posted on 2020-11-06, 16:01authored byA Chaushev, L Raynard, MR Goad, P Eigmüller, DJ Armstrong, JT Briegal, MR Burleigh, SL Casewell, S Gill, JS Jenkins, LD Nielsen, CA Watson, RG West, PJ Wheatley, S Udry, JI Vines
Vetting of exoplanet candidates in transit surveys is a manual process, which suffers from a large number of false positives and a lack of consistency. Previous work has shown that convolutional neural networks (CNN) provide an efficient solution to these problems. Here, we apply a CNN to classify planet candidates from the Next Generation Transit Survey (NGTS). For training data sets we compare both real data with injected planetary transits and fully simulated data, as well as how their different compositions affect network performance. We show that fewer hand labelled light curves can be utilized, while still achieving competitive results. With our best model, we achieve an area under the curve (AUC) score of (95.6±0.2) per cent and an accuracy of (88.5±0.3) per cent on our unseen test data, as well as (76.5±0.4) per cent and (74.6±1.1) per cent in comparison to our existing manual classifications. The neural network recovers 13 out of 14 confirmed planets observed by NGTS, with high probability. We use simulated data to show that the overall network performance is resilient to mislabelling of the training data set, a problem that might arise due to unidentified, low signal-to-noise transits. Using a CNN, the time required for vetting can be reduced by half, while still recovering the vast majority of manually flagged candidates. In addition, we identify many new candidates with high probabilities which were not flagged by human vetters.
Funding
Based on data collected under the NGTS project at the
ESO La Silla Paranal Observatory. The NGTS facility is
operated by the consortium institutes with support from
the UK Science and Technology Facilities Council (STFC)
through projects ST/M001962/1 and ST/S002642/1. LR is supported by an STFC studentship (1795021). The
contributions at the University of Leicester by MRG and
MRB have been supported by STFC through consolidated
grant ST/N000757/1. PE and ACh acknowledge the support of the DFG priority program SPP 1992 ”Exploring
the Diversity of Extrasolar Planets” (RA 714/13-1). The
contributions at the University of Warwick by PJW and
RGW have been supported by STFC through consolidated
grants ST/L000733/1 and ST/P000495/1. DJA gratefully
acknowledges support from the STFC via an Ernest
Rutherford Fellowship (ST/R00384X/1). JSJ acknowledges
support by Fondecyt grant 1161218 and partial support by
CATA-Basal (PB06, CONICYT). This work has made use
of data from the European Space Agency (ESA) mission
Gaia (https://www.cosmos.esa.int/gaia), processed by the
Gaia Data Processing and Analysis Consortium (DPAC,
https://www.cosmos.esa.int/web/gaia/dpac/consortium).
Funding for the DPAC has been provided by national
institutions, in particular the institutions participating in
the Gaia Multilateral Agreement. This research has made
use of the NASA Exoplanet Archive, which is operated by
the California Institute of Technology, under contract with
the National Aeronautics and Space Administration under
the Exoplanet Exploration Program. This research used
the ALICE High Performance Computing Facility at the
University of Leicester.
History
Citation
Monthly Notices of the Royal Astronomical Society, Volume 488, Issue 4, October 2019, Pages 5232–5250, https://doi.org/10.1093/mnras/stz2058
Author affiliation
/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy
Version
VoR (Version of Record)
Published in
Monthly Notices of the Royal Astronomical Society
Volume
488
Issue
4
Pagination
5232-5250
Publisher
Oxford University Press (OUP), Royal Astronomical Society
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