The Asteroid Terrestrial impact Last Alert System (ATLAS) system consists of two 0.5 m Schmidt telescopes with cameras covering 29 square degrees at plate scale of 1.86 arcsec per pixel. Working in tandem, the telescopes routinely survey the whole sky visible from Hawaii (above delta > -50 degrees) every two nights, exposing four times per night, typically reaching o < 19 magnitude per exposure when the moon is illuminated and c < 19.5 magnitude per exposure in dark skies. Construction is underway of two further units to be sited in Chile and South Africa which will result in an all-sky daily cadence from 2021. Initially designed for detecting potentially hazardous near earth objects, the ATLAS data enable a range of astrophysical time domain science. To extract transients from the data stream requires a computing system to process the data, assimilate detections in time and space and associate them with known astrophysical sources. Here we describe the hardware and software infrastructure to produce a stream of clean, real, astrophysical transients in real time. This involves machine learning and boosted decision tree algorithms to identify extragalactic and Galactic transients. Typically we detect 10-15 supernova candidates per night which we immediately announce publicly. The ATLAS discoveries not only enable rapid follow-up of interesting sources but will provide complete statistical samples within the local volume of 100 Mpc. A simple comparison of the detected supernova rate within 100 Mpc, with no corrections for completeness, is already significantly higher (factor 1.5 to 2) than the current accepted rates. ; National Aeronautics & Space Administration (NASA) NN12AR55G 80NSSC18K0284 80NSSC18K1575 EU FP7/2007-2013 ERC 291222 STFC Grants ST/P000312/1 ST/N002520/1 ST/S006109/1 QUB Kelvin HPC cluster QUB International Engagement Fund European Union (EU) 842471
Despite vast improvements in the measurement of the cosmological parameters, the nature of dark energy and an accurate value of the Hubble constant (H-0) in the Hubble-Lemaitre law remain unknown. To break the current impasse, it is necessary to develop as many independent techniques as possible, such as the use of Type II supernovae (SNe II). The goal of this paper is to demonstrate the utility of SNe II for deriving accurate extragalactic distances, which will be an asset for the next generation of telescopes where more-distant SNe II will be discovered. More specifically, we present a sample from the Dark Energy Survey Supernova Program (DES-SN) consisting of 15 SNe II with photometric and spectroscopic information spanning a redshift range up to 0.35. Combining our DES SNe with publicly available samples, and using the standard candle method (SCM), we construct the largest available Hubble diagram with SNe II in the Hubble flow (70 SNe II) and find an observed dispersion of 0.27 mag. We demonstrate that adding a colour term to the SN II standardization does not reduce the scatter in the Hubble diagram. Although SNe II are viable as distance indicators, this work points out important issues for improving their utility as independent extragalactic beacons: find new correlations, define a more standard subclass of SNe II, construct new SN II templates, and dedicate more observing time to high-redshift SNe II. Finally, for the first time, we perform simulations to estimate the redshift-dependent distance-modulus bias due to selection effects. ; National Science Foundation (NSF) AST-1211916 TABASGO Foundation, Gary and Cynthia Bengier Christopher R. Redlich Fund Sylvia and Jim Katzman Foundation Miller Institute for Basic Research in Science (UC Berkeley) - European Union 839090 Spanish grant PGC2018-095317-B-C21 European Union (EU) EU/FP7-ERC grant 615929 National Science Foundation (NSF) Hyper Suprime-Cam (HSC) collaboration includes the astronomical communities of Japan Princeton University Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) University of Tokyo High Energy Accelerator Research Organization (KEK) FIRST programme from the Japanese Cabinet Office Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science Japan Science & Technology Agency (JST) Toray Industries, Inc. Institute for Astronomy (the University of Hawaii) Max Planck Society Foundation CELLEX National Central University of Taiwan Space Telescope Science Institute National Aeronautics & Space Administration (NASA) NNX08AR22G National Aeronautics & Space Administration (NASA) National Science Foundation (NSF) AST-1238877 University of Maryland Eotvos Lorand University (ELTE) National Aeronautics & Space Administration (NASA) W.M. Keck Foundation National Research Council of Canada Centre National de la Recherche Scientifique (CNRS) Science & Technology Facilities Council (STFC) National Research Council Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) Australian Research Council National Council for Scientific and Technological Development (CNPq) Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) GN-2005A-Q11 GN-2005B-Q-7 GN-2006A-Q-7 GS-2005A-Q-11 GS-2005BQ-6 GS-2008B-Q-56 United States Department of Energy (DOE) Spanish Government Science & Technology Facilities Council (STFC) Higher Education Funding Council for England National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign Ohio State University Mitchell Institute for Fundamental Physics and Astronomy at Texas AM University Ciencia Tecnologia e Inovacao (FINEP) Fundacao Carlos Chagas Filho de Amparo Conselho Nacional de Desenvolvimento Cient'tronomy at Texas AM University German Research Foundation (DFG) University of Portsmouth OzDES Membership Consortium National Science Foundation (NSF) AST-1138766 AST-1536171 AYA2015-71825 ESP2015-66861 FPA2015-68048 SEV2016-0588 SEV-2016-0597 European Union (EU) European Union - CERCA programme of the Generalitat de Catalunya European Research Council (ERC) European Research Council (ERC) 240672 291329 306478 National Council for Scientific and Technological Development (CNPq) 465376/2014-2 United States Department of Energy (DOE) United States Department of Energy (DOE) DE-AC02-05CH11231 United States Department of Energy (DOE) DE-AC02-05CH11231