POETS: Portable Occultation, Eclipse, and Transit System

Abstract

Occultations of stars by small bodies in the outer solar system are opportunities to make high-resolution measurements of their geometries and orbital elements and to detect or probe their atmospheres. Such events are limited in space and time, so it is desirable to deploy highly capable camera systems on multiple fixed and/or portable telescopes anywhere in the world, potentially on short notice. Similar considerations apply to planetary transits and solar eclipses. We have designed a camera system called POETS (Portable Occultation, Eclipse, and Transit System), which is optimized for occultation and related observations, and have assembled five such systems. The core of this system is the Andor Technology DV-887 (now DU-897) frame-transfer camera, featuring a high frame rate, minimal dead time, high quantum efficiency, and low read noise. An electron-multiplying mode lowers effective read noise to below 1 e- pixel-1 and is capable of photon counting. Each POETS includes a compact GPS timing system with microsecond accuracy, and a high-performance computer system capable of sustained fast frame rates. Each POETS is designed to be transportable as carry-on luggage and is adaptable to a wide variety of sites. POETS were deployed for the first time for the 2005 July 11 Charon occultation event, and they performed extremely well on telescopes with apertures from 0.6 to 6.5 m. Three POETS were subsequently deployed for the 2006 March 29 total solar eclipse, and five for the 2006 June 12 Pluto occultation.