ISLE: a general purpose near-infrared imager and medium-resolution spectrograph for the 1.88-m telescope at Okayama Astrophysical Observatory

摘要

ISLE is a near-infrared (1.0-2.5 μm) imager and spectrograph for the Cassegrain focus (f/18) of the 1.88 m telescope at Okayama Astrophysical Observatory. The detector is a HAWAII 1024 x 1024 HgCdTe Array, which covers 4.2 x 4.2 arcmin~2 field of view with a pixel scale of 0.25 arcsec/pixel. ISLE also provides medium (R=300 - 4800) resolution long-slit (4 arcmin long) spectroscopic capabilities using reflection gratings. A dedicated front-end electronics for the detector achieved a readout noise of 8 electrons by the conventional Fowler sampling, and a operation scheme that combined with a number of discarded readout greatly suppressed the reset anomaly. The measured limiting magnitudes were J=18.6 and K = 17.7 (imaging of point sources at S/N=10 for 10 min. exposure).