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A Chromaticity Analysis and PSF Subtraction Techniques for SCExAO/CHARIS Data

Gerard, Benjamin L. and Marois, Christian and Currie, Thayne and Brandt, Timothy and Chilcote, Jeffrey K. and Draper, Zachary H. and Groff, Tyler and Guyon, Olivier and Hayashi, Masahiko and Jovanovic, Nemanja and Knapp, Gillian R. and Kudo, Tomoyuki and Kwon, Jungmi and Lozi, Julien and Martinache, Frantz and McElwain, Michael and Tamura, Motohide and Uyama, Taichi (2019) A Chromaticity Analysis and PSF Subtraction Techniques for SCExAO/CHARIS Data. Astronomical Journal, 158 (1). Art. No. 36. ISSN 1538-3881. doi:10.3847/1538-3881/ab21d4.

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We present an analysis of instrument performance using new observations taken with the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) instrument and the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system. In a correlation analysis of our data sets (which use the broadband mode covering the J band through the K band in a single spectrum), we find that chromaticity in the SCExAO/CHARIS system is generally worse than temporal stability. We also develop a point-spread function (PSF) subtraction pipeline optimized for the CHARIS broadband mode, including a forward modeling-based exoplanet algorithmic throughput correction scheme. We then present contrast curves using this newly developed pipeline. An analogous subtraction of the same data sets using only the H-band slices yields the same final contrasts as the full JHK sequences; this result is consistent with our chromaticity analysis, illustrating that PSF subtraction using spectral differential imaging (SDI) in this broadband mode is generally not more effective than SDI in the individual J, H, or K bands. In the future, the data processing framework and analysis developed in this paper will be important to consider for additional SCExAO/CHARIS broadband observations and other ExAO instruments which plan to implement a similar integral field spectrograph broadband mode.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Gerard, Benjamin L.0000-0003-3978-9195
Marois, Christian0000-0002-4164-4182
Currie, Thayne0000-0002-7405-3119
Brandt, Timothy0000-0003-2630-8073
Chilcote, Jeffrey K.0000-0001-6305-7272
Draper, Zachary H.0000-0002-1834-3496
Groff, Tyler0000-0001-5978-3247
Guyon, Olivier0000-0002-1097-9908
Knapp, Gillian R.0000-0002-9259-1164
Kudo, Tomoyuki0000-0002-9294-1793
Kwon, Jungmi0000-0003-2815-7774
Lozi, Julien0000-0002-3047-1845
Martinache, Frantz0000-0003-1180-4138
McElwain, Michael0000-0003-0241-8956
Tamura, Motohide0000-0002-6510-0681
Uyama, Taichi0000-0002-6879-3030
Additional Information:© 2019 The American Astronomical Society. Received 2019 February 18; revised 2019 May 9; accepted 2019 May 14; published 2019 July 1. The data in this paper was obtained through 2017B open use Canadian and US Gemini exchange time (Gerard 2017). We gratefully acknowledge research support of the Natural Sciences and Engineering Council of Canada through the Postgraduate Scholarships-Doctoral discovery grant (DG), and Technologies for Exo-Planetary Science Collaborative Research and Training Experience programs. The development of SCExAO was supported by the JSPS (Grant-in-Aid for Research #23340051, #26220704 #23103002), the Astrobiology Center of the National Institutes of Natural Sciences, Japan, the Mt. Cuba Foundation and the directors contingency fund at Subaru Telescope. CHARIS was built at Princeton University under a Grant-in-Aid for Scientific Research on Innovative Areas from MEXT of the Japanese government (# 23103002). We thank Jason Wang and Jean-Baptiste Ruffio for helpful discussions and suggestions about forward modeling. The authors thank the anonymous referee for the comments and suggestions that have significantly improved this manuscript. The authors acknowledge and support the cultural and spiritual importance of the summit of Maunakea to the Hawaiian native community. We are grateful to share and respect this land with the community.
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Japan Society for the Promotion of Science (JSPS)23340051
Japan Society for the Promotion of Science (JSPS)26220704
Japan Society for the Promotion of Science (JSPS)23103002
National Institutes of Natural Sciences of JapanUNSPECIFIED
Mt. Cuba FoundationUNSPECIFIED
Subaru TelescopeUNSPECIFIED
Subject Keywords:planets and satellites: general – techniques: high angular resolution – techniques: image processing
Issue or Number:1
Record Number:CaltechAUTHORS:20190710-080727517
Persistent URL:
Official Citation:Benjamin L. Gerard et al 2019 AJ 158 36
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97022
Deposited By: Tony Diaz
Deposited On:10 Jul 2019 16:59
Last Modified:16 Nov 2021 17:25

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