INTERNATIONAL JUPITER WATCH NEWSLETTER

Reta Beebe
rbeebe@nmsu.edu
FAX 505-646-1938

Please do supply a prediction for November, just as a verification of what we're doing. We have a meeting this afternoon of a larger group of the Atmospheres Working Group to run over this, if you are still awake and "on line".
glenn

Here are updated longitudes (all System III) for the dark 'barges' and associated white 'portholes' in the NEB. Longitudes for most spots have been measured from Miyazaki's and Parker's images up to June 3 or 21, and from Pic du Midi images taken by Jean Lecacheux and colleagues up to July 9/10. They agree with the HST longitudes you quoted. This list supercedes my previous one, and the numbering of the spots from 9 onwards has been changed. White spots 2 and 3 on my previous list merged in mid-June, and 3b is the successor.

The largest and best-observed barge is no.4, recently at the longitude of the GRS; it is 12 deg. long. Numbers 6,8,11,13, are also good targets as they are very dark though rather small.

If you are targetting one of these barges at E11, it would be very desirable to extend imaging up to 26 deg.N, in the hope that one of the NTBs jetstream spots (dark anticyclonic spots at 23.6 deg.N, moving at DL3

-- John Rogers (BAA), 1997 July 15.

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NEB barges and portholes: System III longitudes, 1997.
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Column 2: DS = dark spot at 16 deg.N (cyclonic 'barge'), WS = white spot at 19 deg.N (anticyclonic 'porthole').
Column 3: DL3 = drift in System III (degrees per month).
Column 4: L3 on 1997 July 10.
Column 5: L3 predicted for 1997 Nov. 6.
(*Spots 3b,6,8,9,10 have only been observed over short intervals, June 21 - July 9. Drifts appear to be close to DL3 = +4 (+/- 4) deg/month, so this value has been assumed for all of them.)

	Description	DL3	L3(July 10)	L3(Nov.6)
1.	DS (small barge)	+6	353	17
2.	WS (merged with no.3)
3b.	WS	(+4)*	12	28
4.	DS (best barge)	+1	42	46
5.	WS	+3.5	92	106
6.	DS (barge)	(+4)*	131	147
7.	WS	+4	141	157
8.	DS (barge)	(+4)*	162	178
9.	WS	(+4)*	191	207
10.	WS	(+4)*	219	235
11.	DS (barge)	+6	275	299
12.	WS	+5.5	283	305
13.	DS (barge)	+4.5	291	309

Here's an update from Yuichi Iga on the NTBs jetstream spot outbreak.
-- John.

---------- Forwarded message ----------
From: Yuichi Iga (iga@kk-system.co.jp)
Subject: North Temperate Current-C of NTrZ

Dear Professor John Rogers,

I reported that a FAST moving dark spot of North Tropical Zone was probable to belong to the North Temperate Current-C(NT Current-C). I tried to analyze this feature and measure the longitude of all dark spots of NTrZ again. I used 28 sets of CCD images of Pic du Midi(April 2 to July 10), 22 sets of CCD images of H.Asada(April 12 to July 5) and 4 sets of CCD images of K.Okuda(May 17 to June 13).

I detected six dark spots of the NTrZ which have the mean rotation period of 9h49m8.6s. These are distinctly belonged to NT Current-C. The following table shows the rotation period and the drift relative to System I as a result of least square fitting calculation.

SPOT-1	9h49m12.338s	-57.86deg./month	N=22
SPOT-2	9h49m10.566s	-59.18deg./month	N= 7
SPOT-3	9h49m 8.102s	-61.02deg./month	N= 5
SPOT-4	9h49m 4.582s	-63.65deg./month	N=10
SPOT-5	9h49m 1.149s	-66.22deg./month	N= 8
SPOT-6	9h49m14.644s	-56.14deg./month	N= 5
Average	9h49m 8.564s	-60.67deg./month	N=57

The first dark spot named SPOT-1 was the most conspicuous one. The others named SPOT-2, SPOT-3,...,SPOT-6 were arranged in order of longitude after SPOT-1. It seemed that the SPOT-2 and SPOT-3 were the dark streaks extended about 10-20 degrees of longitude.

The drifts of six dark spots in NTrZ are clearly plotted on each straight lines. (black: dark spot, white: white spot, gray: not used)

Thank you so much that the staffs of Pic du Midi have continued to publish the CCD images on Web site vigorously.

Sincerely,
Yuichi Iga (ALPO-Japan, OAA)
E-Mail:iga@kk-system.co.jp

Here are some comments on the latest images sent by Isao Miyazaki (July 12) and Don Parker (July 14), both showing the GRS side.

• The NEB 'barges' and 'portholes' (my nos. 1,3b,4,5) are still distinct, as previously reported.
• Two NTBs jetstream spots (Yuichi Iga's nos. 4 & 5) can be seen moving past them at high speed.
• The curved blue-grey streak in the GRS appears to have shifted radially outwards between the two images! This would be most peculiar but, on closer inspection, I think this streak may be associated with a white strip, which is prominent in the north half of the GRS on July 12, and more drawn-out around the south half of the GRS on July 14. This would be just like the white strip which was orbiting round inside the GRS with a 6-day period during the Voyager encounters [pp.195-6 of 'The Giant Planet Jupiter']. The present blue-grey streak may be material (or clearing) variably spread around the white strip; but it had no analog during the Voyager encounters, and may well indicate that these features are relics of the white oval merger, especially the dark rim seen around the engulfed white oval on June 5-6.
• Although ovals BC, DE, FA are closer together than last year, and most of the ovals that were between them have disappeared, there is still a cyclonic spot between DE and FA; it is vivid red and so it may well be the 'morphing spot' that has kept us amused for several years.

-- John Rogers (BAA), 1997 July 16.