//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11890 SUBJECT: GRB 110406A: An exceptionally bright burst detected by INTEGRAL SPI-ACS DATE: 11/04/06 20:24:50 GMT FROM: Volodymyr Savchenko at ISDC,U of Geneve V. Savchenko, C. Ferrigno, E. Bozzo, M. Nikolajuk, M. Beck (ISDC), S. Mereghetti (INAF/IASF-Milano). V. Beckmann (APC), Arne Rau (MPE), J. Borkowski (CAMK/Torun), D. Götz (CEA/Saclay), and A. von Kienlin (MPE) report on behalf of the INTEGRAL SPI-ACS GRB team: An exceptionally bright burst has been detected by the SPI Anti-Coincidence System (ACS) on-board INTEGRAL at 2011-04-06T03:44:10. The SPI-ACS light curve shows a single smooth peak with a peak count rate of ~19000 counts/50msec of a duration of about 3 seconds. The roughly estimated energy peak flux is of the order of 6e-5 erg/cm2/s. This was one of the brightest bursts ever detected with SPI-ACS. The SPI-ACS light curves are available (both as images and data files) at http://isdc.unige.ch/Soft/ibas/ibas_acs_web.cgi The light curves, binned at 50 ms, are derived from 91 independent detectors with different lower energy thresholds (mainly between 80 keV and 150 keV) and an upper threshold at about 100 MeV. The ACS response varies as a function of the GRB incident angle. For these reasons we caution that the count rates cannot be easily translated into physical flux units. It is not possible to localize a burst based on the SPI-ACS data. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11893 SUBJECT: Konus-Wind observation of GRB 110406A DATE: 11/04/07 13:16:00 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 exceptionally bright GRB 110106A, (Savchenko et al., GCN 11890) triggered Konus-Wind at T0=13446.671s UT (03:44:06.671) The burst light curve consists of a single FRED-like pulse, the total duration of the burst is ~8 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/GRB110406_T13446/ The non-zero spectral lag between the Konus-Wind light curves is evident, the following values are obtained: ------------------------------------------------------------- LC1(keV) LC2(keV) Search interval(s) Scale Lag(ms) ------------------------------------------------------------- G2(70-300) G1(18-70) -0.048:+2.016 16 ms +58 ± 6 G3(300-1160) G1(18-70) -0.016:+1.968 16 ms +127 ± 6 G3(300-1160) G2(70-300) -0.048:+2.016 16 ms +64 ± 5 ------------------------------------------------------------- As observed by Konus-Wind the burst had a fluence of (4.8 ± 0.5)x10-5 erg/cm2, and a 16-ms peak flux, measured from T0+0.160s, of (1.5 ± 0.1)x10-4 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+9.216 s) can be fitted in the 20 keV - 10 MeV range by the GRB (Band) model, for which: the low-energy photon index alpha = -1.24 (-0.07, +0.08), the high energy photon index beta = -2.30 (-0.25, +0.15), the peak energy Ep = 326(-42, +49) keV, chi2 = 117/89 dof. The spectrum at the maximum count rate (measured from T0+0.064 to T0+0.256 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model, for which: the low-energy photon index alpha = -0.61 (-0.13, +0.15), the high energy photon index beta = -2.05 (-0.12, +0.10), the peak energy Ep = 417(-64, +77) keV, chi2 = 56.5/56 dof. All the quoted results are preliminary. The lag errors are given on 1 sigma level. All other quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11900 SUBJECT: IPN triangulation of the bright GRB110406A DATE: 11/04/07 20:48:04 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley on behalf of the Mars Odyssey and MESSENGER GRB teams, I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, D. M. Smith, R. P. Lin, J. McTiernan, R. Schwartz, W. Hajdas, and A. Zehnder, on behalf of the RHESSI GRB team, A. von Kienlin, X. Zhang, and A. Rau, on behalf of the INTEGRAL SPI-ACS GRB team, K. Yamaoka, M. Ohno, Y. Hanabata, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada, T. Murakami, and K. Makishima on behalf of the Suzaku WAM team, S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team, and J. Goldsten, on behalf of the MESSENGER NS GRB team, report: The bright GRB110406A (GCN 11890, 11893), was detected by Mars Odyssey (HEND), MESSENGER (GRNS), Konus-Wind, INTEGRAL SPI-ACS, Suzaku WAM, RHESSI, and Swift BAT (outside the coded field of view). We have triangulated it to a preliminary, 3 sigma confidence error box whose corners are: RA(2000) DEC(2000) 17.008898= 1 h 8 m 2.14 s 36.015742= 36 o 0 ' 56.67 " 16.578396= 1 h 6 m 18.82 s 35.984576= 35 o 59 ' 4.48 " 18.141649= 1 h 12 m 34.00 s 35.601842= 35 o 36 ' 6.63 " 17.702525= 1 h 10 m 48.61 s 35.586179= 35 o 35 ' 10.24 " The best-fit position is RA, Dec= 17.340, +35.809. The error box area is ~600 sq. arcmin. Due to its proximity to the Sun, this position cannot be observed by Swift. This error box can be improved. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11909 SUBJECT: GRB 110406A: Positional coincidence with NGC 404 DATE: 11/04/08 15:43:53 GMT FROM: Antonia Rowlinson at U.of Leicester A. Rowlinson, P.T. O'Brien, N.R. Tanvir (U. Leicester) and A.J. Levan (U. Warwick) report: We note that the the error box of the bright short hard GRB 110406A detected by INTEGRAL SPI-ACS and the IPN (GCNs 11890, 11893, 11900) overlies NGC 404, a dwarf galaxy at a distance of ~3 Mpc. The IPN error box and the extent of NGC 404 are overlayed on a GALEX FUV image here: http://www.star.le.ac.uk/~bar7/NGC404_FUV.jpg NGC 404 is a recently rejuvinated lenticular galaxy, forming the majority of its new stars in a ring with a star formation rate of 2.5e-3 M_sol yr^-1 (Thilker et al., 2010, ApJ, 714, L171). If this GRB is associated with NGC 404, the isotropic energy released would be ~6e46 erg (20 keV - 10 MeV) using the Konus-Wind spectral fit (GCN 11893) which would be consistent with an SGR giant flare origin, while the presence of a young stellar population within this galaxy would also be consistent with this model. For comparison, the giant flare from SGR 1806-20 had Eiso ~3.7e46 erg (Hurley et al., 2005, Nature, 434, 1098).