WIYN High Resolution Infrared Camera (WHIRC)
The WIYN High Resolution Infrared Camera (WHIRC) is a high resolution near infrared imager (0.8-2.5 mm) designed to produce superb images over a moderate (3.3′ x 3.4′) field of view on the WIYN 3.5 m telescope at Kitt Peak National Observatory. It takes scientific advantage of the excellent image quality produced by the telescope and its image stabilization subsystem, the WIYN Tip Tilt Module (WTTM), which is located on one of two Nasmyth ports. WHIRC mounts to WTTM, and reimages the WTTM focal plane to a plate scale of 0.1″ per pixel at the WHIRC detector. Its straight through optical path makes for a compact, very low mass instrument; a necessity given the stringent moment loading requirement at the WTTM interface. The WHIRC optical path consists of a vacuum window, a five-element collimator, a dual filter wheel, a five-element achromatic camera, and finally a 2k2Raytheon VIRGO mercury cadmium telluride (HgCdTe) detector. A novel all-aluminum lens cell design is used to achieve 13 um lens centering tolerances between critical elements at the 77K operating temperature. A suite of thirteen filters facilitates broad-band (J, H, Ks) imaging as well as narrow-band imaging tailored to a variety of astronomical investigations. The imaging performance of WHIRC is excellent. Irrespective of seeing, the telescope, and WTTM, WHIRC delivers 0.13″, 0.11″, and 0.08″ FWHM images in J, H, and Ks, respectively. On sky, the imaging is equally impressive yielding images as good as ~ 0.25 FWHM in Ks.