| Observer | Location | Telescope | Images/Drawings | |
|---|---|---|---|---|
| Akutsu, Tomio | (Philippines) | 35cm SCT | 76 | images |
| Asada, Hideto | (Kyoto, Japan) | 31cm Refl. | 24 | images, 1 map |
| Carvalho, Fabio | (Brazil) | 25cm Refl. | 2 | images |
| Einaga, Hideo | (Hyogo, Japan) | 30cm Refl. | 29 | images, 1 map |
| Fukui, Hideto | (Shizuoka, Japan) | 35cm SCT. | 4 | images |
| Go, Christopher | (Philippines) | 28cm SCT | 30 | images |
| Horikawa, Kuniaki | (Yokohama, Japan) | 16cm Refl. | 10 | drawings |
| Kumamori, Teruaki | (Osaka, Japan) | 20cm Refl. | 18 | images |
| Mishina, Toshiroh | (Yokohama, Japan) | 20cm Refl. | 1 | image |
| Oyamada, Hiroyuki | (Kanagawa, Japan) | 20cm Refl. | 2 | images |
| Wesley, Anthony | (Australia) | 33cm Refl. | 9 | images |
| Yoneyama, Seiichi | (Yokohama, Japan) | 20cm Refl. | 6 | images |
The new activity in SEB preceding RS, started in March, believed to be mid-SEB outbreak was steadily expanded eastward, and p. end of the region reached close to II:330 deg. at the end of April. Main part of the activity was in II:35-75 deg., where disturbed light band typical of outbreak was formed, though few conspicuous spots were seen. SEBn was also irregular preceding the region without violent activity.
On Mar. 21, Go's image showed that bright spot emerged within SEB at about II:255 deg. Since the spot extended eastward, forming new active region similar to the outbreak mentioned above, another mid-SEB outbreak may have arisen from II:255 deg. It is the first time since 1985 that two mid-SEB outbreaks took place simultaneously. In the second half of April, the whole region of outbreak had exceeded 30 deg. in length, containing large bright ovals near source region. But the p. end of outbreak was not able to identify, since it merged into pre-existing active sector of SEBZ.
A dark ring on SEBs edge, which was expected to collide with RS, reached the p. end of RS bay in early April. Though the spot halted for a few days at the p. end of RS bay, it began to enter RS bay along north edge from Apr. 9. The last observation was made on Apr. 11, when it was a little east from the center of RS bay. On Apr. 18, a white streak extended eastward along SEBZ from the center of RS bay, where a bright rift broke n. edge of the bay. Therefore, it seems that the dark ring was swallowed up by RS, orbiting round its rim, as expected. RS itself, which was at II:124.3 deg. (Apr. 18, Akutsu), remained unchanged as reddish oval, but short bluish streak emerged according to images on Apr. 30.
On NEBn edge, plenty of barges and white spots were formed. All round the planet, 8 barges and 6 white spots were observed, but there may be more spots, because most white spots were difficult to see, exposing into NTrZ. Long-lived oval WSZ was at II:339.0 deg. (Apr. 10, Wesley). It was larger than other spots, and formed distinct bay on NEBn edge. According to Iga, two small white spots preceding WSZ rapidly approached each other, and finally merged on Apr. 10.
Two anticyclonic rings in STrZ which may have derived from STrD in last year were conspicuous this month too. They could be called Little Red Spot (LRS), since their reddish aspects and characteristics were similar to RS and LEBS. Of the two LRSs, preceding one was at II:161.1 deg. (Apr. 30, Go), being approaching RS together with BA which was at II:153.8 deg. (Apr. 30, Go). When they prograde as they are, three anticyclonic red ovals will gather late June. In the past, anticyclonic ovals in STrZ encountered RS repeatedly, when they orbited round its rim and were swallowed up, like dark ring described above. But it is difficult to expect what will take place this time, since it is the first case that anticyclonic oval encounters RS from the west, in contrast to all previous encounters being from the east. So, observer should pay attention to around RS from late June to July. The other LRS was at II:218.7 deg. (Apr. 21, Go).
(2) Saturn
Saturn was retrograding in Lao, and was in good period for observation. It was a suitable target to enjoy the view, since it was close to Regulus. This month, we received observations listed below.
| Observer | Location | Telescope | Images/Drawings | |
|---|---|---|---|---|
| Akutsu, Hiroaki | (Hokkaido, Japan) | 28cm Refl. | 7 | images |
| Einaga, Hideo | (Hyogo, Japan) | 30cm Refl. | 1 | image |
| Go, Christopher | (Philippines) | 28cm SCT | 4 | images, 1 animation |
| Ikemura, Toshihiko | (Nagoya, Japan) | 38cm Refl. | 1 | image |
| Kanno, Seiichi | (Yamagata, Japan) | 25cm Refl. | 2 | images |
| Kazemoto, Akira | (Kyoto, Japan) | 31cm Refl. | 1 | image |
| Kumamori, Teruaki | (Osaka, Japan) | 20cm Refl. | 4 | images, 1 animation |
| Mishina, Toshiroh | (Yokohama, Japan) | 20cm Refl. | 2 | images |
| Nakai, Kenji | (Hiroshima, Japan) | 25cm MCT | 4 | images |
| Takimoto, Ikuo | (Kagawa, Japan) | 31cm Refl. | 25 | images, 1 animation |
| Tatum, Randy | (USA) | 25cm Refl. | 2 | images |
| Tomita, Yasuaki | (Gunma, Japan) | 25cm Refl. | 1 | image |
| Tyler, Dave | (USA) | 28cm SCT | 44 | images |
| Yunoki, Kenkichi | (Osaka, Japan) | 26cm Refl. | 67 | images |
| Yoneyama, Seiichi | (Yokohama, Japan) | 20cm Refl. | 11 | images |
Second white spot on STBn edge (WS2) emerged in March was outstanding this month too. It was evident even in moderate-resolution images due to its brightness. It had a retrograding motion like the first spot (WS1), and in Yunoki's image on Apr. 27, it was at III:297.7 deg., having retrograded 20 deg. from original longitude. Drift rate during this period was +0.45 deg./day, which was larger than WS1. On the other hand, WS1 was faintly seen at around III:320 deg., though it seemed that it had disappeared in March.
In Tyler's image on Apr. 10 and Yunoki's image on Apr. 21, white spots were observed within SEB. They were at around III:180 deg. and III:105 deg, respectively, but they could not be confirmed in other images.
(May 15, K. Horikawa)
(Translated on October 27)
[Fig.1] Cylindrical map of Jupiter |
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| Created by Yuichi Iga from images between Apr. 8 and Apr. 10. |