NOAO >   Observing Info >   Approved Programs >   2001A-0016

Small NOAO Logo

Proposal Information for 2001A-0016


PI: Celine d'Orgeville, Gemini Observatory, cdorgeville@gemini.edu
Address: University Park, 670 N. A'Ohoku Place, Hilo, Hawaii 96720

CoI: Chris Dainty, Imperial College
CoI: Nick Wooder, Imperial College
CoI: John Quartel, Imperial College
CoI: Brooke Gregory, CTIO
CoI: Maxime Boccas, CTIO
CoI: Mark Chun, Gemini Observatory

Title: Mesospheric sodium layer monitoring for laser guide star adaptive optics systems in Chile

Abstract: We propose to monitor the mesospheric sodium layer abundance and altitude above Cerro Tololo for the purpose of characterizing sodium laser guide stars (LGS) for adaptive optics (AO) systems on the Gemini South and SOAR telescopes. Observations with facility adaptive optics is limited to certain areas on the sky due to the requirement of a stellar source to measure the wavefront distortions. A solution to this sky coverage problem is to use resonant backscattering of a laser beam by mesospheric sodium atoms as an artificial wavefront reference. In this technique, knowledge of the sodium abundance is crucial to determine the laser power required to produce guide stars of sufficient brightness and to efficiently correct for atmospheric distortions with adaptive optics. We request long-term status in semesters 2001A, 2001B and 2002A to determine the yearly and nightly variations of the mesospheric sodium layer versus time and altitude, as well as the rate of appearance and intensity of sporadic layers. The LGS AO facilities laser power requirement will be derived from the periodic minimum average sodium column density over the year. Knowledge of the mesospheric sodium behavior will enable refinements of simulated LGS AO performances. Finally, prediction of times of highest and lowest sodium densities will also give insight on the most efficient periods to plan LGS AO observations.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2001A-0016

noaoprop-help@noao.edu

Small NOAO Logo