Study on the precise observations of stellar and circum-stellar phenomena with the optical and infrared interferometer

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This research project (MIRA-I.2) is aimed to develop the optical and infrared interferometer for observing stars with the very high angular resolution. The term of this project is 4 years (Apr. 1998 - Mar. 2002).In 1998, interferometer optics, detectors, and control system were investigated, partly made and tested. These parts were built into the former interferometer system, MIRA-I.1, which consists of two coude telescopes (250 mm aperture, 4 m baseline). Fringes of several bright stars were detected with this system. In 1999, the coude telescopes were replaced with the new element telescopes of siderostat (300 mm flat mirror, the test system of 6 m baseline). The construction of the new observing houses for the regular system of MIRA-I.2 (30 m baseline) was begun along with the setup of the test baseline system of 6 m. In 2000, we made the construction and the setup of new observing houses, vacuum pipes for optical path, optical parts in the observing house, interferometer optics, fringe detectors, quadrant sensors for tip-tilt mirrors, and vacuum chamber for delay line in the interferometer laboratory. In 2001, the interferometer system of 6 m test baseline was completed. At the end of June, 2001, fringes of several bright stars were detected with this system. In August, after this success, we started the construction of the regujar system of 30 m baseline in full-scale. Test observations of bright stars were begun in October, 2001. However, we could not detect the star fringes until March, 2002 (the end of 2001 fiscal year).Making improvements and regulations of the system, we succeeded to detect the fringes of Vega with the regular MIRA-I.2 system of 30 m baseline, in June, 2002. We will complete this interferometer, which is worth observing the physical parameters, such as radius and mass of stars.