Magellan II's Adaptive Optics Top Hubble's Resolution

muon-catalyzed writes "The incredible 'first light' images captured by the new adaptive optics system called Magellan|AO for "Magellan Adaptive Optics" in the Magellan II 6.5-meter telescope are at least twice as sharp in the visible light spectrum as those from the NASA's Hubble Space Telescope. 'We can, for the first time, make long-exposure images that resolve objects just 0.02 arcseconds across — the equivalent of a dime viewed from more than a hundred miles away,' said Laird Close (University of Arizona), the project's principal scientist. The 6.5-meter Magellan telescopes in the high desert of Chile were widely considered to be the best natural imaging telescopes in the world and this new technology upgraded them to the whole new level. With its 21-foot diameter mirror, the Magellan telescope is much larger than Hubble with its 8-foot mirror. Until now, Hubble always produced the best visible light images, since even large ground-based telescope with complex adaptive optics imaging cameras could only make blurry images in visible light. The core of the new optics system, the so-called Adaptive Secondary Mirror (ASM) that can change its shape at 585 points on its surface 1,000 times each second, counteracts the blurring effects of the atmosphere."

Comments

Hubble resolution, at a price

[simonbp]

What they rarely mention in these sorts of press releases (everyone with AO system has a "better than Hubble" press release) is that the cost of getting to that resolution is losing most of the light along the way. It's not hard to beat HST with perfect atmospheric correction, as Hubble is only a 2.4 m aperture, and nearly every AO system is on a larger telescope. It's just that the correction is achieved by sufficient optical contortions that only a small fraction of the original light actually makes it to the detector.

My personal experience is that even the largest and most sensitive AO system in the world (NIRC II on Keck II with laser guide star) still really struggles make an observation in 20 minutes that Hubble can do in 5 minutes. If anyone were to launch a >3 m aperture visual-band space telescope (NOT JWST, that's IR), it would blow all these AO systems out of the water.