//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8852 SUBJECT: GRB 090126: SuperAGILE Localization of a Long GRB DATE: 09/01/26 08:35:37 GMT FROM: Marco Feroci at IASF/INAF Y. Evangelista, E. Del Monte, I. Donnarumma, M. Feroci, F. Lazzarotto, L. Pacciani, P. Soffitta, E. Costa, I. Lapshov, M. Rapisarda (INAF/IASF Rome), A. Giuliani, S. Vercellone, A. Chen, S. Mereghetti, A. Pellizzoni, F. Perotti, P. Caraveo (INAF/IASF Milan), A. Bulgarelli, F. Gianotti, M. Trifoglio, G. Di Cocco, C. Labanti, F. Fuschino, M. Marisaldi, M. Galli, (INAF/IASF Bologna), M. Tavani, G. Pucella, F. D'Ammando, V. Vittorini, A. Argan, A. Trois, G. Piano, S. Sabatini (INAF/IASF Rome), G. Barbiellini, F. Longo E. Moretti (INFN Trieste), P. Picozza, A. Morselli (INFN Roma-2), M. Prest, E. Vallazza (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), and P. Giommi, C. Pittori, B. Preger, P. Santolamazza, F. Verrecchia (ASDC) and L. Salotti (ASI), on behalf of the AGILE Team, report: "SuperAGILE detected a gamma ray burst on 26 January 2009, at 02:01:15 UT. The event had a duration of about 60 s in the 20-60 keV energy range, with a structure composed of two separated main peaks. Assuming a Crab-like energy spectrum, the peak flux on 1-s timescale was 1.5E-07 erg/cm2/s. The burst position was reconstructed as (RA, Dec) (3.848 deg, 81.365 deg), which is: RA(J2000) = 00h 15m 23.50s Dec(J2000) = 81d 21' 53.78" with an uncertainty of 3' 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: 8853 SUBJECT: GRB 090126B: Fermi GBM detection DATE: 09/01/26 16:31:43 GMT FROM: Andreas von Kienlin at MPE A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 05:26:22.23 UT on 26 January 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090126B (trigger 254640384 / 090126227 ). The on-ground calculated location, using the GBM trigger data, is RA = 190.5, DEC = 33.2 (J2000 degrees, equivalent to 19h 42m, 33d 12'), with an uncertainty of 4.4 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 18 degrees. The GBM light curve consists of a single peak with a duration (T90) of about 10.8 s (8-1000 keV). The time-averaged spectrum from T0-4.608 s to T0+5.632 s is best fit by a power law function with an exponential high energy cutoff. The power law index is -0.99 +/- 0.18 and the cutoff energy, parameterized as Epeak, is 47.5 +/- 3.4 keV (chi squared 404.17 for 360 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.25 +/- 0.24)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.512 s in the 8-1000 keV band is 4.9 +/- 1.3 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: 8854 SUBJECT: GRB 090126A: Swift-XRT Refined Analysis DATE: 09/01/27 01:23:41 GMT FROM: Michael Stroh at PSU/Swift M. C. Stroh (PSU) reports on behalf of the Swift-XRT team: We have analyzed the first 3.1 ks of XRT data for GRB 090126A (Evangelista et al., GCN Circ. 8852), from T+48 ks to T+60 ks after the trigger. The data is all taken in Photon Counting (PC) mode. Using 1435 s of XRT Photon Counting mode data and 2 UVOT images, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching to the USNO-B1 catalogue): RA, Dec = 3.6577, 81.3733 which is equivalent to: RA (J2000): 00 14 37.85 Dec (J2000): +81 22 24.0 with an uncertainty of 2.2 arcsec (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 http://www.swift.ac.uk/xrt_positions/Goad.pdf) , the current algorithm is an extension of this method. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.8 (+0.6, -0.4). The best- fitting absorption column is 1.8 (+/- 1.8) x 10^21 cm^-2, which is consistent with the Galactic value of 1.4 x 10^21 cm^-2 (Kalberla et al. 2005). The observed (unabsorbed) flux in the 0.3-10.0 keV band is 1.49 (1.9) x 10^-12 erg cm^-2 s^-1. The light curve shows a potentially decaying source which can be fit using a single power-law decay with a slope, alpha = 1.2 (+/- 1.1). Assuming the light curve decays at the current rate, we predict count rates at T+24 and T+48 hours to be 1.6 x 10^-2 and 7.0 x 10^-3 respectively. This is an official product of the Swift-XRT team.//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8855 SUBJECT: GRB 090126C: Fermi GBM detection DATE: 09/01/27 16:24:35 GMT FROM: Andreas von Kienlin at MPE A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 05:52:33.73 UT on 26 January 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090126C (trigger 254641955 / 090126245). The on-ground calculated location, using the GBM trigger data, is RA = 222.9, DEC = 39.2 (J2000 degrees, equivalent to 14h 52m, 39d 12'), with an uncertainty of 14.6 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 68 degrees. Since this GRB is weak and short (~ 1 sec), the time-averaged spectrum is poorly constrained." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8864 SUBJECT: GRB 090126A: Swift/UVOT Upper Limits DATE: 09/01/30 18:03:40 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. T. Holland (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC), and M. C. Stroh (PSU) report, on the behalf of the Swift/UVOT team: The Swift/UVOT observed the field of GRB 090126A (Evangelista et al. 2009, GCN Circ. 8852) starting approximately 48 ks after the SuperAGILE detection. We find no new source, relative to the DSS or USNO-B1.0 catalogue, or a variable source, inside the UVOT-enhanced XRT error circle (Stroh et al. 2009, GCN Circ. 8854). Preliminary 3-sigma upper limits for detecting a source in the co-added images, using an aperture-corrected 2.5 arcsecond radius circular aperture, are Filter T_start T_stop Exp(s) Mag ------------------------------------------ v 49,398 55,302 208 >20.1 b 48,033 71,752 3256 >22.7 u 47,960 71,155 333 >21.0 white 48,713 66,162 2022 >23.1 ------------------------------------------ The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight corresponding to a reddening of E_{B-V} = 0.20 mag (Schlegel et al., 1998, ApJS, 500, 525). All photometry is on the UVOT photometry system described in Poole et al. (2008, MNRAS, 383, 627). Please update my e-mail address in your Address Book to . / \ / //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8880 SUBJECT: GRB 090126A: Swift-XRT afterglow confirmation DATE: 09/02/03 16:43:33 GMT FROM: Michael Stroh at PSU/Swift M. C. Stroh (PSU) reports on behalf of the Swift-XRT team: Swift took an additional 7.6ks observation of GRB 090126A centered at T +29ks after the trigger. The single uncatalogued X-ray source previously reported by Stroh et al. (GCN Circ. 8854) shows fading flux, confirming its afterglow nature. The 0.3-10 keV light curve can be fit using a simple power law model with decay index alpha = 1.42 +/- 0.13. This is an official product of the Swift-XRT team.