| Observer | Location | Telescope | Images/Drawings | |
|---|---|---|---|---|
| Akutsu, Tomio | (Philippines) | 28cm SCT | 4 | images |
| Einaga, Hideo | (Hyogo, Japan) | 25cm Refl. | 43 | images, 9 maps |
| Horikawa, Kuniaki | (Yokohama, Japan) | 16cm Refl. | 5 | drawings, 1 image |
| Mishina, Toshiroh | (Yokohama, Japan) | 20cm Refl. | 11 | images |
| Takimoto, Ikuo | (Kagawa, Japan) | 31cm Refl. | 31 | images, 3 maps |
| Tomita, Yasuaki | (Gunma, Japan) | 25cm Refl. | 1 | image |
| Yoneyama, Seiichi | (Yokohama, Japan) | 20cm Refl. | 3 | images |
| Yunoki, Kenkichi | (Osaka, Japan) | 20cm Refl. | 10 | images |
Mid-SEB outbreak kept notable activity this month too. Source region of the outbreak which was at II:335 deg. early in January prograded to II:320 deg. at the end of the month, indicating faster prograding rate than before. New white spots continued to appear from source region, from which disturbed light band including white spots extended toward north-preceding direction. Light band contained prominent bright spots in some places, for example about II:280 deg. on Feb.1 and about II:270 and 300 deg. on Feb. 9 (Einaga). It seemed that leading edge of the outbreak was at about II:250 deg. on Feb. 18 (Tomita). Compared with about -2.0 deg./day estimated last month, its prograding rate slowed down. It would be due to ill-defined leading edge which tapered toward SEBn edge and faded away.
RS was surrounded by dark arch. RS itself was faint with diffuse outline though reddish. Because SEBs edge was disturbed with irregular humps and shadings predceding RS, it seemed that dark arch was formed by interaction between SEBs dark material and RS, but dark streak has not emerged from p. end of RS into STrZ yet. Following RS, post-GRS disturbance extended to about II: 180 deg., showing disturbed light band in SEBZ also in this sector. However, activity of white clouds inside light band was not as violent as region of mod-SEB outbreak, and aspect of f. end of the region acting as source of white spots was variable. Leading edge of mid-SEB outbreak was approaching f. end of post-GRS disturbance. It is interesting in what change will be seen in future.
This month, LEBS BA attracted attention by its reddish tint, which first pointed out by Christopher Go of Philippines. His image on Feb. 27 showed BA as distinct light oval with red-brown color, having concentric structure inside. In other images reported to our section, BA presented warm color against surrounding zones as well, and it was quite dim and indistinct due to low contrast. It is not the first time that LEBS become reddish. In 1991, when three ovals had not merged yet, Isao Miyazaki, the former director of the section, pointed out that the then DE wore reddish tint. Since LEBS is anticyclonic vortex similar to RS, though these are different in a scale, and these must have followed the same course of the origin and development, it is possible that BA has redness. However, it took long time that RS, which was originally discovered as Hollow, grew up to be the literal 'red oval'. It will be verified over a long term of years whether this change of BA is the beginning of true reddening or merely temporary event.
On NEBs edge, there were plenty of bluish plateaus with festoons, most of which were typical appearances extending long into EZ in this apparition. Main NEB was vivid reddish-brown, showing striking contrast against bluish s. edge. Several portholes were seen on n. edge of NEB. Long-lived white spot Z was larger than others and outstanding at about II:280 deg. Rogers (BAA) reported a merger of berges, but we failed to confirm this event from our observations.
(2) Saturn
Saturn just passed opposition and was in good period for observation. Since a bright spot appeared after a long quiet period, it attracted observers' attention very much. This month, we have received observations listed below.
| Observer | Location | Telescope | Images/Drawings | |
|---|---|---|---|---|
| Akutsu, Hiroaki | (Hokkaido, Japan) | 28cm Refl. | 6 | images |
| Akutsu, Tomio | (Philippines) | 28cm SCT | 6 | images |
| Einaga, Hideo | (Hyogo, Japan) | 25cm Refl. | 20 | images |
| Mishina, Toshiroh | (Yokohama, Japan) | 20cm Refl. | 22 | images |
| Nakai, Kenji | (Hiroshima, Japan) | 25cm MCT | 1 | image |
| Pellier, Christophe | (France) | 21cm MCT | 10 | images |
| Phillips, Jim | (USA) | 20cm Refr. | 30 | images, 1 animation |
| Takimoto, Ikuo | (Kagawa, Japan) | 31cm Refl. | 55 | images, 2 animations |
| Tomita, Yasuaki | (Gunma, Japan) | 25cm Refl. | 1 | image |
| Vandebergh, Ralf | (Netherlands) | 25cm Refl. | 9 | images, 5 animations |
| Yoneyama, Seiichi | (Yokohama, Japan) | 20cm Refl. | 6 | images |
| Yunoki, Kenkichi | (Osaka, Japan) | 20cm Refl. | 39 | images |
Bright spot on STBn edge appeared last month was still conspicuous this month. It became a little larger than that in initial stage, and was seen as white spot in STrZ under poor condition. According to T. Akutsu's image on Feb. 25, a strip of white cluod trailed out into STrZ following the spot just like a plume of Jupiter. But his other images in wavelengths of blue, red, infrared, and methane did not show the spot. Because in Yunoki's images using filters last month, the spot could be seen except for methane band, it may already have begun to decline.
The spot was at III:193.9 deg. in longitude and -41.8 deg. in latitude (Feb. 25, T. Akutsu), and retrograded over 20 deg. from its emergence. Its drift rate was as slow as +0.7 deg./day, 10h40m38s in rotation period, which was more than 1 minute longer than System III. The spot will be able to observe for the time being, as it still has enough contrast.
(March 8, K. Horikawa)
(Translated on July 12)
[Fig.1] Drift chart of white spot emerged on STB of Saturn |
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