These tables were designed to aid observers in knowing when predicted Io and non-Io related decametric radio storms would occur. A description of each of the columns in the ephemeris table is given below:
UT Universal Time.
LamIII Lambda III (1965.0). This is the Jovian longitude facing the Earth at this date and time. This is also known as the Sub-Earth longitude or the Central Meridian Longitude (CML). Lambda I and II are the longitudes for cloud features at the Jovian equator and at Jovian mid-latitudes respectively. Lambda III is measured with respect to the rotating magnetic field which is tied to the interior of Jupiter.
Io Io Phase. The Io phase is the angle of Io in its orbit with respect to superior geocentric conjunction. In other words when Io is directly behind Jupiter as seen from Earth the Io phase is 0 degrees and when Io crosses in front of Jupiter as seen from Earth it is 180 degrees.
SubIo The sub-Io longitude. The Jovian longitude at which Io is transiting at the given date and time.Storm Type of decametric emission event. It has been found that the orientation of Jupiter and the position of the Jovian satellite Io in its orbit strongly influence the likelihood of emission from Jupiter in the decametric wavelengths (approximately 10 to 100 meters). Certain combinations of Lambda III and Io phase give rise to certain types of Jovian radio 'storms' These are the Io-related storms. Some storms appear to occur independent of the location of Io. These storms are non-Io related. The Lambda III and Io phase for the different storm types are:
Io-Related Storms Lambda III Io Phase Characteristics Io-A 200-290 195-265 RH polarized, mostly L Bursts Io-B 90-200 75-105 RH polarized, mostly S Bursts Io-C 290-10 225-250 LH polarized, L and S bursts Non-Io-Related Storms A 200-290 B 90-200 C 290-10
L-Bursts Bursts of long duration (typically 10 seconds)
S-Bursts Bursts of short duration (typically about 10 msec depending on the bandwidth of receiver)
Fla Calif The hour angle of Jupiter as seen from the University of Florida Radio Observatory and from the Owens Valley Radio Observatory, California. The values in this column indicate the number of hours until (negative) or past (positive) transit for Jupiter at the three locations. A value of 0.0 means Jupiter is on the local meridian at the given time.
Prob18 These are occurrence probabilities compiled by the University of Florida Radio Observatory from 1985 through 1992 using an 18 MHz Yagi antenna. The occurrence probabilities are computed by dividing the number of times that a storm has been heard for a given LambdaIII and Io Phase by the number of times the given LambdaIII and Io Phase has been listened to.
Prob26 These are occurrence probabilities compiled by the University of Florida Radio Observatory from 1973 through 1981 using the 640 dipole array operating at 26.3 MHz. The occurrence probabilities are computed by dividing the number of times that a storm has been heard for a given LambdaIII and Io Phase by the number of times the given LambdaIII and Io Phase has been listened to. Note:The significantly higher occurrence probabilities at 26 MHz over 18 MHz are not due to Jupiter being more active at this frequency but rather due to the much higher sensitivity we have with the 26.3 MHz array over the single Yagi antenna.
Questions or comments regarding the predictions can be sent to F. Reyes at reyes@astro.ufl.edu.
Prof. Kazumas a Imai has developed an interactive Jupiter ephemeris for observation.
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