A Chromaticity Analysis and PSF Subtraction Techniques for SCExAO/CHARIS data. (arXiv:1905.05821v1 [astro-ph.EP])

A Chromaticity Analysis and PSF Subtraction Techniques for SCExAO/CHARIS data. (arXiv:1905.05821v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Gerard_B/0/1/0/all/0/1">Benjamin L. Gerard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marois_C/0/1/0/all/0/1">Christian Marois</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Currie_T/0/1/0/all/0/1">Thayne Currie</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brandt_T/0/1/0/all/0/1">Timothy D. Brandt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chilcote_J/0/1/0/all/0/1">Jeffrey K. Chilcote</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Draper_Z/0/1/0/all/0/1">Zachary H. Draper</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Groff_T/0/1/0/all/0/1">Tyler Groff</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guyon_O/0/1/0/all/0/1">Olivier Guyon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hayashi_M/0/1/0/all/0/1">Masahiko Hayashi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jovanovic_N/0/1/0/all/0/1">Nemanja Jovanovic</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Knapp_G/0/1/0/all/0/1">Gillian R. Knapp</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kudo_T/0/1/0/all/0/1">Tomoyuki Kudo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kwon_J/0/1/0/all/0/1">Jungmi Kwon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lozi_J/0/1/0/all/0/1">Julien Lozi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martinache_F/0/1/0/all/0/1">Frantz Martinache</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McElwain_M/0/1/0/all/0/1">Michael W. McElwain</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tamura_M/0/1/0/all/0/1">Motohide Tamura</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Uyama_T/0/1/0/all/0/1">Taichi Uyama</a>

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 datasets (which use the broadband mode
covering J through 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 modelling-based exoplanet
algorithmic throughput correction scheme. We then present contrast curves using
this newly developed pipeline. An analogous subtraction of the same datasets
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.

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 datasets (which use the broadband mode
covering J through 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 modelling-based exoplanet
algorithmic throughput correction scheme. We then present contrast curves using
this newly developed pipeline. An analogous subtraction of the same datasets
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.

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