New Adaptive Optics Module for Interferometry
NAOMI, or the New Adaptive Optics Module for Interferometry, has put the Very Large Telescope Interferometer (VLTI) on steroids. NAOMI modules have been installed on each of ESO’s 1.8-metre Auxiliary Telescopes (ATs), which form part of the VLTI at Paranal Observatory, bringing adaptive optics technology to the ATs.
Why? The ATs were originally equipped with a visible-light sensor called STRAP or System for Tip/tilt Removal with Avalanche Photodiodes. The STRAP system used a fast-steering mirror to correct the slight, but rapid, motion of the image of a star caused by the turbulence of the Earth's atmosphere. Under good seeing conditions, STRAP provided corrections that allowed astronomers to observe with the VLTI. But the system had limitations — as soon as the conditions in the atmosphere degraded below a seeing of 1 arcsecond, the quality of the observations instantly decayed. With NAOMI, the observations are able to continue even when the conditions are less than superb, and they are better under all conditions.
The goal of the project was to equip all four ATs with NAOMI modules, which contain a basic adaptive optics (AO) system, in place of the current STRAP sensor. As the ATs are small telescopes, they don’t require as large an AO system as SPHERE; NAOMI’s smaller modules are sufficient to get the job done. With NAOMI, the ATs are less sensitive to atmospheric conditions. The sensitivity of the VLTI’s current instruments like PIONIER has been improved and second-generation instruments like GRAVITY and MATISSE are able to reach their full potential.
The four NAOMI modules arrived on Paranal in the first half of 2018.
This table lists the global capabilities of the system. The authoritative technical specifications as offered for astronomical observations are available from the Science Operation page.