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

We present an analysis of instrument performance using new observations taken with the CoronagraphicHigh Angular ResolutionImaging Spectrograph(CHARIS) instrument and the Subaru CoronagraphicExtreme Adaptive Optics (SCExAO) system. In a correlation analysis of our data sets (which use the broadbandmode covering the J band through the K bandin 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) subtractionpipeline optimized for the CHARIS broadbandmode, including a forward modeling-based exoplanetalgorithmic throughput correction scheme. We then present contrast curves using this newly developed pipeline. An analogous subtractionof the same data sets using only the H-bandslices yields the same final contrasts as the full JHK sequences; this result is consistent with our chromaticity analysis, illustrating that PSF subtractionusing spectral differential imaging (SDI) in this broadbandmode 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 broadbandobservations and other ExAO instruments which plan to implement a similar integral field spectrograph broadbandmode.