//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26600 SUBJECT: Swift GRB191228.00: Global MASTER-Net observations report DATE: 19/12/28 00:10:10 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), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), 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) was pointed to the Swift GRB191228.00 (trigger No 946476,00h 21m 21.36s , -08d 40m 12.0s, R=0.05) errorbox 146 sec after trigger time at 2019-12-28 00:03:46 UT, with upper limit up to 17.3 mag. The observations began at zenith distance = 82 deg. The sun altitude is -75.7 deg. The galactic latitude b = -70 deg., longitude l = 102 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1241866 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 157 | MASTER-IAC | P| | 20 | 16.9 | 208 | MASTER-IAC | P| | 40 | 17.3 | 265 | MASTER-IAC | P| | 50 | 17.3 | The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26601 SUBJECT: GRB 191228A: Swift detection of a burst DATE: 19/12/28 00:18:33 GMT FROM: Scott Barthelmy at NASA/GSFC M. G. Bernardini (INAF-OAB), S. D. Barthelmy (GSFC), P. D'Avanzo (INAF-OAB), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), S Laha (GSFC/UMBC/CRESST), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), M. J. Moss (GWU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team: At 00:01:19 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 191228A (trigger=946476). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 5.339, -8.670, which is RA(J2000) = 00h 21m 21s Dec(J2000) = -08d 40' 12" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve is typically plain for an image trigger. The XRT began observing the field at 00:03:23.2 UT, 123.4 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 5.34755, -8.68313 which is equivalent to: RA(J2000) = 00h 21m 23.41s Dec(J2000) = -08d 40' 59.3" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 56 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (3.80 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.4 (+5.17/-3.93) x 10^21 cm^-2 (90% confidence). The initial flux in the 0.1 s image was 1.26e-08 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 131 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04. Burst Advocate for this burst is M. G. Bernardini (grazia.bernardini AT brera.inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26603 SUBJECT: GRB 191228A: UKIRT NIR upper limit DATE: 19/12/28 07:36:11 GMT FROM: Dong Xu at NAOC/CAS D. Xu, Z.P. Zhu, B.Y. Yu, H.J. Wang, L. Ge (NAOC) report: We observed the field of GRB 191228A (Bernardini et al., GCN 26601) using the 3.8-m United Kingdom Infra-Red Telescope (UKIRT). Observations started at 04:38:02 UT on 2019-12-28 (i.e., 4.612 hr after the BAT trigger), and 3600 s H-band imagining was obtained in a seeing of ~1.0". No NIR afterglow is detected in the stacked image at the XRT position (Bernardini et al., GCN 26601), down to a limiting magnitude of H ~ 20.1, calibrated with nearby 2MASS stars. We thank the great support of the UKIRT staff/observer, in particular Michael Pohlen and Watson Varricatt. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26604 SUBJECT: GRB 191228A: ePESSTO+ NTT optical upper limit DATE: 19/12/28 10:11:51 GMT FROM: Daniele B Malesani at DTU Space Tomas Mueller (Southampton), Juanita Antilen (Universidad de Chile), Daniele B. Malesani (DTU Space), Paolo D'Avanzo (INAF/Brera), Joe Anderson (ESO), Mariusz Gromadzki (Warsaw), Cosimo Inserra (Cardiff), Erkki Kankare (Turku), Matt Nicholl (Birmingham), Ofer Yaron (Weizmann), David Young (QUB), Roberta Carini (INAF/Roma), Regis Cartier (CTIO), Ting-Wan Chen (Stockholm), Matt Grayling, Mat Smith, Phil Wiseman (Southampton), Chris Frohmaier (ICG Portsmouth), report: We observed GRB 191228A (Bernardini et al., GCN 26601) under the the extended Public ESO Spectroscopic Survey for Transient Objects (ePESSTO+; see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org ). The observations were performed on the ESO New Technology Telescope at La Silla with the EFOSC2 instrument in imaging mode, starting on 2019 Dec 28 at 01:22:23 UT (i.e. 1.35 hr after the burst). In a 2-minute image taken using the r filter, we detect no objects consistent with the XRT position, down to a 3-sigma limiting magnitude of r = 22.6 AB (calibrated against stars from the Pan-STARRS catalog). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26606 SUBJECT: GRB 191228A: Enhanced Swift-XRT position DATE: 19/12/28 17:21:03 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 2775 s of XRT Photon Counting mode data and 5 UVOT images for GRB 191228A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 5.34686, -8.68275 which is equivalent to: RA (J2000): 00h 21m 23.25s Dec (J2000): -08d 40' 57.9" with an uncertainty of 1.4 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26607 SUBJECT: GRB 191228A: Swift-BAT refined analysis DATE: 19/12/28 17:38:12 GMT FROM: Scott Barthelmy at NASA/GSFC T. N. Ukwatta (LANL) S. D. Barthelmy (GSFC), M. G. Bernardini (INAF-OAB), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlinks, we report further analysis of BAT GRB 191228A (trigger #946476) (Bernardini, et al., GCN Circ. 26601). The BAT ground-calculated position is RA, Dec = 5.341, -8.650 deg, which is RA(J2000) = 00h 21m 21.9s Dec(J2000) = -08d 38' 58.3" with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 90%. The mask-weighted light curve] shows 3 broad peaks starting at T-50 sec with peaks at ~T+5, ~T+55, and ~T+130 sec, and ending at T+190 sec. T90 (15-350 keV) is 166.9 +- 10.2 sec (estimated error including systematics). The time-averaged spectrum from T-39.2 to T+138.9 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.06 +- 0.14. The fluence in the 15-150 keV band is 2.0 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+54.59 sec in the 15-150 keV band is 0.6 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/946476/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26609 SUBJECT: GRB 191228A: Swift-XRT refined Analysis DATE: 19/12/28 19:22:36 GMT FROM: Phil Evans at U of Leicester J. D. Gropp (PSU), A. Tohuvavohu (U. Toronto), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA) and M.G. Bernardini report on behalf of the Swift-XRT team: We have analysed 7.7 ks of XRT data for GRB 191228A (Bernardini et al. GCN Circ. 26601), from 127 s to 48.0 ks after the BAT trigger. The data comprise 216 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 26606). The late-time light curve (from T0+5.4 ks) can be modelled with a power-law decay with a decay index of alpha=1.58 (+0.13, -0.12). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.96 (+/-0.05). The best-fitting absorption column is 3.09 (+0.24, -0.23) x 10^21 cm^-2, in excess of the Galactic value of 3.8 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.14 (+0.16, -0.15) and a best-fitting absorption column of 4.0 (+/-0.7) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (6.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 4.0 (+/-0.7) x 10^21 cm^-2 Galactic foreground: 3.8 x 10^20 cm^-2 Excess significance: 8.7 sigma Photon index: 2.14 (+0.16, -0.15) If the light curve continues to decay with a power-law decay index of 1.58, the count rate at T+24 hours will be 8.1 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.9 x 10^-13 (5.0 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00946476. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26611 SUBJECT: GRB 191228A: Swift/UVOT Upper Limits DATE: 19/12/29 21:38:22 GMT FROM: Sam LaPorte at PSU GRB 191228A: Swift/UVOT Upper Limits J. D. Gropp (PSU) and M. G. Bernardini (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 191228A 131 s after the BAT trigger (Bernardini et al., GCN Circ. 26601). No optical afterglow consistent with the XRT position (Bernardini et al. GCN Circ. 26601) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 131 281 147 >20.3 u_FC 289 539 246 >19.6 white 131 1009 327 >20.6 v 619 811 39 >18.2 b 545 737 39 >19.2 u 289 712 265 >19.6 w1 668 860 39 >18.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26615 SUBJECT: GRB 191228A: Mondy optical upper limit DATE: 19/12/30 15:53:01 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE), K. Kamyshnikov (HSE), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We observed the field of GRB 191228A (Bernardini et al. GCN 26601) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Dec. 28 (UT) 11:15:09. We do not detect any optical object in the Enhanced Swift-XRT position (Evans et al. GCN 26606). Preliminary photometry of the field is following. Date UT start t-T0 Filter Exp. OT UL(3sigma) (mid, days) (s) 2019-12-28 11:15:09 0.48923 R 30*120 n/d 20.1 Photometry is based on the USNO-B2.0 nearby stars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26630 SUBJECT: GRB 191228A: Early Optical Upper Limits from LCO DATE: 20/01/02 12:22:34 GMT FROM: Robert Strausbaugh at U. of the Virgin Islands R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration: We observed Swift GRB 191228A (Barthelmy et al., GCN 26601) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on December 28, from 00:59 to 01:31 UT (corresponding to 0.66 to 1.22 hours from the GRB trigger time) with Bessel R and I filters. We performed a series of 5x180s exposures in both bands. We do not detect any sources in the individual frames (nor in 5 stacked images in each band) in the enhanced Swift error region (Barthelmy et al., GCN 26607). Using the USNO-B.1 catalog as reference, we obtain the following 3-sigma upper limits: R > 14.69 I > 14.79 The low limiting magnitudes are most likely due to high sky background in the images in both bands. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26653 SUBJECT: GRB 191228A: FRAM-ORM optical limit DATE: 20/01/07 11:00:43 GMT FROM: Martin Jelinek at Astro.Inst-AVCR,Ondrejov Martin Jelinek (ASU CAS Ondrejov, CZ), Sergey Karpov, Martin Masek, Petr Janecek, Jakub Jurysek, Jan Ebr, Ronan Cunniffe, Petr Travnicek, Michael Prouza (Institute of Physics, Prague, CZ) and Jan Strobl (ASU CAS Ondrejov, CZ) report: The 25cm robotic telescope FRAM-CTA at La Palma (Spain) reacted robotically under inferior weather conditions to the alert of GRB 191228A (Bernardini et al., GCN Circular 26601) and obtained a set of 20s unfiltered images starting at 00:03:11.1 UT, i.e. 112s after the initial BAT trigger. We do not detect any new source in comparison to USNO-B1.0 catalog neither in single images nor in a combined 20x20s frame (mean exp time 363s post trigger, 3-sigma limit R>~17.7).