MMTF: THE MARYLAND-MAGELLAN TUNABLE FILTER

This paper describes the Maryland-Magellan Tunable Filter (MMTF) on the Magellan-Baade 6.5 m telescope. MMTF is based on a 150 mm clear aperture Fabry-Perot (FP) etalon that operates in low orders and provides transmission bandpass and central wavelength adjustable from similar to 5 angstrom to similar to 15 angstrom and from similar to 5000 angstrom to over similar to 9200 angstrom, respectively. It is installed in the Inamori Magellan Areal Camera and Spectrograph and delivers an image quality of similar to 0.'' 5 over a field of view of 27' in diameter (monochromatic over similar to 10'). This versatile and easy-to-operate instrument has been used over the past three years for a wide variety of projects. This paper first reviews the basic principles of FP tunable filters, and then provides a detailed description of the hardware and software associated with MMTF and the techniques developed to observe with this instrument and reduce the data. The main lessons learned in the course of the commissioning and implementation of MMTF are highlighted next, before concluding with a brief outlook on the future of MMTF and of similar facilities which are soon coming on line.