Abstract
We report on the development of a wide-field near-infrared (0.9–2.5$\, \mu$m) camera built as a renewal of the existing classical Cassegrain 0.91 m telescope at Okayama Astrophysical Observatory. The optics system was replaced with fast hybrid optics (f/2.5) composed of forward Cassegrain optics and quasi-Schmidt optics, which results in an effective image circle of 52 mm diameter on the focal plane. The new camera, called the Okayama Astrophysical Observatory Wide-Field Camera (OAOWFC), has imaging capabilities in the $Y$, $J$, $H$, and $K_{\rm s}$ bands over a field of view of $0.^{\!\!\!\circ }47 \times 0.^{\!\!\!\circ }47$ with a HAWAII-1 HgCdTe PACE focal plane array. The primary purpose of OAOWFC is to search for variability in the Galactic plane in the $K_{\rm s}$ band and to promptly follow up transients. We have demonstrated a photometric repeatability of 2% in the densest field in the northern Galactic plane and successfully discovered previously unreported variable stars. The observations of OAOWFC are fully autonomous, and we started scientific operations in 2015 April.
Okayama Astrophysical Observatory Wide-Field Camera