In astronomy, images with high angular resolution is very important because it will provide better information. Radio astronomy work at wavelengths more
than 1 mm. Therefore, to obtain a high resolution image, antenna with a very large diameter or by using a radio interferometer. Radio interferometer is a system that utilizes the concept of interference on radio waves observation. Bosccha Observatory have plans to use five antennas for radio interferometer (Hidayat et al. 2012). Observations in this final project using two telescopes/antenna, ATB2 and ATB3. Antenna diameter of ATB2 and ATB3 is 3 meter and has a distance 30 meter from each other. Characterization is performed at the beginning of the observations to determine the profile of ATB2 and ATB3 using 4 value of gain and 4 value of scan rate as a variable. Characterization and observations were made at a frequency of 1420 MHz (wavelength 21 cm). Observations were made during 4 months period. At the end of the observation fringe pattern was obtained. That means interference successfully detected on interferometer ATB2-ATB3. Observations of interferometer also using hydrogen telescope. The results are shown in this final project, as well as future development plans.