Lunar occultations in the infrared: Evolution from single element detectors to sub-arrays

T. Chandrasekhar*
Physical Research Laboratory, Ahmedabad 380 009, India

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Lunar Occultations is an elegant high angular resolution technique capable of reaching one dimensional resolutions of a few milliarc seconds on a large number of sources in the celestial path of the moon. At PRL we have been pursuing this method for nearly two decades at the 1.2m telescope of Mt Abu Observatory mainly in the near IR K band with a few excursions into the L band. Many of the resolved sources are late type M Giants, AGB variables (SRVs and Miras) and carbon stars. Apart from effective temperatures, the presence, extent and sometimes the structure of the circumstellar material could be inferred from high S/N occultation light curves. The IR instrumentation for observing lunar occultations has progressed from single element InSb based fast photometers to using area of interest sub-arrays of the NICMOS camera at Mt Abu. Details of sub-array mode and some recent science highlights are presented.

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Keywords : lunar occultation – infrared – subarray – dust shells