//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23569 SUBJECT: GRB 181227A: Fermi GBM detection DATE: 18/12/27 22:06:13 GMT FROM: Peter Veres at UAH E. Bissaldi (Politecnico & INFN Bari) and P. Veres (UAH) report on behalf of the Fermi GBM Team: "At 06:17:00.50 UT on 27 December 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 181227A (trigger 567584225 / 181227262). The on-ground calculated location, using the GBM trigger data, is RA, Dec = 24.2, -56.1 (J2000 degrees), with an uncertainty of 1 degree (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32]). The angle from the Fermi LAT boresight at the GBM trigger time is 110 degrees. The GBM light curve consists of two peaks with a duration (T90) of about 13 s (50-300 keV). The time-averaged spectrum from T0-0.3 s to T0+19.8 s is best fit by a Band function with Epeak = 85 +/- 1 keV, alpha = -0.33 +/- 0.02, and beta = -3.08 +/- 0.05. The event fluence (10-1000 keV) in this time interval is (6.85 +/- 0.05)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+8.9 s in the 10-1000 keV band is 110.5 +/- 1.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." [GCN OPS NOTE(27dec18): Per author's request, the alpha value in the third paragraph was changed from "0.33" to "-0.33".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23577 SUBJECT: IPN Triangulation of GRB 181227A (long) DATE: 18/12/28 10:27:23 GMT FROM: Dmitry Svinkin at Ioffe Institute K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova and T. Cline on behalf of the Konus-Wind team, A. Goldstein, M. S. Briggs, and C. Wilson-Hodge 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, S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report: The long-duration GRB 181227A (Fermi-GBM detection: Bissaldi & Veres, GCN Circ. 23569) was detected by Fermi (GBM trigger 567584225), Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), and Swift (BAT) at about 22620 s UT (06:17:00). The burst was detected by Swift (BAT) during the slew and no event data were captured (Sakamoto, Lien, and Pal'shin, priv. comm.). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 29.889 (01h 59m 33s) -53.321 (-53d 19' 14") Corners: 30.664 (02h 02m 39s) -52.621 (-52d 37' 16") 30.861 (02h 03m 27s) -53.105 (-53d 06' 19") 27.501 (01h 50m 00s) -54.693 (-54d 41' 35") 27.344 (01h 49m 22s) -54.208 (-54d 12' 30") --------------------------------------------- The error box area is about 1.13 sq. deg, and its maximum dimension is 2.79 deg (the minimum one is 27.84 arcmin). The Sun distance was about 84 deg. This box may be improved. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB181227_T22619/IPN/ The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23586 SUBJECT: GRB 181227A: Global MASTER Net oprtical inspection DATE: 18/12/29 09:02:21 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, N.Tiurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, D. Vlasenko, D.Kobtsev (Lomonosov Moscow State University, SAI), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar), H. Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio of San Juan National University, Argentina) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), A. Tlatov, V.Senik, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), O. Gress, N.M. Budnev, S. Yazev, O. Chuvalaev (Irkutsk State University, API) V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the FERMI and IPN GRB181227A (E. Bissaldi et al. GCN 23569, Hurley et al 23577 44386 sec after trigger time at 2018-12-27 18:36:46 UT, with upper limit up to 20.4 mag. Observations started at twilight, immediately after sunset. The observations began at zenit distance = 25 deg. The sun altitude is -9.8 deg. MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory) was pointed to the FERMI and IPN GRB181227A 47842 sec after trigger time at 2018-12-27 19:34:23 UT, with upper limit up to 18.0 mag. The observations began at zenit distance = 85 deg. The sun altitude is -17.0 deg. MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) was pointed to the FERMI and IPN GRB181227A 1 days 7760 sec after trigger time at 2018-12-28 08:26:20 UT, with upper limit up to 20.5 mag. Observations started at twilight. The observations began at zenit distance = 83 deg. The sun altitude is -12.7 deg. The galactic latitude b = -60 deg., longitude l = 98 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=894852 No OT found yet. The message may be cited. [GCN OPS NOTE(29dec18): Per author's request, the name of the GRB in the SUBJECT-line was changed from "GRB 181228A" to "GRB 181227A".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23589 SUBJECT: Konus-Wind observation of GRB 181227A DATE: 18/12/29 22:21:42 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report: The long-duration, bright GRB 181227A (Fermi-GBM detection: Bissaldi & Veres, GCN Circ. 23569; IPN triangulation: Hurley et al., GCN Circ. 23577) triggered Konus-Wind at T0=22619.317 s UT (06:16:59.317). The burst light curve shows a single emission episode which starts at ~T0-0.5 s and has a total duration of ~17 s. The emission is seen up to ~10 MeV. As observed by Konus-Wind, the burst had a fluence of 5.91(-0.12,+0.12)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+8.944 s, of 1.39(-0.15,+0.16)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+18.688 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.66(-0.07,+0.07), the high energy photon index beta = -3.53(-0.24,+0.18), the peak energy Ep = 93(-2,+2) keV (chi2 = 72/96 dof). The spectrum near the maximum count rate (measured from T0+8.192 to T0+8.960 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.35(-0.14,+0.15), the high energy photon index beta = -4.34(-5.66,+0.70), the peak energy Ep = 117(-5,+5) keV (chi2 = 31/46 dof). The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB181227_T22619/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23591 SUBJECT: GRB 181227A: CALET Gamma-Ray Burst Monitor detection DATE: 18/12/30 13:26:47 GMT FROM: Valentin Pal'shin at AGU S. Sugita, A. Yoshida, T. Sakamoto, V. Pal'shin (AGU), Y. Kawakubo (LSU), A. Tezuka, S. Matsukawa, H. Onozawa, T. Ito, H. Morita, Y. Sone (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena), and the CALET collaboration: The long soft GRB 181227A (Fermi GBM detection: Bissaldi & Veres, GCN Circ. 23569; IPN Triangulation: Hurley et al., GCN Circ. 23577; Konus-Wind observation: Svinkin et al., GCN Circ. 23589) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 06:17:09.332 UTC on 27 December 2018. Because of a problem in one of the ground alert processing scripts, the GCN notice was not distributed automatically for this event. Since the burst incident direction was at ~110 deg relative to the detector's axes, the signal is barely seen in the HXM detectors, and it was heavily attenuated in the SGM detector. The burst light curve shows a single emission episode which starts at T-9.0 sec and ends at T+7.1 sec. The T90 and the T50 durations measured by the SGM data are 13.9 +- 2.4 sec and 5.9 +- 2.3 sec (40-1000 keV), respectively. The ground processed light curve is available at http://cgbm.calet.jp/cgbm_trigger/ground/1229926558/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.