Director: K. Horikawa, Secretary: Y. Iga
Jupiter was in opposition of this apparition on May 4, and has been in good period for observation. This month, we have received observations listed below. Though we have a spell of bad weather since early in May as if the rainy season already started, a large number of observations have been made from limited clear skies. Images by Friedman and Tyler were forwarded by Mars section as well as previous month. All Tyler's images were taken in April at Barbados.
| Observer | Location | Telescope | Images/Drawings | |
|---|---|---|---|---|
| Adachi, Makoto | (Otsu, Japan) | 31cm Refl. | 5 | drawings |
| Akutsu, Hiroaki | (Hokkaido, Japan) | 28cm Refl. | 7 | images |
| Akutsu, Tomio | (Philippines) | 28cm SCT | 16 | images |
| Asada, Hideto | (Kyoto, Japan) | 31cm Refl. | 23 | images |
| Einaga, Hideo | (Hyogo, Japan) | 25cm Refl. | 31 | images, 9 maps |
| Friedman, Alan | (USA) | 25cm MCT | 1 | image |
| Fukui, Hideto | (Shizuoka, Japan) | 25cm Refl. | 9 | images |
| Hatanaka, Akitoshi | (Mie, Japan) | 40cm Refl. | 12 | images |
| Hayashi, Toshio | (Kyoto, Japan) | 35cm SCT | 4 | images |
| Hirabayashi, Isamu | (Tokyo, Japan) | 25cm Refl. | 14 | images |
| Horikawa, Kuniaki | (Yokohama, Japan) | 16cm Refl. | 19 | drawings, 3 images |
| Ikemura, Toshihiko | (Nagoya, Japan) | 31cm Refl. | 28 | images |
| Kanno, Seiichi | (Yamagata, Japan) | 25cm Refl. | 14 | images |
| Kazemoto, Akira | (Kyoto, Japan) | 31cm Refl. | 13 | images, 1 animation |
| Kumamori, Teruaki | (Osaka, Japan) | 60cm Refl. | 19 | images |
| Mishina, Toshiroh | (Yokohama, Japan) | 20cm Refl. | 61 | images |
| Miyazaki, Isao | (Okinawa, Japan) | 40cm Refl. | 35 | images |
| Nakai, Kenji | (Hiroshima, Japan) | 25cm MCT | 4 | images |
| Narita, Hiroshi | (Kawasaki, Japan) | 20cm Refr. | 14 | drawings |
| Oyamada, Hiroyuki | (Hadano, Japan) | 20cm Refl. | 6 | images |
| Pellier, Christophe | (France) | 21cm MCT | 45 | images |
| Phillips, Jim | (USA) | 20cm Refr. | 7 | images |
| Takimoto, Ikuo | (Kagawa, Japan) | 31cm Refl. | 80 | images |
| Tatum, Randy | (USA) | 25cm Refl. | 19 | images |
| Tomita, Yasuaki | (Gunma, Japan) | 25cm Refl. | 3 | images |
| Tyler, Dave | (Barbados) | 28cm SCT | 20 | images |
| Yoneyama, Seiichi | (Yokohama, Japan) | 20cm Refl. | 14 | images |
| Yunoki, Kenkichi | (Osaka, Japan) | 20cm Refl. | 70 | images |
Mid-SEB outbreak was still active between RS and about II:270 deg. Though p. end of outbreak reached just following RS, post-GRS disturbance, which has contracted to 20-30 deg. in length, prevented the outbreak from still more prograding. On the other hand, widely lightened SEBZ preceding RS was notable. Northern half of SEB preceding RS was bluish with delicate white clouds aligning like tooth of comb, and its aspect extended more than 100 deg. in length beyond II:0 deg. Therefore, northern part of SEB was faint in almost all longitude, where SEB appeared as if the width of the belt had become half under poor condition. Such structure was already seen in March, but it spread over wide range in longitude and became light this month. Three possibilities were suggested for the origin of this light cloud as follows: 1. mid-SEB outbreak spread out preceding RS after it passed under visible cloud north of RS. 2. post-GRS disturbance was squeezed out preceding RS since it was crushed by mid-SEB outbreak. 3. white cloud from RS bay flowed into SEBZ preceding RS crossing over preceding shoulder of RS bay (Kumamori's image on May 20, etc.). However, it is uncertain at present which is the case.
BA coming into the limelight was immediately following RS at II:137.3 deg. (May 21, Ikemura). Inside original oval BA, pale reddish doughnut-shaped patch was still visible. Although redness of BA was clearly seen in almost images, in visual observation no redness of BA is reported at present. It will reach f. end of RS in July and start an encounter. Main belt segment of STB extended following BA to II:200 deg., and on south edge of the segment, a tiny spot were seen on just the middle. This spot seems to be identical with STZ spot which suddenly accelerated last July. RS was still surrounded by dark broad arch, but RS itself was seen inside, having clear redness. Dark arch on the south edge flowed out into STrZ, and formed short dark streak about 20 deg. in length. At the p. end of streak, there was a white spot, which was named Q by Rogers of BAA. It seems that Q is an anticyclonic spot similar to frequently observed spots in this latitude, and it will retrograde slowly and collide with RS. It will take place around solar conjunction, which is estimated from retrograding speed. RS still more retrograded and located at II:113.3 deg. (May 20, Miyazaki). SSTB was dark and broad almost all round the planet. Long-lived five white spots (A1-A5) was in the range of longitude between II:290 deg. and 50 deg., and cyclonic light region (FFR) was also seen between A2 and A3 and between A4 and A5. Because A2 and A3 were separating away this apparition, FFR between them elongated and transformed into faded section of the belt.
On NEBn edge, small white spots (portholes) became conspicuous. At all longitude, there were 9 portholes which became lighter and more prominent than before. On the other hand, some barges were able to be seen, but most of them were small and inconspicuous. Long-lived porthole called Z prograded to II:218.8 deg. (May 21, Einaga). It was bigger and brighter than other portholes, accordingly it began to expose into NTrZ. NTB disappeared and no sign of North Temperate Current-C was observed. Also, NNTB was faint, except for longitude exceeding II:300 deg. where dark belt segment was seen.
Observation condition of Saturn was becoming poor during May, gradually losing altitude in western sky after sunset. This month, we have received observations listed below.
| Observer | Location | Telescope | Images/Drawings | |
|---|---|---|---|---|
| Akutsu, Hiroaki | (Hokkaido, Japan) | 28cm Refl. | 1 | image |
| Ikemura, Toshihiko | (Nagoya, Japan) | 31cm Refl. | 1 | image |
| Takimoto, Ikuo | (Kagawa, Japan) | 31cm Refl. | 19 | images |
| Hatanaka, Akitoshi | (Mie, Japan) | 40cm Refl. | 2 | images |
| Fukui, Hideto | (Shizuoka, Japan) | 25cm Refl. | 2 | images |
| Yunoki, Kenkichi | (Osaka, Japan) | 20cm Refl. | 15 | images |
No marking like white spot was observed this month. As tilt of ring plane decreased, Saturn's body around North Pole came into view. In images by some observers, Saturn's body was clearly able to see through ring A. It indicated how ring A was thin.
As solar conjunction will come on Aug. 7, this apparition would substantially be over with start of rainy season. Next apparition, since tilt of ring plane will decrease more, North Polar Region will be easy to observe. We expect lively surface of Saturn, such as emerging bright spot observed in this apparition.
(June 9, K. Horikawa)
(Translated on October 23)