Observational Concerns and Techniques for High-Background Mid-Infrared (5 – 20 micron) Array Imaging

Abstract

Broadband observations at 5–20 micron with large ground-based telescopes are dominated by thermal background radiation from the telescope optics, instrument and sky. Astronomical sources typically contribute less than one percent of the total detected flux. In most cases the direct, unprocessed image of a bright source (before background subtraction) is indistinguishable from an image of blank sky (Fig. 1). This paper gives an overview of the fundamental concepts, conditions and limitations of high-background mid-infrared imaging. The techniques used to acquire and process the image data are summarized, illustrated with examples from our 58 x 62 pixel mid-infrared camera astronomy program.