Director: K. Horikawa, Secretary: Y. Iga
Jupiter passed western quadrature on Dec. 10, and it comes up in the east sky just after midnight. This month, we have received observations listed below.
| Observer | Location | Telescope | Images/Drawings | |
|---|---|---|---|---|
| Adachi, Makoto | (Otsu, Japan) | 31cm Refl. | 9 | drawings |
| Akutsu, Tomio | (Karasuyama, Japan) | 32cm Refl. | 36 | images |
| Colville, Brian | (Canada) | 30cm SCT | 7 | images |
| Einaga, Hideo | (Kasai, Japan) | 25cm Refl. | 47 | images |
| Fukui, Hideto | (Kyoto, Japan) | 25cm Refl. | 26 | images |
| Grafton, Ed | (USA) | 35cm SCT | 1 | image |
| Horikawa, Kuniaki | (Yokohama, Japan) | 16cm Refl. | 23 | drawings, 14 images |
| Ikemura, Toshihiko | (Nagoya, Japan) | 31cm Refl. | 6 | images |
| Kanno, Seiichi | (Kaminoyama, Japan) | 25cm Refl. | 1 | image |
| Kazemoto, Akira | (Kumiyama, Japan) | 31cm Refl. | 1 | image |
| Meiji Univ. | (Ashigara, Japan) | 21cm Refl. | 12 | imaegs |
| Mishina, Toshiroh | (Yokohama, Japan) | 20cm Refl. | 31 | images |
| Miyazaki, Isao | (Okinawa, Japan) | 40cm Refl. | 25 | images |
| Morita, Mitsuji | (Moriyama, Japan) | 20cm Refl. | 9 | images |
| Narita, Hiroshi | (Kawasaki, Japan) | 20cm Refr. | 14 | drawings |
| Neichi, Mitsuyuki | (Aomori, Japan) | 25cm Refl. | 4 | images |
| Ng, Eric | (Hong Kong) | 30cm Refl. | 13 | images |
| Ota, Satoshi | (Okinawa, Japan) | 32cm Refl. | 2 | images |
| Oyamada, Hiroyuki | (Hadano, Japan) | 20cm Refl. | 1 | image |
| Pellier, Christophe | (France) | 18cm Refl. | 8 | images |
| Sherrod, P. Clay | (USA) | 31cm SCT | 28 | images |
| Suzuki, Takashi | (Tokyo, Japan) | 18cm MCT | 4 | images |
| Yoneyama, Seiichi | (Yokohama, Japan) | 20cm Refl. | 9 | images |
| Yunoki, Kenkichi | (Sakai, Japan) | 20cm Refl. | 37 | images |
Activity of mid-SEB outbreak was still continuing in December. Prograding motion of its source had halted, and it stayed around II:170 deg. during the month. Though newly formed white spots near f. end located in mid-SEB, they gradually shifted northward as they prograded, lying light band alongside thin n. component of the belt between II:140 deg. and RS. It seemed that activity of the outbreak was declining, as light band was narrower and fewer prominent white spots than those in September and October.
Slight change took place in aspect of RS. Its southern edge was surrounded by dark arch, p. end of which extended into STrZ as dark streak about 20 deg. long. Probably, it would be arose as result of collisions of tiny jetstream spots retrograding on SEBs edge with RS, but detailed situation had not been observed. It is interesting how long the streak would develop preceding RS. Miyazaki suggested that the streak would not lengthen so long, because there was no STB white oval around, which would dominate STrZ activity preceding RS as White Ovals in 1970-80s. RS was at II:92.0 deg. (Dec. 29, Ng), nearly stationary. From following RS, STB dark spot was approaching, and it would reach f. end of RS soon.
BA was at II:187.4 deg. (Dec. 22, Yunoki), with no brightness and low-contrast. But dusky shading surrounding it kept it easy to see even by small aperture. Late December, it was seen as largest elongate oval in recent few years, having about 12 deg. long in Miyazaki's image taken on Dec. 29. Following BA, STB dark segment was approaching. Its p. end was at II:250 deg., and the region between them was complicate and variable. A large dark oval could be seen in STZ since October just preceding p. end of the segment. According to Miyazaki's image, it was reddish dark ring. In second half of December, bluish elongate region about 20 deg. long developed about II:210 deg., showing impressive contrast against warm color surroundings. It seemed to be FFR(folded filamentary region) with cyclonic circulation.
In northern hemisphere, several tiny dark spots are seen along faded NNTBs edge. These were NNTBs jetstream spots rapidly prograding relative to II (about -2.5 deg./day), as seen in previous apparition.
New Year's Day of 2004 was the date of opposition in this apparition, and it is in good period for observation. This month, we have received observations listed below.
| Observer | Location | Telescope | Images/Drawings | |
|---|---|---|---|---|
| Akutsu, Tomio | (Karasuyama, Japan) | 32cm Refl. | 13 | images |
| Akutsu, Hiroaki | (Asahikawa, Japan) | 28cm Refl. | 4 | images |
| Einaga, Hideo | (Kasai, Japan) | 25cm Refl. | 36 | images |
| Fukui, Hideto | (Kyoto, Japan) | 25cm Refl. | 4 | images |
| Grafton, Ed | (USA) | 35cm SCT | 5 | images |
| Ikemura, Toshihiko | (Nagoya, Japan) | 31cm Refl. | 26 | images |
| Kazemoto, Akira | (Kumiyama, Japan) | 31cm Refl. | 5 | images |
| Meiji Univ. | (Ashigara, Japan) | 21cm Refl. | 2 | imaegs |
| Mishina, Toshiroh | (Yokohama, Japan) | 20cm Refl. | 2 | images |
| Morita, Mitsuji | (Moriyama, Japan) | 20cm Refl. | 13 | images |
| Nakai, Kenji | (Hiroshima, Japan) | 25cm SCT | 6 | images |
| Neichi, Mitsuyuki | (Aomori, Japan) | 25cm Refl. | 3 | images |
| Ng, Eric | (Hong Kong) | 30cm Refl. | 7 | images |
| Ota, Satoshi | (Okinawa, Japan) | 32cm Refl. | 2 | images |
| Peach, Damian | (UK) | 30cm SCT | 2 | images |
| Suzuki, Takashi | (Tokyo, Japan) | 18cm MCT | 1 | image |
| Yoneyama, Seiichi | (Yokohama, Japan) | 20cm Refl. | 1 | image |
| Yunoki, Kenkichi | (Sakai, Japan) | 20cm Refl. | 54 | images |
On Saturn, emergence of spots were observed this month, too. On Dec. 12, Ikemura detected a fairly prominent white spot in STrZ at around III:90 deg. It could be seen in several images until mid December, which had become faint by end of the month.
Grafton, Ikemura Morita, and Peach also observed other white spots in mid-SEB and southern EZ, but insufficient observations prevented from checking identity of these spots.
(January 10, K. Horikawa)