|September 30, 1999 07:58 UT|
Instrument: 10-inch Starfinder
Apparent diameter: 48"
The seeing is quite good and details still crisp at 388X, the magnification at which the sketch at left was made in the 10-inch. I am able to discern the four Galilean satellites as disks for extended periods. Ganymede stands poised to begin a transit of the South Polar Region (SPR). The transit begins along the following (West) limb at -70 degrees at 08:00 UT. Any degree of unsteadiness creeping into the image is minimal. The seeing may not be perfect but definitely is among the handful of really good nights we get this time of year.
The Great Red Spot (GRS) is about an hour past the central meridian (CM), appearing elongated with a dark border, light colored interior and orange oval just inside the southern border. The South Equatorial Belt (SEB) displays quite a number of ovals and disturbances following the GRS. This gives the following section of the SEB a lighter tone than the preceding section. The largest of the disturbances remind me of squared teardrops. A string of four such features is clearly visible within the SEB beginning immediately northwest of the GRS hollow. This string extends westward toward the following limb. After about 20 degrees longitude, the disturbances become smaller and are positioned closer the to the southern border of the SEB. The major disturbances appear to diminish about 40 degrees in longitude from the GRS.
The South Tropical Zone (STrZ) separates the GRS from the South Temperate Belt (STB). The STB curves around the GRS's southern most extent. Three white ovals, two large ones flanking a smaller oval, are visible within the STB immediately following the GRS. These ovals are right along the CM. Two smaller ovals are visible within the STB further along toward the following limb. The SPR has an even gray cast from the STB to -70 degrees latitude. A darker gray pervades from here to the pole.
The South Temperate Belt (STB) is seen across the South Tropical Zone (STrZ) from the SEB. A small, dark knot is visible in the STB at a Sys II longitude of 20 degrees. The STB defines the northern extent of the gray hued South Polar Region (SPR). A narrow dark belt is visible within the gray South Polar Region (SPR). This belt is at -50 degrees latitude, the same latitude as the one observed September 25, 1999 at 06:35 UT. The Sys II CM of that observation was 5 degrees so Jupiter was presenting essentially the same SPR as is described here. This belt is located about 10 degrees south of the South South Temperate Belt (SSTB) observed just two hours earlier.
The North Equatorial Belt (NEB) features several festoons and a column along its southern edge. The festoons angle to the southwest and connect to the Equatorial Belt (EB). The first festoon is located at the Sys I longitude of 95 degrees, the second at a Sys I longitude of 130 degrees and the third at 170 degrees. The EB is noticeably darker where these festoons connect. The single column stands at a Sys I longitude of 135 degrees. Two rifts are visible within the NEB. These give the NEB a slightly braided appearance. The first begins along the southern edge of the NEB at a Sys I longitude of 105 degrees, angles to the northwest and terminates at Sys II longitude of 95 degrees along the northern edge of the NEB. The second also connects the NEB borders, extending from a Sys I longitude of 130 degrees to a Sys II longitude of 135 degrees along the NEB southern border.
A dark, lumpy North Temperate Belt (NTB) is visible across the North Tropical Zone (NTrZ) from the NEB. The North Temperate Zone (NTZ) has a subtle gray cast. The North North Temperate Belt (NNTB) is visible bordering the NTZ to the north. The North Polar Region (NPR) has a slightly heavier gray hue than the NTZ.
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Revised: February 2, 2002 [WDF]