Arnica: the Arcetri Observatory Nicmos 3 Imaging Camera

ARNICA (ARcetri Near Infrared CAmera) is the imaging camera for the near infrared bands between 1.0 and 2.5 m that Arcetri Observatory has designed and built as a general facility for the TIRGO telescope (1.5 m diameter, f/20) located at Gornergrat (Switzerland). The scale is 100 per pixel, with sky coverage of more than 40 40 on the NICMOS 3 (256 256 pixels, 40 m side) detector array. The optical path is compact enough to be enclosed in a 25.4 cm diameter dewar; the working temperature is 76 K. The camera is remotely controlled by a 486 PC, connected to the array control electronics via a ber{optics link. A C{language package, running under MS{DOS on the 486 PC, acquires and stores the frames, and controls the timing of the array. We give an estimate of performance, in terms of sensitivity with an assigned observing time, along with some details on the main parameters of the NICMOS 3 detector.