Performance of the WIYN high-resolution infrared camera

Abstract

We present the design overview and on-telescope performance of the WIYN High Resolution Infrared Camera (WHIRC). As a dedicated near-infrared (0.8-2.5 &mu;m) camera on the WIYN Tip-Tilt Module (WTTM), WHIRC will provide near diffraction-limited imaging with a typical FWHM of ~0.25". WHIRC uses a 2048 x 2048 HgCdTe array from Raytheon's VIRGO line, which is a spinoff from the VISTA project. The WHIRC filter complement includes <i>J, H K_S</i>, and 10 narrowband filters. WHIRC's compact design makes it the smallest near-IR camera with this capability. We determine a gain of 3.8 electrons ADU^-1 via a photon transfer analysis and a readout noise of ~27 electrons. A measured dark current of 0.23 electrons s^-1 indicates that the cryostat is extremely light tight. A plate scale of 0.098" pixel^-1 results in a field of view (FOV) of ~3' x 3', which is a compromise between the highest angular resolution achievable and the largest FOV correctable by WTTM. Measured throughput values (~0.33 in <i>H</i>-band) are consistent with those predicted for WHIRC based on an elemental analysis. WHIRC was delivered to WIYN in July 2007 and was opened for shared risk use in Spring 2008. WHIRC will be a facility instrument at the WIYN telescope enabling high definition near-infrared imaging studies of a wide range of astronomical phenomena including star formation regions, proto-planetary disks, stellar populations and interstellar medium in nearby galaxies, and supernova and gamma-ray burst searches.