Director: K. Horikawa, Secretary: Y. Iga
Jupiter is high in the sky around midnight, and it is in good period for observation. As poor seeing days are dominant in winter, we must be careful not to miss infrequent good conditions. This month, we have received observations listed below.
| Observer | Location | Telescope | Images/Drawings | |
|---|---|---|---|---|
| Akutsu, Tomio | (Karasuyama, Japan) | 32cm Refl. | 46 | images |
| Einaga, Hideo | (Kasai, Japan) | 25cm Refl. | 53 | images |
| Fukui, Hideto | (Kyoto, Japan) | 25cm Refl. | 52 | images |
| Grafton, Ed | (USA) | 35cm SCT | 5 | images |
| Horikawa, Kuniaki | (Yokohama, Japan) | 16cm Refl. | 27 | drawings, 10 images |
| Iga, Yuichi | (Kyoto, Japan) | 28cm SCT | 5 | images |
| Ikemura, Toshihiko | (Nagoya, Japan) | 31cm Refl. | 6 | images |
| Kanno, Seiichi | (Kaminoyama, Japan) | 25cm Refl. | 3 | images |
| Kazemoto, Akira | (Kumiyama, Japan) | 31cm Refl. | 4 | images |
| Meiji Univ. | (Ashigara, Japan) | 21cm Refl. | 6 | imaegs |
| Mishina, Toshiroh | (Yokohama, Japan) | 20cm Refl. | 27 | images |
| Miyazaki, Isao | (Okinawa, Japan) | 40cm Refl. | 24 | images |
| Morita, Mitsuji | (Moriyama, Japan) | 20cm Refl. | 6 | images |
| Nakai, Kenji | (Hiroshima, Japan) | 25cm SCT | 4 | images |
| Narita, Hiroshi | (Kawasaki, Japan) | 20cm Refr. | 9 | drawings |
| Neichi, Mitsuyuki | (Aomori, Japan) | 25cm Refl. | 2 | images |
| Ota, Satoshi | (Okinawa, Japan) | 32cm Refl. | 5 | images |
| Sherrod, P. Clay | (USA) | 31cm SCT | 24 | images |
| Suzuki, Takashi | (Tokyo, Japan) | 18cm MCT | 5 | images |
| Yoneyama, Seiichi | (Yokohama, Japan) | 20cm Refl. | 7 | images |
| Yunoki, Kenkichi | (Sakai, Japan) | 20cm Refl. | 47 | images |
This month, Jovian surface was generally quiet, no significant change occurred. Dark arch and streak around RS formed in December was fading away, without developing considerably, as expected. Dark bluish arch surrounding south edge was still visible, while dark streak preceding RS almost faded away, remaining small dark patches at p. end of RS. RS itself had striking orange color, with small darker portion at center, and its northern edge was relatively clear. STB small dark spot was passing south of RS. It reached f. end of RS around Jan. 10, and just south on Jan. 27. RS was not influenced by passage of the spot, probably it would pass away without incident. The center of RS was at II:91.8 deg. (Jan. 27, Einaga), and almost constant during January.
Activity of mid-SEB outbreak still persisted, gradually declining down. In early January, a bright spot was seen at II:170 deg., but active region was contracting after then. On Jan. 27, its f. end was estimated around II:140 deg., but it was followed by disturbed light band with tiny white spots. It is possible that it will become active intermittently in the future.
BA was at II:170.0 deg. (Jan. 30, Miyazaki), very prominent as light oval surrounded by dark collar. Strongly bluish region following BA formed in December, probably cyclonic FFR (folded filamentary region), showed striking contrast against surroundings in the first half of the month. But gradually receding bluish color, it had been not distinguishable from surroundings by the end of the month. Moreover, both side STB also darkened connecting with STB dark segment following the feature, and dark STB was reformed between BA and II:280 deg., spanning about 100 deg. long. Following the segment, thin component could be seen along STBs edge extending to around II:340 deg.
EZ was slightly dusky in northern half, where it was apparently yellowish in CCD images. From NEBs edge, many prominent bluish festoons were seen. Most of them were accompanied by blue-gray plateau on NEBs edge, showing striking contrast against warm-color NEB itself. Vigorous rift activity was seen inside NEB. In early January, there were two major active regions, II:70-130 deg. and II:180-260 deg., where NEB was seen generally double. These sectors were prograding at much faster drift (about -4 deg./day) relative to II. Then former sector had faded away, while latter reached II:120-180 deg. by the end of the month.
Because NTB and NNTB were very faint, few markings were observed in northern hemisphere except for NEB. But tiny dark spots were scattered along NNTBs edge, prograding rapidly (about -2.5 deg./day) on NNTBs jetstream. As NTB was faint at all longitudes, it was ready for next outbreak of NTBs jetstream (North Temperate Current-C). It is necessary to pay high attention in every observation whether a brilliant spot or dark spot emerges on the latitude of NTBs edge.
Saturn has passed opposition on the New Year's Day, and it is in good period for observation. This month, we have received observations listed below.
| Observer | Location | Telescope | Images/Drawings | |
|---|---|---|---|---|
| Einaga, Hideo | (Kasai, Japan) | 25cm Refl. | 6 | images |
| Fukui, Hideto | (Kyoto, Japan) | 25cm Refl. | 5 | images |
| Grafton, Ed | (USA) | 35cm SCT | 8 | images |
| Ikemura, Toshihiko | (Nagoya, Japan) | 31cm Refl. | 17 | images |
| Kazemoto, Akira | (Kumiyama, Japan) | 31cm Refl. | 5 | images |
| Kumamori, Teruaki | (Sakai, Japan) | 60cm Refl. | 1 | image |
| Morita, Mitsuji | (Moriyama, Japan) | 20cm Refl. | 19 | images |
| Nakai, Kenji | (Hiroshima, Japan) | 25cm SCT | 8 | images |
| Neichi, Mitsuyuki | (Aomori, Japan) | 25cm Refl. | 3 | images |
| Ota, Satoshi | (Okinawa, Japan) | 32cm Refl. | 5 | images |
| Peach, Damian | (UK) | 30cm SCT | 48 | images |
| Pellier, Christophe | (France) | 18cm Refl. | 3 | images |
| Suzuki, Takashi | (Tokyo, Japan) | 18cm MCT | 1 | image |
| Yoneyama, Seiichi | (Yokohama, Japan) | 20cm Refl. | 5 | images |
| Yunoki, Kenkichi | (Sakai, Japan) | 20cm Refl. | 50 | images |
In Saturn, as had observed in last month, white and dark spots were found in STrZ and SEB, respectively. STrZ white spot was at about III:95 deg. on Jan. 20 taken by Grafton, and by Yunoki after one rotation of the planet. Though the spot had been relatively light and clear on Jan. 20, it was invisible in Ikemura's image taken on Jan. 29.
SEB dark spots were observed by Ikemura on Jan. 4, by Grafton on Jan. 14, and by Peach by Jan. 27. Ikemura's spot was a diffuse patch at about III:330 deg., and Peach's image showed similar one (about III:170 deg.). On the other hand, Grafton's spot were a tiny dark spot on the north edge of faded SEBs at about III:270 deg. It is unlikely that these spots were identical, according to these size and longitude. Also, another Ikemura's image taken on Jan. 29 showed a dusky patch on SEB at about III:100 deg.
Faded south component of SEB became still fainter, and it could not be seen at all in poor condition. Between STB and n. edge of SPR has blue-green tint showing impressive beautiful contrast against pale orange of SEB-STB.
(February 9, K. Horikawa)