We have made a submillimeter-wave telescope for a Japanese sounding rocket, S- 520-17, which is dedicated for an observation of cold dust in Orion molecular cloud region. The system is now under test for launch in Jan. 1995. The telescope include an off-axis Gregorian telescope with aperture of 30 cm, focal plane bolometer array, cryogenic cooling system down to 0.3 K, and a star sensor using charge modulation device. A very low emissivity optical arrangement of less than 1% is achieved using pure aluminum mirror, off axis reflector and cold optics. Single moded conical feed horn is effectively coupled with bolometers with efficiency of more than 90%. The focal plane array consists of 12-element bolometers, six for 250 micrometers observation and six for 500 micrometers observation. NEPs of the bolometers are 5 X 10-17W/√Hz which is read out by AC bridge read-out circuit. Total system gives sensitivities of about 10-12W/cm2 X sr for diffuse objects or 2 Jy for compact objects at 500 micrometers over 100 deg2 region with a beam sizes of 10 arcmin. This observation gives unique data on cold dust distribution, which is believed to dominate the dust mass distribution, over Orion Molecular Cloud region.
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