Broadened NEB was generally triple, being run through by dark component in the middle of the belt. It seems that this component may be former north component before broadening, and such aspect has been seen previous events like in 1988 and 2001. Inside NEB, white spots and light bands probably due to rift activity could be seen in some places, confined to area between s. edge and central component described above. Exceptional rift was seen around II:300 deg., where it spread whole width of the belt and no central component was seen. A few dark portions began to emerge along north of central component, and north component was broken up by some white areas. These would grow into array of barges and white spots (notches) in the near future. It is seemed that appearance of such features indicates that NEB cycle has entered next stage. Strongly bluish festoons and dark portions on NEBs edge were observed this apparition too, but it seemed to be fewer than in previous apparition.

SEB was characterized by bluish north component broken up irregular white spots like as last apparition. The belt itself was almost double, and SEBZ was generally quiet with a few reddish elongate spots at boundary between SEBZ and SEBs, except for active region following RS described later. On south edge, many projections (dark spots), which probably derived from SEBs jetstream activity, were observed. Following RS, activity of white spots was seen up to about II:160 deg., extending about 20 deg. against last month, since new activity of white spots began about Nov. 9 according to Einaga. Miyazaki indicated that this region was almost colorless, while NEB and main SEB had reddish tint.

RS was at II:100.7 deg. (Nov. 28, Miyazaki), with prominently orangish color but not so darker as in last apparition. It had faint arch on its southern border with short streak on preceding side, but there was no sign to be drawn by LEBS (BA) as in STr. Dislocation frequently observed in 1980s. It seems that the formation of arch and streak suggests that SEBs jetstream spots were colliding with RS in succession. BA was at II:29.2 deg. (Nov. 30, Einaga). It was easily distinguishable by small aperture, because it was prominent large oval. STB was broad and dark between BA and RS, following which it became tail-like streak shifting southward and reaching to about II:160 deg., while only faint STBn could be seen in other longitudes. Though the position of these features had changed against other System II markings like RS etc., the whole structure remained almost unchanged as in last apparition. SSTB was seen as prominent broad belt between II:350 and 200 deg., within which 4 long-lived white spots were observed following II:110 deg. On the other hand, SSTB widely divided into two components, and different designation should be given for each component.

NTB was invisible all round the planet. Akutsu, Fukui, Einaga and Ikemura took images by Methane absorption band, which could find white spot first, when NTBs jetstream outbreak (North Temperate Current-C) took place. But no spot can be seen on their images at this moment. NNTB was seen as south edge of north polar shading, but it was fragmentary and irregular. Though numerous jetstream spots were observed on NNTBs edge in previous apparition, those had not been detected, yet.

(2) Saturn

Saturn is in good period for observation, observation hours shifting to midnight from early morning. This apparition, Saturnian observations have rapidly increased in number, because it is attracting considerable attention not only by Cassini spacecraft but also by activities of white spots. This month, we have received observations listed below.

Appearance of white spots on Saturnian surface was observed twice this month, too. First spot appeared on Nov. 6, when Ikemura, Takimoto and Yunoki observed. According to Ikemura, white spot was in SEBZ at I:101 deg., in longitude and -24 deg. in latitude. It spanned about one-third of SEB but less brightness, and could not be traced after then.

Second one was detected by Hirabayashi on Nov. 22 at I:160 deg. It was small but distinct spot in SEBZ tangential to SEB north component, followed by somewhat disturbed region up to I:200 deg., where SEBn swelled a little, and festoon-like marking lying across SEBZ was seen at I:218 deg. on Fukui's image taken on the same day. This spot was traced through November, and images on Nov. 30 by Yunoki and Einaga showed the spot. Recent SEB had been fading southern half. Whole aspect of the region of white spot followed by dark markings observed this month resembled those of SEB Disturbance on Jupiter though much lower contrast. It is notable how long this activity will persist and whether aspect of SEB will show any changes.

As inclination of the ring plane has been decreasing, apparent minor axis of the ring has become a little shorter than that of Saturn's body this apparition. Though Saturn's body was invisible north of ring A in November, because it was obscured by shadow of ring A, some high resolution images showed very dim body there. Hirabayashi inferred that this fact was because ring A was translucent and shadow of the ring A was not perfectly black. According to Cassini's images which were taken from large phase angle proved above inference, showing that shadow of ring A was not so dark as that of ring B. Also, he noted that a part of ring A crossing immediately in front of Saturn's body was somewhat lighter than the rest, and pointed out that this might be because sunlight passed through Cassini's division shone the body in the back of ring A (this month, Ds was nearly 2 deg. greater than De, and the position of Saturn's body shone by sunlight deviated northward from Cassini's division). This phenomenon can be confirmed by some other images, and strongly suggests that ring A is translucent.

(December 10, K. Horikawa)

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