The upgraded MIRC-X beam combiner at the CHARA array combines the light from all six telescopes simultaneously. It disperses light across several spectral channels and operates in the near infrared J and H-bands. The low-resolution H-band mode (R=50) is fully commissioned. MIRC-X can be used to create images of stellar surfaces. The precision closure phases are well suited to detecting faint binary companions.
The original Michigan Infrared Beam Combiner (MIRC) was developed by John Monnier and his optical interferometry group in the Astronomy Department at the University of Michigan. It dispersed light across 8 spectral channels in the near infrared H-band (1.6 microns). MIRC produced the first images of a main sequence star other than the sun, measured the oblateness and gravity darkening of rapid rotators, imaged starpots on the surface of magnetically active stars, and detected faint binary companions at small separations.
MIRC-X is a new beam combination instrument at the CHARA array that enables 6-telescope interferometric imaging on object classes that until now have been out of reach for milliarcsecond-resolution imaging. As part of an instrumentation effort lead by the University of Exeter and University of Michigan, we equipped the MIRC instrument with an ultra-low read-noise detector system and extended the wavelength range to the J and H-band. The first phase of the MIRC-X commissioning was successfully completed in June 2017.
The Michigan Infrared Combiner (MIRC): Infrared imaging with the CHARA Array - Monnier et al. 2004, SPIE, 5491, 1370 (pdf)
Michigan Infrared Combiner (MIRC): Commissioning Results at the CHARA Array - Monnier et al. 2006, SPIE, 6268, 1 (pdf)
High precision interferometer: MIRC with photometric channels - Che et al. 2010, SPIE, 7734, 2
Imaging from the first 6-beam infrared combiner - Che et al. 2012, SPIE, 8445, 0
The MIRC-X 6-telescope imager: Key science drivers, instrument design and operation - Kraus et al. 2018, SPIE, 10701, 23
MIRC-X/CHARA: sensitivity improvements with an ultra-low noise SAPHIRA detector - Anugu et al. 2018, SPIE, 10701, 24