Two South Tropical Disturbances were remarkable features this month, too. STrD-1 was at II:350.0 deg. (Feb. 20, Einaga), and its p. end was prograding at -0.38 deg./day which was close to that we expected. At present, the most prominent feature was dark column at p. end, since following part of the disturbance faded and transformed into small step-down of SEBs edge as BA passed on the south. But whole length of STrD-1 has grown into almost 20 deg. in longitude. Einaga's image on Feb. 20 showed a small dark spot on STBn preceding STrD-1, and it implies that jetstream spot retrograding on SEBs was reflected by Circulating Current formed at p. end of STrD-1, but it may merely be one of STBn jetstream spots which observed recent apparitions, because SEB was quiet without retrograding spots this apparition. STrD-2 was observed as a dark broad column at II:218.7 deg. (Feb. 19, Kumamori). It was more prominent than STrD-1, since dark column had a width of 10-15 deg. in longitude. The drift rate of STrD-2 was -0.15 deg./day, much slower than STrD-1.

Main part of EZs disturbed region, which has darkened EZs very much, passed through north of RS around Feb. 20. This region contained large dark masses, and EZs was merged with SEBn up to I:300 deg., like one broad belt. There was a prominent rift breaking SEBn at the p. of the region, from which white cloud of SEBZ flew out, piling up as a large white oval. The p. end was at I:233.2 deg. (Feb. 21, Yoneyama), and retrograding at a rate of about +1.0 deg./day relative to System I. In other longitudes, EZs was also dusky, where yellowish zone was covered by bluish markings in some places.

RS was a solitary reddish oval. Though it was not so dark, it was outstanding because of clear outline and no dark surroundings. It retrograded a little from the early position of apparition, and was at II:116.3 deg. (Feb. 20, Kumamori). BA was still reddish at II:4.1 deg. (Feb. 20, Einaga), followed by STB dark segment about 50 deg. long. On the south of BA, SSTB was dark, containing an array of small white spots as well as last apparition. NEB was the only prominent belt in northern hemisphere, and NTB was still invisible. NNTB was somewhat diffuse belt but faint in longitude preceding RS. White spot WSZ on NEBn edge, which was noted by mergers with other spots last apparition, was still bright at II:83.2 deg. (Feb. 28, Kumamori).

(2) Saturn

Saturn was at opposition on Feb. 10 in Leo. Since it was in good period for observation, we received a lot of observations listed below, in spite of poor condition in winter.

The opposition effect of the ring, which is the annual event in recent years, was again observed this apparition. According to Einaga's chart which shows luminosity of the ring and Saturn's body, ring B had almost the same luminosity as that of body in the first half of February, and apparently surpassed on Feb. 10 and 11. Similar aspect of the ring could be seen in images by other observers, and seems to have continued during February.

On Saturn's body, several activities of white spot in SEB were reported this month, too. However, this kind of markings is difficult to confirm, since not only these are low contrast but also most observations are made by single observer. The observation which seems to be the most reliable was white spot at about III:250 deg. on Feb. 18, when images by Ikemura and Yunoki showed a round white spot in mid-SEB. But its contrast must have been very low, because it could not be seen in a little inferior condition. After all, the spot was probably short-lived, and no marking can be seen in images by Yunoki and Kazemoto on Feb. 26.

In addition to the above at SEB, some markings like white spots were observed by Vandebergh at about III:310 deg. (Feb. 4), Yunoki at about III:100 deg. (Feb. 20), and Yoneyama at about III:195 deg. (Feb. 26). But none of them was able to be confirmed in other images.

(March 10, K. Horikawa)

(Translated on May 23)

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