6.5.1 Early Radio Observations
In Japan, radio astronomy began with the observations of solar noise in the late
1940s at the following four institutes (Orchiston and Ishiguro 2017):
1. Osaka University. Oda Minoru (see Sect. 6.6) and Takakura Tatsuo observed
solar noise at 3300 MHz using a handmade horn in 1949–1951. Later they moved
to Osaka City University.
2. The Research Institute of Atmospherics (空電研究所), Nagoya University,
Toyokawa. Tanaka Haruo and Kakinuma Kiyotaka began solar radio observations in 1950 with a 2.5-m dish operating at 3700 MHz. In 1953, they constructed
a five-element interferometer consisting of a 1.5-m dish at 4000 MHz. The
interferometer was later expanded to eight elements and was used for observations of the brightness distribution of radio emissions on the solar surface, along
with observations of dynamic solar bursts.
3. Tokyo Astronomical Observatory. Hatanaka Takeo (Chap. 3) and Moriyama
Fumio constructed a 5 Â 5-m radio telescope at 200 MHz and began observations
of solar radio bursts in 1949. They successively constructed a 10-m parabolic dish
(200–3000 MHz) in 1953 and a 12-m parabolic dish (9500 MHz) in 1957. These
telescopes were used for solar radio observations, particularly for solar radio
bursts.
4. Hiraiso Station, Radio Research Institute of the Ministry of Posts and Telecommunications (郵政省電波研究所、平磯電波観測所). In 1950, a broadside
array was erected by Obayashi Tatsuzo operating at 61.2 MHz for solar noise.
It was replaced in 1952 by a new 200-MHz array for the regular monitoring of
solar noise, and this was operated during the 1950s.
The Sun often demonstrates violent burst phenomena that are usually classified
into Type I to Type V based on the structure of the frequency space that changes with
time. Each type is also associated with some active phenomena such as flares,
eruptive prominences, and proton emissions. In the 1960s, Morimoto Masaki, Kai
Keizo, Takakura Tatsuo, and their group at the TAO observed extensively every type
of radio burst and carried out theoretical analysis for the mechanisms of bursts.
Figure 6.20 illustrates an example of a dynamic spectral structure of the Type IV
solar burst observed on September 11, 1957 (Takakura and Kai 1961).
Radio observations for galactic objects started with the construction of a 24-m
spherical-dish telescope at the Mitaka campus of the TAO and a 30-m parabolic
telescope at the Kashima Branch of the Radio Wave Institute of the Telecommunication Ministry (郵政省電波研究所鹿島支所) in the early 1960s. These telescopes
have been used mainly for HII regions and supernova remnants at 1420 and
4170 MHz.
158
6 Postwar Development of Astrophysics, 1946–2000 (Part I: Instrumentation)
In Japan, radio astronomy began with the observations of solar noise in the late
1940s at the following four institutes (Orchiston and Ishiguro 2017):
1. Osaka University. Oda Minoru (see Sect. 6.6) and Takakura Tatsuo observed
solar noise at 3300 MHz using a handmade horn in 1949–1951. Later they moved
to Osaka City University.
2. The Research Institute of Atmospherics (空電研究所), Nagoya University,
Toyokawa. Tanaka Haruo and Kakinuma Kiyotaka began solar radio observations in 1950 with a 2.5-m dish operating at 3700 MHz. In 1953, they constructed
a five-element interferometer consisting of a 1.5-m dish at 4000 MHz. The
interferometer was later expanded to eight elements and was used for observations of the brightness distribution of radio emissions on the solar surface, along
with observations of dynamic solar bursts.
3. Tokyo Astronomical Observatory. Hatanaka Takeo (Chap. 3) and Moriyama
Fumio constructed a 5 Â 5-m radio telescope at 200 MHz and began observations
of solar radio bursts in 1949. They successively constructed a 10-m parabolic dish
(200–3000 MHz) in 1953 and a 12-m parabolic dish (9500 MHz) in 1957. These
telescopes were used for solar radio observations, particularly for solar radio
bursts.
4. Hiraiso Station, Radio Research Institute of the Ministry of Posts and Telecommunications (郵政省電波研究所、平磯電波観測所). In 1950, a broadside
array was erected by Obayashi Tatsuzo operating at 61.2 MHz for solar noise.
It was replaced in 1952 by a new 200-MHz array for the regular monitoring of
solar noise, and this was operated during the 1950s.
The Sun often demonstrates violent burst phenomena that are usually classified
into Type I to Type V based on the structure of the frequency space that changes with
time. Each type is also associated with some active phenomena such as flares,
eruptive prominences, and proton emissions. In the 1960s, Morimoto Masaki, Kai
Keizo, Takakura Tatsuo, and their group at the TAO observed extensively every type
of radio burst and carried out theoretical analysis for the mechanisms of bursts.
Figure 6.20 illustrates an example of a dynamic spectral structure of the Type IV
solar burst observed on September 11, 1957 (Takakura and Kai 1961).
Radio observations for galactic objects started with the construction of a 24-m
spherical-dish telescope at the Mitaka campus of the TAO and a 30-m parabolic
telescope at the Kashima Branch of the Radio Wave Institute of the Telecommunication Ministry (郵政省電波研究所鹿島支所) in the early 1960s. These telescopes
have been used mainly for HII regions and supernova remnants at 1420 and
4170 MHz.
158
6 Postwar Development of Astrophysics, 1946–2000 (Part I: Instrumentation)