The MMT Observatory: Entering a new era of scientific discovery

The MMT Observatory, a joint venture of the Smithsonian Institution and the University of Arizona, will soon celebrate the 40th anniversary of the dedication of its innovative Multiple Mirror Telescope. The original 4.5-m telescope, consisting of six 1.8-m mirrors on a common mount, operated productively for nearly 20 years until it was decommissioned to install a new telescope. The new MMT, which was dedicated in 2000, is equipped with a monolithic 6.5-m borosilicate primary mirror. The new telescope will soon surpass the operating lifetime of the original telescope. Coincident with this transition, the MMT will enter a new era of scientific discovery with the addition of new instrumentation and improved capabilities. This paper provides an overview of the current telescope and instrument configurations and then highlights recent and forthcoming developments, including new and upgraded instrumentation, that will usher in this new era. For example, a new high throughput wide-field multi-object imaging spectrograph with a long-slit mode, Binospec, was recently commissioned at the MMT. This powerful new instrument will very likely become a highly productive workhorse instrument in dark and grey time. Another major advancement that is underway at the MMT is a full redesign and refurbishment of the world's first adaptive secondary mirror. This effort, dubbed the MMT Adaptive Optics exoPlanet characterization System (MAPS), will result in a cutting edge AO system with a performance that greatly exceeds the original, now 20-year old, system. This system, together with the NIR spectrograph ARIES and the imaging- and spectropolarimeter MMTPol, provides some unique and powerful capabilities.