As well as Einaga last month, Pellier also provided a map of full disk, which is helpful for understanding the whole status of Jupiter. The p. end of mid-SEB outbreak was approaching RS. It position was conjectured about II:145 deg. at end of April, though its precise position was hard to define. Current prograding speed was much less than -1 deg./day, which slowed down than before. It would be because that post-GRS disturbance between RS and mid-SEB outbreak stood in the way of advance. SEBn was much disturbed in the sector where outbreak contacted with post-GRS disturbance. The post-GRS disturbance was crushed to the south and has been contracted to about 30 deg. in length at the end of the month as mid-SEB outbreak prograded, though it extended to about II:190 deg. at the beginning of the apparition. On the other hand, the f. end of outbreak was slowly prograding at about II:300 deg. A chain of large and irregular white spots was seen inside of the outbreak, but a sector close to f. end was rather quiet. A step-up of SEBn at II:255 deg. (Apr. 28, Pellier) appeared to be the boundary of the two sectors.

RS was seen as white oval surrounded by dark arch and SEB, and whole aspect was perfect RS Hollow, though dark core was seen and redness remained inside. Preceding RS, short dark streak emerged from dark arch, and it was prominent between RS and STrZ white spot at about II:80 deg. The longitude of RS was II:109.2 deg. on Apr. 7 (Fukui). BA was seen as an oval with warm color at II:157.5 deg. (Apr. 7, Yunoki). It became easy to see, because it flanked by dark segment of STB, preceding of which darkened like a dark patch this month. High resolution images by Tyler showed reddish ring structure inside of BA. It is interesting aspect just like RS and Hollow.

In EZ, festoons became most conspicuous in recent years. According to Pellier's cylindrical map, there were 11-12 prominent festoons, all round the planet, and some of them accompanied plume-like bright spot on the root. EB was also dark and broad at all longitude. Its south edge was straight, while north edge was variable, being formed by the tips of long festoons. Since EZs was dull yellowish together, whole zone was dusky and low contrast with SEBn. Therefore, in some images under poor condition, the region from EB to southern SEB sometimes appeared to be single zone at longitude of mid-SEB outbreak where SEBn was faint.

In NEB, there were 5 barges and 8 portholes. Unlike other portholes, long-lived one called Z at about II:240 deg. was prograding at faster speed of -0.6 deg./day. It seemed that NEB, which had been broad since 2004, retreated a little from north edge, and the porthole mentioned above began to expose into NTrZ. NTB was invisible at all longitude, and from NEBn edge to NNTB was observed as single wide zone. But faint dusky bands were seen in some places at latitude of NTBn, and NTB on the north side was somewhat dusky. Although I wrote in the report of previous month that dark spots on NNTBs jetstream became fewer, Pellier's map showed plenty of tiny dark spots and projections on s. edge of the belt. It seems to indicate that jetstream activity was still going on.

(2) Saturn

Saturn passed stationary on Apr. 5, and turned to prograding motion. And then it was at eastern quadrature on Apr. 25, and has moved to west sky in evening. This month, we have received observations listed below. This year, we have more Dust and sandstorms, which was serious obstacle in observing Saturn especially for observers in the western part of Japan, because atmospheric transparency greatly influences imaging of Saturn whose surface has low luminosity.

White spot on STBn edge disappeared. The final appearance of the spot was on Apr. 1 and 5 in Vandebergh's extremely high contrast images, in which trace of the spot was barely seen, though it had already been invisible on normal images. It was a visible spot after a long absence, and was tracked for about two months since it appeared in the end of January. The next appearance of similar spot is strongly expected.

This month, Pellier observed white spots in SEB on Apr. 6 and 17. The spot of former date was at around III:0 deg., and the other one was at around III:275 def., but neither were tracked after then. Pellier imaged Saturn by equipping filters in several short wavelengths, and showed that NPR was lighter in shorter wavelengths, while other part of Saturn disk became darker due to haze. He suggested that seasonal variation of Saturn could be tracked from observation using such filters.

(May 11, K. Horikawa)

(Translated on October 18)

[Fig.1] Cylindrical map of Jupiter

Created by Christophe Pellier from his own images taken between Apr. 22 and 29

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