//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29081 SUBJECT: GRB 201218A: Fermi GBM Final Real-time Localization DATE: 20/12/18 04:24:37 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 04:14:15 UT on 18 Dec 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 201218A (trigger 629957660.899176 / 201218177). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 286.9, Dec = 24.2 (J2000 degrees, equivalent to J2000 19h 07m, 24d 11'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 95.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201218177/quicklook/glg_skymap_all_bn201218177.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201218177/quicklook/glg_healpix_all_bn201218177.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201218177/quicklook/glg_lc_medres34_bn201218177.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29083 SUBJECT: GRB 201218A: BALROG localization (Fermi Trigger 629957660 / GRB 201218177) DATE: 20/12/18 04:43:49 GMT FROM: Jochen Greiner at MPE,Garching B. Biltzinger, F. Kunzweiler, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 629957660 at 04:14:15 on 18 Dec. 2020 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position (1 sigma statistical errors) is: RA(2000.0) = 287.38+/-0.29 deg Decl.(2000.0) = 26.80+/-0.30 deg We estimate an additional systematic error of 1 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB201218177/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB201218177/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB201218177/json //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29087 SUBJECT: Fermi GRB 201218A: Global MASTER-Net observations report DATE: 20/12/18 19:15:25 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 201218A ( Fermi GBM team, GCN 29081) errorbox 53279 sec after notice time and 53345 sec after trigger time at 2020-12-18 19:03:21 UT, with upper limit up to 16.5 mag. Observations started at twilight. The observations began at zenith distance = 64 deg. The sun altitude is -11.5 deg. The galactic latitude b = 7 deg., longitude l = 57 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1505659 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 22028 | 2020-12-18 10:20:53 | MASTER- | (19h 12m 49.70s , +21d 30m 56.1s) | C | 60 | 15.4 | 23215 | 2020-12-18 10:40:41 | MASTER- | (19h 12m 56.18s , +21d 28m 59.3s) | C | 60 | 13.0 | 53435 | 2020-12-18 19:03:21 | MASTER-IAC | (19h 01m 57.16s , +23d 55m 31.2s) | C | 180 | 16.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29090 SUBJECT: IPN triangulation of GRB 201218A DATE: 20/12/19 01:12:10 GMT FROM: Dmitry Svinkin at Ioffe Institute K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Ridnaia, and T. Cline on behalf of the Konus-Wind 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, very bright GRB 201218A (Fermi-GBM detection: The Fermi GBM team, GCN Circ. 29081; BALROG localization: Biltzinger et al., GCN Circ. 29083) has been detected by Fermi (GBM trigger 629957660), Konus-Wind, Mars-Odyssey (HEND), and Swift (BAT), so far, at about 15256 s UT (04:14:16). The burst was outside the coded field of view of the BAT. We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 288.498 (19h 13m 59s) +28.356 (+28d 21' 23") Corners: 288.470 (19h 13m 53s) +28.144 (+28d 08' 38") 288.400 (19h 13m 36s) +28.556 (+28d 33' 23") 288.526 (19h 14m 06s) +28.569 (+28d 34' 08") 288.596 (19h 14m 23s) +28.156 (+28d 09' 22") --------------------------------------------- The error box area is 168 sq. arcmin, and its maximum dimension is 26 arcmin (the minimum one is 6.7 arcmin). The Sun distance was 56 deg. The IPN localization is consistent with, but reduces the area of, the Fermi RoboBA and BALROG localizations (GCN Circ. 29081 and 29083). A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB201218_T15255/IPN/ The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29095 SUBJECT: Konus-Wind observation of GRB 201218A DATE: 20/12/20 14:24:35 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, report: The long-duration, very bright GRB 201218A (Fermi-GBM detection: The Fermi GBM team, GCN Circ. 29081; BALROG localization: Biltzinger et al., GCN Circ. 29083; IPN triangulation: Hurley et al., GCN Circ. 29090) triggered Konus-Wind at T0=15253.184 s UT (04:14:13.184). The burst light curve shows a multipeaked structure which starts at ~T0-17 s and has a total duration of ~55 s, followed by a weak tail seen up to ~T0+120 s. The emission is seen up to ~5 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB201218_T15255 As observed by Konus-Wind, the burst had a fluence of 1.35(-0.07,+0.07)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+8.544 s, of 2.23(-0.28,+0.29)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+20.736 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 = -0.82(-0.03,+0.03), the high energy photon index beta = -3.00(-0.50,+0.27), the peak energy Ep = 472(-24,+23) keV (chi2 = 139/97 dof). The spectrum near the maximum count rate (measured from T0+8.192 to T0+8.704 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.72(-0.09,+0.09) and Ep = 605(-68,+80) keV (chi2 = 51/63 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.5 (chi2 = 50/62 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.