//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10977 SUBJECT: GRB 100724B: Fermi GBM detection DATE: 10/07/24 23:28:20 GMT FROM: Narayana Bhat at U Alabama/Huntsville/GBM P. N. Bhat (UAH) reports on behalf of the Fermi GBM Team: "At 00:42:05.98 UT on 24 July 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100724B (trigger 301624927 / 100724029). The on-ground calculated location, using the GBM trigger data, is RA = 124.16, DEC = 74.42 (J2000 degrees, equivalent to 08 h 16.6 m, 74 d 25.2 '), with an uncertainty of 1.0 degree (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 52 degrees. GBM triggered an automatic repoint request to the Fermi Observatory to execute a maneuver following this trigger and track the burst location for the next 5 hours. However due to spacecraft constraints, the slew did not commence until 2733 s after the trigger. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve consists of several pulses with a duration (T90) of about 111.6 s (50-300 keV). The time-averaged spectrum from T0-5.12 s to T0+140.29 s is best fit by a Band function with Epeak = 467.8 +15.3/-13.1 keV, alpha = 0.84 +/- 0.01, and beta = -1.84 +/- 0.01 (Cstat 18069 for 736 d.o.f.). The event fluence (8-1000 keV) in this time interval is (2.44 +/- 0.006)E-04 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+52 s in the 8-1000 keV band is 7.06 +/- 0.01 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: 10978 SUBJECT: GRB 100724B: Fermi LAT and GBM analysis DATE: 10/07/25 04:32:20 GMT FROM: James Chiang at SLAC Yasuyuki Tanaka, Masanori Ohno (ISAS/JAXA), Hiromitsu Takahashi, Takeshi Uehara (Hiroshima University), Nicola Omodei (Stanford Univ.), James Chiang (SLAC) and Sylvain Guiriec (UAH) report on behalf of the Fermi LAT and GBM teams: At 00:42:06 UT on 24 July 2010, the Fermi Large Area Telescope (LAT) detected gamma-rays from the long GRB 100724B. This burst was detected and localized by the Fermi Gamma-Ray Burst Monitor (GBM) (trigger 301624927 / 100724029, GCN 10977). The best LAT on-ground localization for this burst is RA, Dec = 120.04, 76.74 (08h 00m 09.6s, 76d 44' 24", J2000) with a 90% containment radius of 1.1 degrees (statistical; 68% containment radius 0.6 degrees). At the GBM trigger time, this location was at angle of 49 degrees from the LAT boresight and approximately 18 degrees from the Earth's limb. The GBM trigger caused an Autonomous Repoint Request. However, owing to the proximity of the burst location to the Earth horizon and constraints on the spacecraft pointing, the angle of the source with respect to the boresight remained greater than 40 degrees for the first 2700 seconds after trigger. Using a non-standard data selection designed to maximize the low energy acceptance, the LAT light curve shows two distinct peaks at ~20 and ~64 s after the GBM trigger and a smaller sub-peak at ~77 s post-trigger. A joint spectral fit with the GBM data yields a photon index in the LAT band (> 20 MeV) of -2.48 +/- 0.01 (stat). This is consistent with an extrapolation of the high energy part of the spectrum in the GBM band. This result differs somewhat from the fit reported in GCN 10977. In order to account for a spectral feature below 100 keV, we have included a low energy spectral component in addition to the usual Band function model; this accounts for the difference found in the high energy photon index. Further analysis is ongoing. The Fermi LAT point of contact for this burst is Yasuyuki Tanaka (tanaka@astro.isas.jaxa.jp). The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. [GCN OPS NOTE(24aug10): Per author's request, the date in the first line was changed from "25 July" to "24 July".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10981 SUBJECT: Konus-Wind observation of GRB 100724B DATE: 10/07/25 09:34:14 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The bright long hard GRB 100724B (Fermi/GBM trigger 301624927: Bhat, GCN 10977; localized by Fermi/LAT: Tanaka et al., GCN 10978) triggered Konus-Wind at T0=2526.266s UT (00:42:06.266) The burst light curve shows a complex structure with a total duration of ~240 s. It consists of an initial harder part, ~90 s in duration, followed by a softer one, lasting to T0 + 230 s. The emission is seen up to 10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB100724_T02526/ As observed by Konus-Wind the burst had a fluence of 4.1(+/-0.3)x10-4 erg/cm2, and a 256-ms peak flux, measured from T0+59.648s, of 1.0(+/- 0.1)x10-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+228.608 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model, for which: the low-energy photon index alpha = -0.87 (-0.06, +0.06), the high energy photon index beta = -2.0 (-0.09, +0.07), the peak energy Ep = 369(-37, +42)keV (chi2 = 86/87 dof). The spectrum at the maximum count rate (measured from T0+57.856 to T0+61.952 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model, for which: the low-energy photon index alpha = -0.8 (+/-0.1), the high energy photon index beta = -2.1 (+/-0.15), the peak energy Ep = 418(-58, +66)keV (chi2 = 84/87 dof). All the quoted results are preliminary. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10994 SUBJECT: GRB 100724B: gamma-ray detection by AGILE DATE: 10/07/26 14:36:30 GMT FROM: Martino Marisaldi at INAF-IASF M. Marisaldi, F. Fuschino, C. Labanti, M. Galli, A. Bulgarelli, F. Gianotti, M. Trifoglio, G. Di Cocco (INAF/IASF Bologna), 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. Giuliani, A. Chen, S. Mereghetti, F. Perotti, P. Caraveo (INAF/IASF Milan), M. Tavani, 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: "The AGILE Gamma-Ray Imaging Detector (GRID) and Mini-Calorimeter (MCAL) detected at gamma-ray energies the long bright GRB 100724B (Bhat, GCN 10977; Tanaka et al., GCN 10978; Golenetskii et al., GCN 10981). The GRB triggered AGILE-MCAL, sensitive in the energy range 330 keV - 100 MeV, on 24 July 2010 at 00:42:00 UT (T0). As seen by MCAL the burst has a duration (T90) of ~96 s, with observable emission up to ~T0+150 s. The GRB emission has significant detection in MCAL up to an energy of about 80 MeV. The time integrated spectrum in the time interval [T0, T0+150.0 s] can be fit in the energy range 500 keV - 80 MeV with a single powerlaw with photon index -2.09 (-0.06, +0.08) (reduced chi2 = 0.94 with 39 d.o.f.). The estimated fluence is (2.7 ± 0.2)x10-4 erg/cm2 in the same energy range. All reported errors are at the 90% confidence level. AGILE-GRID shows a definite detection above 100 MeV. Further analysis are in progress. This message may be cited." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10995 SUBJECT: GRB 100724B: Suzaku WAM observation of the prompt emission DATE: 10/07/26 15:09:31 GMT FROM: Takeshi Uehara at Hiroshima U T. Uehara, Y. Hanabata, T. Takahashi, Y. Fukazawa (Hiroshima U.), N. Vasquez (Tokyo Tech.) K. Yamaoka (Aoyama Gakuin U.), S. Sugita (Nagoya U.), Y. Terada, M. Tashiro, W. Iwakiri, K. Takahara, T. Yasuda (Saitama U.), M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA), Y. E. Nakagawa, T. Tamagawa (RIKEN), N. Ohmori, A. Daikyuji, Y. Nishioka, M. Yamauchi (Univ. of Miyazaki), Y. Urata, H. M. Lin, P. Tsai (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo), S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report: The bright long GRB 100724B (Fermi/GBM trigger #301624927 ; P. N. Bhat et al., GCN 10977) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 00:42:04.70 UT (=T0). The observed light curve shows a multi-peaked structure starting at T0-7s, ending at T0+143s with a duration (T90) of about 103 seconds. The fluence in 100 - 1000 keV was 1.63(+0.03/-0.07) x 10^-4 erg/cm^2. The 1-s peak flux measured from T0+65s was 9.3 photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-4.1s to T0+141.3s is well fitted by a power-law with exponential cutoff model: dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with alpha 1.09 (+0.18/-0.19), and Epeak 666 (+107/-67) keV (chi^2/d.o.f. = 22.8/22). All the quoted errors are at statistical 90% confidence level. The light curves for this burst are available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html The light curves with 1-sec time resolution for this burst will be appeared at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10996 SUBJECT: GRB 100724B: AGILE/GRID analysis DATE: 10/07/26 16:21:05 GMT FROM: Marco Feroci at IASF/INAF A. Giuliani (INAF/IASF Milano), M. Tavani (INAF/IASF Roma), F. Longo (INFN Trieste), M. Marisaldi, F. Fuschino, C. Labanti, A. Bulgarelli, F. Gianotti, M. Trifoglio, G. Di Cocco (INAF/IASF Bologna), M. Galli (ENEA), E. Del Monte, I. Donnarumma, Y. Evangelista, M. Feroci, F. Lazzarotto, L. Pacciani, P. Soffitta, E. Costa, I. Lapshov, M. Rapisarda, A. Argan, G. Piano, G. Pucella, S. Sabatini, E. Striani, A. Trois, V. Vittorini (INAF/IASF Roma), A. Chen, S. Mereghetti, P. Caraveo, F. Perotti (INAF/IASF Milano), A. Pellizzoni, M. Pilia (INAF/OA Cagliari), F. D'Ammando, S. Vercellone (INAF/IASF Palermo), G. Barbiellini, E. Moretti, E. Vallazza (INFN Trieste), A. Morselli, P. Picozza (INFN Roma-2), M. Prest (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), P.W. Cattaneo, A. Rappoldi (INFN Pavia), S. Cutini, C. Pittori, F. Verrecchia, P. Santolamazza, F. Lucarelli and P. Giommi (ASDC), L. Salotti (ASI) report: The Gamma-Ray Imaging Detector (GRID) on board AGILE detected the long bright GRB 100724B (Bhat, GCN 10977; Tanaka et al., GCN 10978; Golenetskii et al., GCN 10981, Marisaldi et al., GCN 10994) in the energy range 25 - 500 MeV with a statistical significance larger than 9 sigma. The gamma-ray emission observed by the AGILE-GRID instrument lasted about 100 seconds, and two peaks are evident in the lightcurve consistent with the behaviour reported by Fermi LAT (the MCAL and GRID preliminary lightcurves are available at http://www.asdc.asi.it/images/GRB100724B_lc.gif ). The total fluence above 25 MeV during this time interval is F = 0.2+/-0.1 ph/cm2 . A preliminary estimate of the gamma-ray spectral photon index is alpha= 2.2 +/-0.3. GRB 100724B turns out to be the brightest GRB detected by AGILE above 100 MeV during its operations in space. A plot showing the distance between the GRB position and the AGILE boresight as a function of time can be retrieved at http://www.asdc.asi.it/images/GRB_100724B_distance2.png . This message may be cited.