MIRIS is the main payload of the STSAT-3 (Science and Technology Satellite 3) and the first infrared space telescope for astronomical observation in Korea. MIRIS space observation camera (SOC) covers the observation wavelength from 0.9μm to 2.0μm with a wide field of view 3.67∘×3.67∘ . The PICNIC HgCdTe detector in a cold box is cooled down below 100K by a micro Stirling cooler of which cooling capacity is 220mW at 77K. MIRIS SOC adopts passive cooling technique to chill the telescope below 200 K by pointing to the deep space (3K). The cooling mechanism employs a radiator, a Winston cone baffle, a thermal shield, MLI (Multi Layer Insulation) of 30 layers, and GFRP (Glass Fiber Reinforced Plastic) pipe support in the system. Optomechanical analysis was made in order to estimate and compensate possible stresses from the thermal contraction of mounting parts at cryogenic temperatures. Finite Element Analysis (FEA) of mechanical structure was also conducted to ensure safety and stability in launching environments and in orbit. MIRIS SOC will mainly perform Galactic plane survey with narrow band filters (Pa α and Pa α continuum) and CIB (Cosmic Infrared Background) observation with wide band filters (I and H) driven by a cryogenic stepping motor.

We have preliminarily designed two infrared optical systems of the multi-purpose infrared camera system (MIRIS) which is the main payload of STSAT-3. Each optical system consists of a Cassegrain telescope, a field lens and a 1:1 re-imaging lens system that is essential for providing a cold stop. The Cassegrain telescope is identical for both of two infrared cameras, but the field correction lens and re-imaging lens system are different from each other because of different bands of wavelength. The effective aperture size is 100mm in diameter and the focal ratio is f/5. The total length of the optical system is 300mm and the position of the cold stop is 25mm from the detector focal plane. The RMS spot size is smaller than 40μm over the whole detector plane.

KASI (Korea Astronomy and Space Science Institute) is developing the near-infrared camera system named KASINICS (KASI Near-Infrared Camera System) which will be installed at the 60cm f/13.5 Ritchey-Chretien telescope of the Sobaeksan Optical Astronomy Observatory (SOAO). The camera system is optimized for JHKL bands and has a 6 arcmin FOV. The optical system consists of two spherical mirrors and a 8-position filter wheel. With the exception for the dewar window, all optical elements are cooled inside cryogenic dewar. Since the Offner system is adopted to prevent thermal noises from outside of the telescope primary mirror, the secondary mirror of the Offner system acts as a cold Lyot stop. The optical performance does not change by temperature variations because the Aluminum mirrors contract and expand homogeneously with its mount. We finished the design and fabrication of the optical parts and are now aligning the optical system. We plan to have a test observation on 2006 January.

Open clusters are useful tools to investigate the structure and evolution of the Galactic disk. We have started a long-term project to obtain UBVI CCD photometry of open clusters which were little studied before, using the Doyak 1.8 m telescope of Bohyunsan Optical Astronomy Observatory in Korea. The primary goals of this project are (1) to make a catalog of UBVI photometry of open clusters, (2) to make an atlas of open clusters, and (3) to survey and monitor variable stars in open clusters. Here we describe this project and report the first results based on preliminary analysis of the data on four open clusters in the survey sample: Be 14, Cr 74, Biu 9, and NGC 2355. Isochrone fitting of the color-magnitude diagrams of the clusters shows that all of them are intermediate age to old (0.3-1.6 Gyrs) open clusters with moderate metallicity.