In the frequency range from 1 to 2 GHz discrepancies exist between the values of-the solar flux density observed at several stations. In order to clarify the situation a new absolute calibration has been carried out by the HHI at 1470 MHz. The equipment used for this purpose consists of an electromagnetic horn with calculated gain and of a receiver, the temperature scale of which has been calibrated by comparison with the noise of a heated absorber. The noise temperatures of the absorber have been identified with the mean thermodynamic temperatures of the absorbing material. The calibration procedure of the receiver and the observation method of the sun's radiation are described. An error analysis is given in detail, including impedance mismatches of the microwave components as well as impedance variations of the heated absorber. A maximum uncertainty of about • 1.7 % is calculated.

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The solar eclipsc 1966 May 20 was observed at 3.2, 10, 15, 20, 54, 59 cni, 1.05, 1.34 and 2.7 m wavelength b j the observatories of tlie Heinrich-Hertz-Institut. The meter-wavelength observations were superposed b y a noise stormThe result shows a region of enhanced radiation from the plages near the central meridian at the short wavelengths Consulting additionally the observations made at Kiel, N E K h , and OndYejov in thc rcgion of about 1.2 in wavelengtl i t is possible t o localize the source of the noise storm.The annular eclipse 1966 May 30 was observable by the stations of the Heinrich-Hertz-Institut at Berlin-Adlershof, Neustrelitz, and Potsdarn-Tremsdorf, but only as a partial eclipse. Table I shows the optical data of the eclipse at the three stations. The technical parameters of the instruments used for these observations are given in table 2 . T a b l c I . O p t i c a l d a t a of t h e e c l i p s e Results of the measurementsDuring the eclipse period, the sky was cloudy. A t Adlershof, slight rain fell a t the beginning of the eclipse, a t Neustrelitz it was raining near the end of the eclipse, thus influencing slightly the measurements at 3.2 cm wavelength.In figure Ia-c, the occultation curves recorded at the different wavelengths, are shown. The corresponding geometrical occultation curves are given for the three stations too.At 2.7 m wavelength the record is superposed by a noise storm. Therefore the occultation curve is not reproduced here. At 1.05 m and 1-34 m wavelength, however, the influence of this storm was much weaker, so that the occultation curves could be derived from the lower envelope of the records.The undulation at 19.9 cm wavelength in the first part of the occultation curve is due t o ground interference. This effect could not be eliminated, because the records on the days before and after the eclipse as well as on the corresponding day one year before do not show the same interferences,

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