ISLE: Near-Infrared Imager/Spectrograph for the 1.88m Telescope at Okayama Astrophysical Observatory

摘要

ISLE is a near-infrared imager and spectrograph for the Cassegrain focus (f/18) of the 1.88 m telescope at Okayama Astrophysical Observatory. It is upgraded instrument with a new detector, HAWAII-1 HgCdTe array and new optics. ISLE provides imaging capabilities which covers 4.2 × 4.2 arcrnin~2 field-of-view at 0.25 arc-sec/pixel and long-slit (4 arcinin) spectroscopic capabilities at λ/Δλ = 1000 - 4000 using reflection gratings. The noise performance of the detector is excellent. The read noise of 2.5 electrons with 25 Fowler pairs has been achieved, that is one of the world's lowest level among the instruments which use HAWAII-1 array as the detector. We discuss the technical performance of ISLE and examine the upgrade effectiveness.