and K > 18.6 The given limits are derived based on calibrating the images against GROND zeropoints (g'r'i'z' are AB mags) and 2MASS field stars (JHK are Vega mags) and are not corrected for the Galactic foreground extinction corresponding to a reddening of E(B-V) = 0.058 in the direction of the burst (Schlegel et al. 1998). These upper limits are in agreement with the i/z upper limits from Perley et al. (GCN 12346) and the J/Ks upper limits from Berger et al. (GCN 12349). [GCN OPS NOTE(16sep11): Per author's request, the date in the second paragraph was corrected from "16 Sep" to "15 Sep", and Perley citation was changed from "12345" to "12346".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12354 SUBJECT: GRB 110915B: Swift/UVOT Upper Limits DATE: 11/09/16 21:12:10 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and J. K. Cannizzo (GSFC/UMBC/CRESST) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 110915B 36,747 s after the AGILE trigger (Del Monte et al., GCN Circ. 12341). No optical afterglow consistent with the position of the X-ray (D'Avanzo et al. GCN Circ.12348) or optical (de Ugarte Postigo et al., GCN Circ. 12350) afterglow candidates 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 initial exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 37077 48670 1468 >22.2 v 42882 48935 542 >20.1 u 36747 52898 1869 >22.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.07 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12355 SUBJECT: GRB 110915A: Swift/UVOT Upper Limits DATE: 11/09/17 20:18:06 GMT FROM: Erik Hoversten at Swift/Penn State E. A. Hoversten (PSU) and S. T. Holland (CRESST/USRA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 110915A 84 ks after the BAT trigger (Holland et al., GCN Circ. 12335). No optical afterglow consistent with the enhanced XRT position (Evans et al., GCN Circ. 12340) is detected in the initial UVOT exposures. UVOT magnitude 3-sigma upper limits are reported in the following table: Filter T_start T_stop Exp(s) Mag (3-sigma upper limit) ------------------------------------------------------------- white 84 1884 429 > 21.46 v 616 5316 203 > 19.35 b 540 1858 136 > 20.10 u 284 1834 362 > 20.36 uvw1 665 1809 136 > 19.59 uvm2 641 1784 136 > 19.46 uvw2 592 1897 144 > 19.82 The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight of E_(B-V) = 0.06 (Schlegel et al. 1998). All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12356 SUBJECT: GRB 110915B: GROND Observations of the Optical/NIR Afterglow Candidate DATE: 11/09/19 16:23:34 GMT FROM: Alexander Kann at TLS Tautenburg J. Elliott (MPE Garching), D. A. Kann (TLS Tautenburg), and J. Greiner (also MPE Garching) report on behalf of the GROND team: We observed the field of the AGILE GRB 110915B (E. Del Monte et al., GCN 12341) 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 were taken starting at 06:59 UT on 18 September 2011 (2.5 days after the GRB trigger). They were performed at an average seeing of 1".4 and at an airmass of 2, with the Moon only 22 degrees away. We detect the afterglow candidate reported by A. de Ugarte Postigo et al. (GCN 12350). Based on an exposure time of 4502 s in the optical, we estimate an r' magnitude (in AB) of: r' = 23.2 +/- 0.1. Compared to the magnitudes reported by A. de Ugarte Postigo et al., the candidate shows no decay over the past 2.1 days and so is likely not the GRB afterglow. We find a flux ratio between optical and X-rays of f_x/f_opt = 4500 which indicates an AGN nature if the X-ray emission (P. D'Avanzo et al., GCN 12348) has not faded. Given magnitudes are calibrated against GROND zeropoints and shifted based on the USNO-B1.0 star used by A de Ugarte Postigo., RA = 05:10:09.720, Dec. = +01:56:40.12, and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E(B-V) = 0.07 in the direction of the burst (Schlegel et al. 1998). We are indebted to A. de Ugarte Postigo for providing us a finding chart. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12358 SUBJECT: GRB 110915A: Konus-Wind and Swift/BAT joint spectral analysis DATE: 11/09/19 21:22:41 GMT FROM: Valentin Pal'shin at Ioffe Inst V. Pal'shin, S. Golenetskii, R.Aptekar, E. Mazets, D. Frederiks, and T. Cline on behalf of the Konus-Wind team, T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), and T. Ukwatta (GWU) report: We performed the Konus-Wind and the Swift/BAT joint spectral analysis of GRB 110915A (Swift/BAT trigger #503219: Holland et al., GCN Circ. 12335, Ukwatta et al. GCN Circ. 12352). Since the Konus-Wind observed this GRB in the waiting mode, we only have 3 channel spectral data for the Konus-Wind which cover the energy range from 20 keV to 1.2 MeV. The joint spectral analysis of the Konus-Wind and the Swift/BAT data allows us to derive the broad-band spectral parameters of this burst. The time interval of the spectral data for each instrument is chosen from T0(BAT)-3.3 to T0(BAT)+82.1 s where T0(BAT) is the trigger time of BAT at 13:20:44.40 UTC. The energy ranges which we used in the joint spectral analysis are 20-1200 keV and 14-150 keV for the Konus-Wind and the Swift/BAT respectively. The spectral data of two instruments are fitted with the spectral model multiplied by the constant factor to take into account the systematic effective area uncertainties in the response matrices of each instrument. The spectrum is well fitted with a power-law with exponential cutoff model: dN/dE ~ E^{alpha}*exp(-(2+alpha)*E/Epeak). No systematic residual from the best fit model is seen in the spectral data of each instrument. The BAT constant factor is 0.76(-0.08,+0.09) (the KW constant factor is fixed to 1). The best fit spectral parameters are: alpha = -1.08 (-0.14/+0.19) and Epeak = 183 (-48/+80) keV (chi2/dof = 62/58). The best fit spectral parameters for the GRB (Band) model are: alpha = -0.90(-0.21,+0.24), beta = -2.2(-0.8,+0.3), and Epeak = 132(-28,+57) keV (chi2/dof = 58/57). The derived alpha and Epeak are in agreement with those derived from analysis of the BAT data alone (Ukwatta et al. GCN Circ. 12352). The energy fluence in the 15-1200 keV band calculated by a power-law with exponential cutoff model for this 85.4 s interval is 1.35(-0.20,+0.25)x10^-5 erg/cm2. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB110915A/ All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12372 SUBJECT: GRB 110915B : X-ray afterglow confirmation DATE: 11/09/21 12:14:05 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo (INAF-OAB), J. K. Cannizzo (NASA/UMBC), P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team: Swift continued to monitor the field of the AGILE-detected GRB 110915B (Del Monte et al. GCN Circ. 12341). We have analysed 6.1 ks of XRT data, from 36.8 ks to 442.2 ks after the AGILE trigger. The data comprise 148 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The X-ray source reported in D'Avanzo et al. (GCN Circ. 12348) has faded to a level of 5.8e-3 ct/sec. The light curve can be modelled with a power-law decay with a decay index of alpha=1.05 (+0.57, -0.25). The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020185. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12786 SUBJECT: GRB 110915A, the review of the sky area in plate archives DATE: 11/12/30 17:58:18 GMT FROM: Valentyna Golovnya at Main Astro Obs,Kyiv V.V. Golovnya (Main Astro Obs, Kyiv) report: We have undertaken the review of the sky area in vicinity of GRB 110915A (Evans et al., GCN Circ.12340) on astronegatives, collected in Ukrainian NAS Main astronomical observatory plate archive (1976-1996). All the plates with the possible object appearance are digitized using Microtek ScanMaker 9800XL TMA and Epson Expression 10000XL flatbed scanners and have been placed into Golosiiv Plate Archive database DBGPA with open access to them. The list of plates is given in the table: YYYYMMDD/TimeUT --Plates-- Exp. LimMag Star USNOA2 19810930/180433 GUA040C000001A 27.0 16.50 0825-18636133 19820827/205711 GUA040C002422 60.3 14.40 0825-18638528 19820827/205711 GUA040D002423 60.3 14.40 0825-18638528 19820827/223853 GUA040C002424 15.0 13.75 0825-18638504 19820909/165505 TAS040A000325 23.0 17.10 0825-18635715 19820918/160521 TAS040A000331 23.0 16.50 0825-18636133 19910709/231157 GUA040C001830A 22.5 15.50 0825-18638699 Plates: GUA040C,–the plates archive identifier of DWA (D/F=400/2000, GUA040D M=103"/mm) of the Ukrainian NAS Main Astro obs. (Marsden's number - 83) the plate number [1]. TAS040A -the plates archive identifier of DAZ (D/F=400/3000, M=68.8"/mm) of the Tashkent Astro obs. (Marsden's number - 186) the plate number [1]. Exp. - Duration of the maximum exposure (minutes). LimMag - Limited V mag, derived in the 15 minutes area around the location given in GCN Circ.12340: RA(J2000): 20h 43m 17.87s, Dec(J2000): -00d 43' 23.2" Star USNOA2 - Comparison star. The preview images of 7 areas together with the 15x15 min.of arc area from SkyMap can be found in http://gua.db.ukr-vo.org/img/grb/110915A/index.html The images with full resolution are available via e-mail on demand. References: 1.L.Pakuliak DATABASE of GOLOSIIV PLATE ARCHIVE (DBGPA V2.0), http://gua.db.ukr-vo.org //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 12827 SUBJECT: GRB 110915B, the review of the sky area in plate archives DATE: 12/01/11 17:56:57 GMT FROM: Valentyna Golovnya at Main Astro Obs,Kyiv V.V.Golovnya (Main Astro Obs, Kyiv) report: We have undertaken the review of the sky area in vicinity of GRB 110915B (P. D'Avanzo et al. GCN Circ.12348) on astronegatives, collected in Ukrainian NAS Main astronomical observatory plate archive (1976-1996). All the plates with the possible object appearance are digitized using Microtek ScanMaker 9800XL TMA and Epson Expression 10000XL flatbed scanners and have been placed into Golosiiv Plate Archive database DBGPA with open access to them. The list of plates is given in the table: YYYYMMDD/TimeUT --Plates-- Exp. LimMag Star USNOA2 19820210/174605 GUA040C000008A 27.0 15.70 0900-01403360 19820210/174605 GUA040D000009 27.0 15.70 0900-01403360 19911011/014851 GUA040C001873 25.1 15.05 0900-01404372 19911012/015416 GUA040C001880A 18.2 15.05 0900-01408313 19920108/200727 GUA040C001916 23.0 16.45 0900-01406794 19920201/181314 GUA040C001929A 23.0 15.05 0900-01408313 Plates: - the plates archive identifier of DWA (D/F=400/2000, GUA040C, M=103"/mm) of the Ukrainian NAS Main Astro obs. GUA040D (Marsden's number - 83) the plate number [1]. Exp. - Duration of the maximum exposure (minutes). LimMag - Limited V mag, derived in the 17 minutes area around the location given in GCN Circ.12348: RA(J2000) = 05h 10m 13.13s, Dec(J2000) = +01d 55'57.9" Star USNOA2 - Comparison star. The preview images of 6 areas together with the 17x17 min.of arc area from SkyMap can be found in http://gua.db.ukr-vo.org/img/grb/110915B/index.html The images with full resolution are available via e-mail on demand. References: 1.L.Pakuliak DATABASE of GOLOSIIV PLATE ARCHIVE (DBGPA V2.0), http://gua.db.ukr-vo.org