Decarnetric radiation from Jupiter. I. Synoptic observations 1957-1961

Abstract

A review of the observational problem introduces the equipment and techniques used at the Yale Ob- servatory through 1961 for monitoring Jovian decametric radiation. Assignment of rigid objective criteria to the definition of observing time and to Jupiter storm identification makes possible the tabulation not only of identified storms but also of times when Jupiter was positively not radiating toward the earth with a flux greater than 10-21 W cps-' on the frequencies being monitored. From these data are derived occurrence frequency and occurrence probability statistics as functions of System III (1957.0) longitude and of frequency and year of observation. The tri4obed character of the oc- currence probability histogram and the total absence of events from one quadrant are conspicuous, with cor- responding implications for freedom from non-Jovian events. The 1959 minimum in occurrence probability appears to be real; coincidence with maximum geomagnetic activity is remarked. Structural characteristics of individual storms are briefly discussed, including amplitude fluctuations and the tendency for relatively sharp onset and decay of particularly strong activity. Peak radiated decametric powers between 1000 and 1001 W are indicated, depending strongly on the spectrum at the low-frequency end, although the average power is closer to 10 -10 W. Improved upper limits on decametric emission from other planets and on the optical emission from Jupiter are noted.