Measurements of the decimeter radiation from Jupiter

Jupiter was observed at a frequency of 1440 Mc/sec on 33 nights during August and September of 1961 using the Naval Research Laboratory 84-ft radio telescope. Measurements were made on 16 nights in August with the feed horn oriented favorably with respect to the polarized component of radiation, and on 17 nights in September with the horn in the orthogonal or unfavorable position. The average equivalent blackbody temperatures recorded were +300 rms and +400 rms, respectively. The data can be reasonably interpreted to indicate a degree of linear polarization of 25 to 45%, which is compatible with the 33% polarization reported by Radhakrishnan and Roberts at 960 Mc/sec and 28% reported by Morris and Berge at 1390 Mc/sec. Variations in disk temperature were observed which are consistent with the previous observations made at 1430 Mc/sec by McClain, Nichols, and Waak, who suggested a correla- tion with rotation of the planet. Strong independent evidence for a correlation with rotation is given by the measurements of Morris and Berge that argue for a model in which Jupiter's magnetic poles are in- clined 9 +3 to the planet's rotational axis, and located at 20 + 10 and 200 + 10 System III longitude ( ) Least-squares analyses of our data show a consistency with the above model, and indicate that the magnetic pole near 20 longitude is located in the northern hemisphere.