Expertise in Astronomical Instrumentation

CHARA/MIRC-X (AJ 2020, SPIE 2018)

The MIRC-X instrument combines the light from six telescope beams of the CHARA array (left) and forms a virtual telescope up to 660 meters across and delivers 0.5 milliarcsecond angular resolutions using a technique called interferometry. MIRC-X is the world's best imaging machine in near-infrared.

MIRC-X beam combiner uses a state-of-the-art eAPD based CRED-ONE camera from "FirstLight Imaging" and delivers very high sensitive observations than previously achieved for imaging at CHARA. These sensitive MIRC-X observations combined with 0.5 milliarcsecond angular resolutions aim to observing fainter stars such as protoplanetary disks and binaries. MIRC-X was installed in 2019.

The performance of MIRC-X instrument at avalanche Gain=1, 10 and 40. It delivers 2-magnitude of higher sensitivity in H-band using avalanche Gain = 40.

VLTI GRAVITY (My papers 1, 2 and 3)

The GRAVITY combines the light of four telescopes of the Very Large Telescope Interferometer, Paranal, Chile and delivers 3 milliarcsecond angular resolution and 50 microarcsecond astrometry. GRAVITY has several first technology implementations, state-of-the-art SAPHIRA detectors, integrated optics and beam stabilization methods.

GRAVITY has revolutionized the field of optical interferometry with higher sensitivity (K<15) and precise astrometric (<50microarcseconds) measurements. GRAVITY has delivered breakthrough results in the field of Galactic Center black hole and exoplanet characterization.

CHARA adaptive optics (SPIE 2020)

The CHARA Array is the longest baseline optical interferometer in the world. To achieve ambitious observations of faint targets such as young stellar objects and active galactic nuclei, higher sensitivity is required. For that purpose, adaptive optics are developed to correct atmospheric turbulence and non-common path aberrations between each telescope and the beam combiner lab. Our six telescopes and 12 AO systems with tens of critical alignments and control loops pose challenges in operation.

Anugu contributed software for this project especially played a huge role in low-latency data acquisition from the WFS sensors.

Betelgeuse scope concept (SPIE 2020)

We propose to exploit the common mount of the ARO12m radio antenna (a) and install 4-inch telescope array (b) to remove the large delay lines and each individual telescope tracking and pointing requirements to save money. Optical layout of the light collection unit of an individual telescope (c).

Conceptual sketch of the beam combiner. For simplicity, only six beams are shown here. The fibers transport the telescope beams to the beam combiner. The fibers are arranged non-redundantly on V-groove to allow various spatial frequency fringes. The beams are combined at the focus of the lens in the "all-in-one" beam combining scheme, and fringes are made. A cylindrical lens compresses the fringe pattern in the spectral direction, and then a prism disperses the light in the perpendicular direction to the spatial direction of fringes. Photometric channels are made with a beam splitter (20 flux split).

(Left) Squared visibility and closure phase from LBT Non-Redundant aperture Masking (NRM) and CHARA array observations made during the Great Dimming. The LBT and CHARA array baselines are not optimized for Betelgeuse -- LBT baselines being too short, and on the other hand, the CHARA array baselines are too long. (Right) Expected observables of 12m baseline Betelgeuse scope. The Betelgeuse scope covers both the LBT and CHARA array spatial scales and fills the gap.

A simulated Betelgeuse image at 700 nm (Chiavassa et al. 2010). (B and C) Expected images of Betelgeuse surface for B=12m and 6.1m baselines based Betelgeuse scope. The R-band 6.1m angular resolutions 11mas are equivalent to IOTA/IONIC (Haubois et al. 2009). The Betelgeuse scope with 12m baselines images can be highest in angular resolution until the E-ELTs or even better considering E-ELT poor Strehl ratios in the visible wavelengths.