//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13271 SUBJECT: IPN Triangulation of GRB 120427A DATE: 12/04/28 16:51:31 GMT FROM: Valentin Pal'shin at Ioffe Inst 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, J. Goldsten, on behalf of the MESSENGER GRNS 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, V. Connaughton, M. Briggs, and C. Meegan, on behalf of the Fermi GBM team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and 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, report: The moderately intense single-pulsed GRB 120427A was observed by Fermi (GBM: trigger 357182249), INTEGRAL (SPI-ACS), Konus-Wind, MESSENGER (GRNS), Mars Odyssey (HEND), and Suzaku (WAM) at about 4646 s UT (01:17:26). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 224.935 (14h 59m 44s) +29.311 (+29d 18' 39") Corners: 224.688 (14h 58m 45s) +29.951 (+29d 57' 03") 225.169 (15h 00m 41s) +29.418 (+29d 25' 06") 225.175 (15h 00m 42s) +28.663 (+28d 39' 47") 224.701 (14h 58m 48s) +29.203 (+29d 12' 11") --------------------------------------------- The error box area is 1109 sq. arcmin (0.31 sq. deg), and its maximum dimension is 81 arcmin (the minimum one is 28 arcmin). The Sun distance is ~136 deg. This box may be improved. The time history and spectrum will be given in a forthcoming GCN Circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13272 SUBJECT: Konus-Wind observation of GRB 120427A DATE: 12/04/28 17:04:53 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: GRB 120427A (IPN localization: Hurley at al., GCN 13271) triggered Konus-Wind at T0=04651.927s UT (01:17:31.927) The light curve shows a broad pulse with a total duration of ~5 s. The emission is seen up to ~5 MeV. A spectral lag between the G2(90-300 keV) and the G1(25-90 keV) instrument's light curves is estimated to 0.51 ± 0.07 s (1 sigma). The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB120427_T04651/ As observed by Konus-Wind the burst had a fluence of (7.8 ± 1.1)x10-6 erg/cm2, and a 64-ms peak flux, measured from T0+1.600 s, of (2.6 ± 0.4)x10-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (measured from T0 to T0+8.448 s) is best fitted in the 20 keV - 10 MeV range with the GRB (Band) model, for which: the low-energy photon index alpha = -0.77 (-0.20, +0.23), the high energy photon index beta = -2.9 (-1.1, +0.3), the peak energy Ep = 133(-14, +7) keV, chi2 = 97.5/81 dof. We note a curious resemblance, both in the light curves and in the spectral properties, between GRB 120427A and the one-day older GRB 120426A (Golenetskii et al., GCN 13268). However, a ~126 deg angular distance between their IPN localization boxes (GCN 13265, GCN 13271) leaves no chance for a lensed event. All the quoted results are preliminary. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13274 SUBJECT: GRB 120427A: MASTER follow up observations DATE: 12/04/30 08:14:04 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, A.Kuznetsov, A.Sankovich Moscow Lomonosov State University, Sternberg Astronomical Institute, K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinski, I.Zalozhnich, A. Popov, A. Bourdanov, A. Punanova Ural Federal University Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Kislovodsk was pointed to the GRB120427A 41h 32min after GRB time at 2012-04-28 18:49:09 UT. On our (180s exposure) set robot haven`t found optical transient within IPN Triangulation error-box (Hurley et al., GCN Circ 13271). The 5-sigma upper limit has been about 20.0 mag The message may be cited.