Kiso observatory near-infrared camera with a large format array

We have constructed a near-infrared camera with a 1040 by 1040 PtSi CSD array for astronomical use. The camera is attached to the prime focus (f/3.1) of the 105 cm Schmidt telescope at Kiso observatory. The field of view is 18.4 by 18.4 arcmin ² and the spatial resolution is 1.06 by 1.06 arcsec ²/pixel. The camera can be used mainly in J (λ _eff = 1.25 micrometer), H (1.65 micrometer), and K′ (2.15 micrometer) bands. Since thermal emissions from the atmosphere and room-temperature bodies are main background noise sources in the near-infrared, we designed a cold baffle inside the camera to minimize the effect of the thermal radiation from the telescope. Both the charge transfer efficiency and the dark current of PtSi arrays are sensitive to the array temperature. Therefore we carefully control the temperature at 60 ± 0.05 K by using a refrigerator and a temperature controller. The readout noise was reduced to 70 ē by adopting a correlated multiple sampling technique. The array response was linear within 0.7% accuracy below 25% of the full well capacity (< 4.0 × 10 ⁵ ē).