This month, sudden activity began in SEB. On Dec. 18, Einaga caught a large white oval in SEB at about II:350 deg. It became two ovals on Dec. 25, and activity was expanding. According to Einaga's measurement, these ovals were at II:337.2 deg. and II:347.0 deg. respectively. Of the two, preceding oval was at a little lower latitude, and bluish SEBn was prominent on either side of the ovals. Since these are typical aspect of early stage of mid-SEB outbreak, new activity of mid-SEB outbreak must have begun from II:350 deg.

Mid-SEB outbreak is known as activity of white clouds which suddenly appear within SEB. When it happens, prominent white spots are formed one after another at a certain longitude, and they prograde at much faster rate relative to System II. Mid-SEB outbreaks were observed repeatedly in 1980s, and latest one took place in Sep. 2003 having source region at II:190 deg. Though most outbreaks started in the hemisphere following RS, this activity began in the opposite hemisphere, since source region of this activity is +240 deg. in longitude away from RS. Similar instance was observed in 1998, when the outbreak showed more intense and longer activity than previous mid-SEB outbreak. The region of mid-SEB outbreak will rapidly expand longitudinally, forming disturbed light band in SEBZ, as leading edge of outbreak will prograde at about -3.5 deg./day, while source region will be almost stationary.

RS was at II:107 deg., and faint and diffuse outline made it difficult to separate from SEB, though reddish. In SEB following RS, long light band extended to about II:180 deg., where a bright spot was seen in Fukui's image on Dec. 19. BA was at about II:210 deg. It seemed that it became a little smaller than that in last apparition, but its surroundings remained almost unchanged. Following BA, dark STB was seen up to about II:300 deg., and from there SSTB was prominent instead. On the other side of BA, Fukui's image on Dec. 19 showed a chain of dark spots similar to those in last apparition. It indicates that outbreak of STBn prograding jetstream is still going on.

Much dark and light portions could be seen in NEB even in poor seeing. These were mainly due to rifts and dark / white spots in northern half of the belt. North of NEB was almost featureless. NTB was absent at all longitude, and NNTB was also faint in most longitude, only being seen as south edge of NPR shading.

(2) Saturn

Saturn is retrograding in Cancer, being in good period for observation. Since it is passing by M44, it is possible that we watch them together in the same view, using finder with low magnification. Closest approach to M44 will be the end of January, when they will be a suitable target for observation apart from Saturn itself. This month, we have received observations listed below. In addition, three set of images of Saturn and its satellites were sent by Takimoto.

Saturn was still quiet, and no spot was seen this month. But it was possible that low contrast features might be overlooked due to poor condition, because there was information about small spots according to high resolution images by foreign observers. Recent Saturnian surface is generally quiet, though white spots and dark spots had frequently been observed in previous apparition. This fact may indicate that Saturn's activity has shifted into quiet term.

Several images at specific wavelength using filter were reported. Red or infrared images showed light band surrounding SPR. Though, at continuum light, this latitude was seen as dusky region extending from SPR, it indicated that reddish tint in last apparition still remained in fact. Yunoki pointed out that EZ was dark in UV images apart from other wavelengths, and similar feature could be found in Pellier's images.

(January 11, K. Horikawa)

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