Though Jupiter had been quiet for several months except for SEB activity, interesting phenomenon was observed late February.

Preceding RS, SEB had generally been dark and more stable than that following RS, where it is usually disturbed. Late February, however, suddenly appeared light area had partly fade SEBn preceding RS. Yunoki's image taken on Feb. 27 showed white bar about 15 deg. long in SEBn at II:30 deg., where SEB northern component almost disappeared. And strongly bluish SEBn just preceding it showed striking contrast in this region. This activity may affect EZ, where EZs was slightly disturbed with bluish dark features. It can clearly be seen in some images taken on Feb. 25 by Akutsu, Einaga, Fukui, Mishina, and Yunoki, and even in methane band image by Akutsu, this region was lighter than surroundings. But there was no such feature in Feb. 20, though bubble-like white spots were seen in slightly disturbed bluish SEBn. Therefore, it is seemed that this activity began between Feb. 20 and 25, and rapidly developed.

Typical phenomenon in this latitude is rifting of SEBn induced by EZs white oval - that is, white cloud in SEBZ is drawn into EZs white oval breaking SEBn, when it passes north of RS, and it sometimes become conspicuous preceding RS. This phenomenon was frequently observed between late 1970s and early 1980s, when long-lived EZs white oval persisted. In this activity, no white oval was seen in EZs, and the region appeared to be no relation with SEBZ light band stretching from RS. Because there seems to be no recent instances of such partial fading of SEBn, we should keep careful watch for this region.

Mid-SEB outbreak was still active, continuing to emerge new white spots from about II:140 deg., though the region was generally quieter with few prominent spots. Therefore, it was difficult to distinguish mid-SEB outbreak activity from original disturbed region which had ordinary been seen following RS. Potentially, original disturbed region might have disappeared in early stage of outbreak, and current mid-SEB outbreak would transform into ordinary disturbed region.

RS was prominently orangish with darker core at its center, leaving dark arch along its southern edge and dusky spots at both ends, though they became very weak. STB dark spot had overtaken RS, but no change was observed. RS was almost stationary at II:91.4 deg. (Feb. 18, Ota).

BA was at II:162.0 deg. (Feb. 16, Yunoki), clearly seen as white oval surrounded by dark collar. STB had completely revived between BA and about II:260 deg., where it was dark and broad belt trailing dark spots chain spanning about 40 deg. long in slightly higher latitude. Between RS and BA, north component of STB was clearly seen, too.

In northern hemisphere, NEB showed violent rift activity, where belt interior disturbed with irregular light streak and spots. Its range was from II:310 deg. to 70 deg. late February. But it is identical with the rift seen early January between II:180 deg. and 260 deg., since it has been prograding at about -4 deg./day much faster than System II.

(2) Saturn

In February, Saturn crossed the meridian 21-20 o'clock, and time range for observation shifted to hours before midnight. This month, we have received observations listed below.

In this apparition, white and dark spots had observed nearly every month on Saturn, but it was quiet without notable changes this month, except for a dark spot at temperate latitude taken by Colville on Feb. 18.

Orangish temperate latitude and blue-green tint of higher latitude showed beautiful contrast against light and whitish EZ.

(March 9, K. Horikawa)

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