Adaptive Optics System
A Brief Description:
Adaptive Optics (Unavailable): The f/15 adaptive secondary was built by the University of Arizona and Arcetri Observatory in Italy. The thin glass shell is 2mm thick and 640 mm wide and is deformed by over 300 voice coils. It is used with instruments such as ARIES, PISCES, MIRAC and Clio. For instructions on how to propose to use the adaptive optics system please see here. NEW: the AO system will be undergoing upgrades and will be temporarily unavailable after 2017A.
The Fundamental Capabilities:For natural guide star observing, wavefronts may be corrected at full speed for objects of V ~ 11-12 magnitude, depending on conditions. For target stars as faint as V ~ 13.5-14, fewer corrections can be applied, but improvements in image quality over the natural seeing are possible. If the target star is fainter than V~14 you may choose one of the following options. 1. Leave the mirror flat and do no corrections. 2. Use a very nearby (less than 20-30 arcseconds away) brighter star to correct on. 3. Close the loop on a nearby bright star and “fix” the shape of the mirror, then return to the target star. Keep the mirror stationary for the duration of the science observations. Further Information: When the f/15 is mounted the wind constraints are tighter to protect the deformable secondary mirror. If pointing into the wind and the wind is sustained at 25 mph or gusting above 30 mph, then we must close. If pointing away from the wind and the wind is sustained at 30 mph or gusting above 35 mph, the front shutters must be closed. Additionally, if the wind is coming out of the North-East or East, then it arrives at the telescope over Mt Wrightson and the ridge. This causes major turbulence above the telescope and will degrade the seeing and make it highly variable. In this case, there is nothing we can do to improve the conditions other than wait for the wind to change direction. Overhead for setting up AO at the beginning of the night is estimated to be 30 minutes, with an additional 15 minutes for each new object during the night. Please include this in overhead estimates when planning your run. For additional information on the MMT NGS-AO system performance see: “MMT AO Performance: Analysis and Status.” For a presentation of early science results, click here. For more information, please contact adaptive optics scientist and engineer Keith Powell.