The 91-cm Cassegrain reflector, equipped initially with a photoelectric photometer and a prism spectrograph, and then an IR photometer (1968), photoelectric
spectral scanner (1967), and an image tube spectral scanner (1980), had also been in
use. With intensive use of the 188-cm reflector, many observational results had been
produced even from the 1960s.
With this telescope, An Atlas of Stellar Spectra, Taken with the PrismSpectrogram of the 91-cm Reflector was published by Yamashita Yasumasa, Nariai
Kyoji, and Norimoto Yuji in 1976. A sample page is illustrated in Fig. 6.3.
Advances in the detector came about with the invention of the charge-coupled
device (CCD) by W. Boyle and G. E. Smith of Bell Telephone Laboratories in 1969.
0
10
20
30
40
50
60
70
80
1960
1965
1970
1975
1980
1985
Number of proposals at OAO
Newton
Cas
Coude
Total
Fig. 6.2 Number of proposals per year at OAO for first 23 years (OAO)
Fig. 6.3 Spectral atlas for K0V to M2V stars. (Yamashita et al. 1976)
6.3 Optical and Infrared Observatories
141