MIRC-X: A Highly Sensitive Six-telescope Interferometric Imager at the CHARA Array

Narsireddy Anugu , Jean-Baptiste Le Bouquin (1) , John D. Monnier , Stefan Kraus , Benjamin R. Setterholm , Aaron Labdon , Claire L. Davies , Cyprien Lanthermann (1) , Tyler Gardner , Jacob Ennis , Keith J. C. Johnson , Theo ten Brummelaar , Gail Schaefer , Judit Sturmann

1 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble

Michigan InfraRed Combiner-eXeter (MIRC-X) is a new highly sensitive six-telescope interferometric imager installed at the CHARA Array that provides an angular resolution equivalent of up to a 330 m diameter baseline telescope in J- and H-band wavelengths ( $\tfrac{\lambda }{2B}\sim 0.6$ mas). We upgraded the original Michigan InfraRed Combiner (MIRC) instrument to improve sensitivity and wavelength coverage in two phases. First, a revolutionary sub-electron noise and fast-frame-rate C-RED ONE camera based on an SAPHIRA detector was installed. Second, a new-generation beam combiner was designed and commissioned to (i) maximize sensitivity, (ii) extend the wavelength coverage to J band, and (iii) enable polarization observations. A low-latency and fast-frame-rate control software enables high-efficiency observations and fringe tracking for the forthcoming instruments of the CHARA Array. Since mid-2017, MIRC-X has been offered to the community and has demonstrated best-case H-band sensitivity down to 8.2 correlated magnitude. MIRC-X uses single-mode fibers to coherently combine the light from six telescopes simultaneously with an image-plane combination scheme and delivers a visibility precision better than 1%, and closure phase precision better than 1°. MIRC-X aims at (i) imaging protoplanetary disks, (ii) detecting exoplanets with precise astrometry, and (iii) imaging stellar surfaces and starspots at an unprecedented angular resolution in the near-infrared. In this paper, we present the instrument design, installation, operation, and on-sky results, and demonstrate the imaging capability of MIRC-X on the binary system ι Peg. The purpose of this paper is to provide a solid reference for studies based on MIRC-X data and to inspire future instruments in optical interferometry.

Mots clés: Very long baseline interferometry; Michelson interferometry; Astronomical detectors; Binary stars; Astronomy data reduction; Astronomical instrumentation; Astronomy data acquisition; Interferometers; Young stellar objects; Exoplanet detection methods; Starspots; Astronomy data analysis; 1769; 1045; 84; 154; 1861; 799; 1860; 805; 1834; 489; 1572; 1858; Astrophysics - Instrumentation and Methods for Astrophysics; Astrophysics - Solar and Stellar Astrophysics

Domaines: Planète et Univers [physics]

Narsireddy Anugu, Jean-Baptiste Le Bouquin, John D. Monnier, Stefan Kraus, Benjamin R. Setterholm, et al.. MIRC-X: A Highly Sensitive Six-telescope Interferometric Imager at the CHARA Array. The Astronomical Journal, 2020, 160, ⟨10.3847/1538-3881/aba957⟩. ⟨insu-03705176⟩