National Astronomical Observatory of Japan

Aerial Photo Showing the History of the Nobeyama Solar Radio Observatory


Aerial Photo Showing the History of the Nobeyama Solar Radio Observatory

In fiscal year 2014, Nobeyama Solar Radio Observatory was removed from NAOJ’s organization. Borrowing Shinshu University Faculty of Agriculture’s Nobeyama highlands site, it constructed and improved radio instrument arrays dedicated to studying the Sun for over 40 years following the completion of the Solar Radio Interferometer in 1970. Operations continued every day without a break, offering the world continuous observational data. The Solar-Terrestrial Environment Laboratory, Nagoya University, with the support of an international consortium, will continue to operate the currently active Radioheliograph; and NAOJ will continue to operate the Radio Polarimeters.

The Progression of Nobeyama’s Solar Radio Observation Instruments

The first 160 MHz Solar Radio Interferometer observed radio waves originating from midlevel elevations in the corona extending around the Sun. It is composed of 11 antennas deployed east-to-west (longest baseline 2.3 kilometers) and 6 antennas deployed north-to-south. Four of the east-west antennas and 2 of the north-south antennas are pictured. (They have orange mounts and 6 m diameter silver mesh parabolic dishes.) The two 70-600 MHz Radiospectrographs, which use antennas of this same shape (6 m and 8 m diameters) to observe time dependent changes in the spectrum (radio intensity frequency distribution), stand in-between the east-west antennas. After those, in response to the scientific need to observe solar flares with higher spatial and time resolution, the correlator type 17 GHz Solar Radio Interferometer (14 antennas at the left edge of the picture, 1-dimensional east-west, 1.2 meter diameters) started operation in 1978, observing radio waves originating from the chromosphere and lower corona. There were many handmade pieces, but the performance was epoch-making. That experiment led to the construction of the radioheliograph (the T shaped array in the center of the picture, 84 antennas, 80 centimeter diameters) which started observations in 1992. In addition, you can see the 17 GHz, 35 GHz and 80 GHz Polarimeter antennas in the bottom part of the picture.

Text by: Susumu Kawashima (NAOJ Chile Observatory)
Translation by: Ramsey Lundock (NAOJ)