//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18246 SUBJECT: GRB 150907A: MAXI/GSC detection DATE: 15/09/07 17:46:13 GMT FROM: Motoko Suzuki at RIKEN Y. E. Nakagawa (JAXA), H. Negoro, (Nihon U.), M. Serino (RIKEN), M. Ishikawa, S. Nakahira, S. Ueno, H. Tomida, M. Kimura(JAXA), T. Mihara, M. Sugizaki, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N. Kawai, Y. Tachibana, T. Yoshii (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, R. Imatani (Osaka U.), M. Nakajima, T. Masumitsu, K. Tanaka (Nihon U.), Y. Ueda, T. Kawamuro, T. Hori (Kyoto U.), Y. Tsuboi, S. Kanetou (Chuo U.), M. Yamauchi, D. Itoh (Miyazaki U.), K. Yamaoka (Nagoya U.), M. Morii (ISM) report on behalf of the MAXI team: The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 16:00:50 UT on 7 September 2015. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (224.845 deg, -47.592 deg) = (14 59 22, -47 35 31) (J2000) with a 90% C.L. statistical error of 0.06 deg. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 1464 +- 75 mCrab (4-10keV, 1 sigma error). There was no significant excess flux in the previous transit at 14:28 UT on 7 September 2015 with an upper limit of 20 mCrab. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18247 SUBJECT: GRB 150907A: Tiled Swift observations DATE: 15/09/07 18:37:17 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a series of observations, tiled on the sky, of the MAXI GRB 150907A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00048 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the MAXI event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18250 SUBJECT: GRB 150907A: Swift-XRT observations DATE: 15/09/08 00:52:27 GMT FROM: Tineke Roegiers at PSU J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), T.G.R. Roegiers (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. D'ai (INAF-IASFPA), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the MAXI-detected burst GRB 150907A (Nakagawa et al. GCN Circ. 18246) in a series of observations tiled on the sky. The total exposure time is 1.7 ks, distributed over 4 tiles; the maximum exposure at a single sky location was 1.1 ks. The data were collected between T0+8.8 ks and T0+18.8 ks, and are entirely in Photon Counting (PC) mode. One uncatalogued X-ray source has been detected, it is below the RASS limit and shows no definitive signs of fading. Therefore, at the present time we cannot confirm this as the afterglow. Details of this source are given below: Source 1: RA (J2000.0): 225.0526 = 15:00:12.62 Dec (J2000.0): -47.7084 = -47:42:30.3 Error: 6.0 arcsec (radius, 90% conf.) Count-rate: 0.037 +/- 0.010 ct s^-1 Flux: (2.50 +/- 0.70)e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV) The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00048. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18255 SUBJECT: GRB150907A: Swift/UVOT observations DATE: 15/09/08 11:57:36 GMT FROM: Massimiliano de Pasquale at IASF-Palermo M. De Pasquale (UCL-MSSL) and D. Malesani (DARK/NBI) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150907A 8821 s after the MAXI trigger (Suzuki et al., GCN Circ. 18246). No optical source consistent with the XRT Source 1 position given in Kennea et al. (GCN Circ. 18250) is detected in the summed u band exposures. We note however, that there is source in the DSS catalogue consistent with the XRT Source 1 position. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the exposure for source 1 is: Filter T_start(s) T_stop(s) Exp(s) Mag u 8821 18835 336 >19.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.08 in the direction of the burst (Schlegel et al. 1998). -- Dr. Massimiliano De Pasquale Research associate - Swift UVOT scientist Mullard Space Science Laboratory, University College London //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18311 SUBJECT: GRB 150907A: Swift-XRT afterglow detection DATE: 15/09/14 16:02:36 GMT FROM: Boris Sbarufatti at INAF-OAB/IASFPA J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. D'ai (INAF-IASFPA), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has conducted further observations of the field of the MAXI-detected burst GRB 150907A (Nakagawa et al. GCN Circ. 18246). The observations now extend from T0+8.8 ks to T0+489.4 ks. The source previously reported by Kennea et al. (GCN Circ. 18250), "Source 1", is fading with 3-sigma significance, and is therefore likely the GRB afterglow. The position of this source is RA, Dec=225.0528, -47.7080 which is equivalent to: RA (J2000): 15:00:12.68 Dec(J2000): -47:42:28.8 with an uncertainty of 6.8 arcsec (radius, 90% confidence). This position is 10.9 arcmin from the MAXI position. The source is fading with alpha >0.5. The results of the XRT-team automatic analysis of the likely afterglow are at http://www.swift.ac.uk/xrt_products/TILED_GRB00048/index_1.php. The results of the full analysis of the tiled XRT observations are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00048. This circular is an official product of the Swift-XRT team.