//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26909 SUBJECT: GRB 200128A: Fermi GBM Final Real-time Localization DATE: 20/01/28 03:50:27 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely SHORT GRB At 03:40:05 UT on 28 Jan 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200128A (trigger 601875610.774992 / 200128153). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 158.6, Dec = 41.6 (J2000 degrees, equivalent to J2000 10h 34m, 41d 36'), with a statistical uncertainty of 19.0 degrees. The angle from the Fermi LAT boresight is 129.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200128153/quicklook/glg_skymap_all_bn200128153.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/bn200128153/quicklook/glg_healpix_all_bn200128153.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200128153/quicklook/glg_lc_medres34_bn200128153.gif //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26966 SUBJECT: ZTF Discovery of ZTF20aajnksq: a Rapidly Fading Luminous Transient in the GRB 200128A Localiziation Region DATE: 20/02/02 21:53:10 GMT FROM: Anna Ho at Caltech The Zwicky Transient Facility (ZTF; ATel #11266) reports the discovery of ZTF20aajnksq, a rapidly fading red transient located at 12:47:04.87 +45:12:02.3 (J2000) 191.770292 +45.200626 (J2000) and detected as part of the ZTF Uniform Depth Survey (Goldstein et al. in prep). The source was discovered on UT 2020-01-28T06:43:20.640 at r=19.6 mag, which was 0.74 days after the last non-detection. Follow-up photometry with the IO:O optical imager on the Liverpool Telescope (PI: D. Perley) and the Wafer-Scale Imager for Prime (WASP) on the 200-inch Hale telescope (PI: I. Andreoni) at Palomar Observatory established a rapid fade rate of 2.5 magnitudes in 1.25 days as well as red colors (g-r=+0.65, from the WASP observation). We obtained a target-of-opportunity (PI: M. M. Kasliwal) spectrum with the Low Resolution Imaging Spectrometer (LRIS) on the Keck I 10-m telescope, which showed features consistent with the Lyman break and Lyman alpha absorption at z=2.9. We obtained a target-of-opportunity observation with the Neil Gehrels Swift Observatory (Swift) and detected X-ray emission at 0.0039 ct/s. Assuming a neutral hydrogen column density n_H = 1.77E20/cm2 and a power-law spectrum with photon index 2, the unabsorbed flux is 1.5E-13 erg/cm^2/s, corresponding to a luminosity of 1.1E46 erg/s. We searched the Fermi/GBM catalog and identified a reported likely short GRB 24 degrees away: GRB 200128A (GCN #26909). ZTF20aajnksq is located along the 90% contour of the localization region. The trigger time of GRB 200128A is three hours before the first optical detection. We are grateful to the staff of Palomar and Keck for rapidly scheduling our observations, and to M. Heida (ESO Garching) and J. Rhoads (Goddard) for accommodating the interruption to their scheduled programs. Thank you to the Swift team for rapidly scheduling and executing our observations. ZTF is a project led by PI S. R. Kulkarni at Caltech (see ATEL #11266), and includes IPAC; WIS, Israel; OKC, Sweden; JSI/UMd, USA; UW,USA; DESY, Germany; NRC, Taiwan; UW Milwaukee, USA and LANL USA. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. Alert distribution service provided by DIRAC@UW. Alert filtering is being undertaken by the GROWTH marshal system, supported by NSF PIRE grant 1545949. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 26970 SUBJECT: ZTF20aajnksq: Occulted by Earth at the time of GRB 200128A DATE: 20/02/03 04:40:02 GMT FROM: Rachel Hamburg at UAH R. Hamburg (UAH) reports on behalf of the Fermi-GBM Team: The newly discovered transient ZTF20aajnksq (GCN 26966) was found within the 3-sigma localization contour of GRB 200128A (GCN 26909) approximately 3 hours after the GBM trigger time. However the reported position of ZTF20aajnksq: 12:47:04.87 +45:12:02.3 (J2000) 191.770292 +45.200626 (J2000) was occulted by the Earth for Fermi-GBM from approximately 25.3 minutes prior until 1.8 minutes after the GRB trigger time. The position was also occulted 18.0 minutes prior until 8.8 minutes after the ZTF20aajnksq detection time. Therefore, we consider it unlikely that GRB 200128A is associated with ZTF20aajnksq.