SIOUX project: a simultaneous multiband camera for exoplanet atmospheres studies

Abstract

The exoplanet revolution is well underway. The last decade has seen order-of-magnitude increases in the number of known planets beyond the Solar system. Detailed characterization of exoplanetary atmospheres provide the best means for distinguishing the makeup of their outer layers, and the only hope for understanding the interplay between initial composition chemistry, temperature-pressure atmospheric profiles, dynamics and circulation.While pioneering work on the observational side has produced the first important detections of atmospheric molecules for the class of transiting exoplanets, important limitations are still present due to the lack of systematic, repeated measurements with optimized instrumentation at both visible (VIS) and near-infrared (NIR) wavelengths. It is thus of fundamental importance to explore quantitatively possible avenues for improvements. In this paper we report initial results of a feasibility study for the prototype of a versatile multi-band imaging system for very high-precision differential photometry that exploits the choice of specifically selected narrow-band filters and novel ideas for the execution of simultaneous VIS and NIR measurements.Starting from the fundamental system requirements driven by the science case at hand, we describe a set of three opto-mechanical solutions for the instrument prototype: 1) a radial distribution of the optical flux using dichroic filters for the wavelength separation and narrow-band filters or liquid crystal filters for the observations; 2) a tree distribution of the optical flux (implying 2 separate foci), with the same technique used for the beam separation and filtering; 3) an 'exotic' solution consisting of the study of a complete optical system (i.e. a brand new telescope) that exploits the chromatic errors of a reflecting surface for directing the different wavelengths at different foci.In this paper we present the first results of the study phase for the three solutions, as well as the results of two laboratory prototypes (related to the first two options), that simulate the most critical aspects of the future instrument.

The Oxyometer: A Novel Instrument Concept for Characterizing Exoplanet Atmospheres

“…In this case the bandpass is blueshifted as the angle of incidence of the incoming light is tilted away from normal incidence. Some consideration has been given to utilizing this technology for an instrument with the goal of achieving photon-limited, ultra-narrow-band photometry (Colón et al 2010;Sing et al 2011b;Christille et al 2016). However, no instruments have been developed that achieve the simultaneous observation of a star through two bandpasses that have <1 nm full width at half maximum (FWHM).…”

The Benefit of Simultaneous Seven-filter Imaging: 10 Years of GROND Observations

“…GROND-inspired instruments include the 6-channel RATIR (Butler et al 2012) and the 4-channel ROS2 (Spano et al 2010) instruments. Further projects for simultaneous multi-band instruments are the 8-channel OCTOCAM (Gorosabel & Ugarte Postigo 2010), selected as part of the Gemini instrumentation program in 2017 (Roming et al 2018), the 4-channel SPARC4 (Rodrigues et al 2012) planned for installation at the 1.6 m telescope of the Pico dos Dias Observatory (Brazil) (Bernardes et al 2018), an unnamed 8-channel imager for the IRTF (Connelley et al 2013), and the SIOUX project (Christille et al 2016). In comparison, the GROND instrument (Greiner et al 2008) at the 2.2 m telescope of the Max-Planck Society (MPG) in La Silla (ESO/Chile) with its 7 simultaneous channels so far still delivers the largest degree of multiplexing at such a telescope size.…”