May 19, 1997

The following message was received from John Rogers concerning a bright cloud system that is located within the STrZ and, like the smaller eddies that became entrapped in the Red Spot during the Voyager encounters, this system should have an anticyclonic circulation. It should sweep around the north side, possibly become entrained in the eastward flow as it is carried around to the westward side of the Red Spot. In the Voyager time sequence, when the eddy entered the eastward flow to the south of the Red Spot as it moved past the south-eastern quadrant, material was swept into the collar surrounding the Red Spot. There is a possibility that the Red Spot will appear as a GIANT WHITE OVAL.

In addition Don Parker has submitted an excellent series of observations from 15 May.

Reta Beebe

Date: Tue, 13 May 1997 11:33:07 +0100 (BST)
From: John Rogers

An unprecedented collision has just begun between the Great Red Spot and a long-lived white oval in the STropZ. This conspicuous anticyclonic white oval has been tracked since 1987, and is the most substantial such feature ever to encounter the GRS. According to visible-light CCD images taken by Isao Miyazaki on May 12, it has just encountered the preceding end of the GRS and is becoming disturbed. His images on April 11 had shown the oval and the GRS were still separated by 8 degrees, so it seems that the two circulations have begun to interact rather suddenly.

Intensive observations of this collision would be worthwhile. As it is unprecedented, I can only guess what will happen and how long it will take. It may proceed like the interactions of SEBs jetstream spots with the GRS in Voyager imagery, except that this spot has been much more substantial and long-lived and slow-moving. The white oval may be drawn quickly to the north of the GRS, perhaps in the next week or two, and the GRS could suffer significant disruption.

-- John Rogers, BAA, May 13.

From: Glenn Orton Tue May 13 09:18 MDT 1997
Subject: major interaction between GRS and a large STrZ white oval, earlier predicted by John Rogers


The collision is happening NOW! Isao Miyazaki just sent these images, showing the GRS with the STropZ white oval already being drawn into the interaction. So I would recommend that the GRS itself (including the p. end) be covered as much as possible by Galileo at C9 -- and also in any images you can get from Mauna Kea.

Miyazaki's images were taken yesterday (May 12) so your imagery on May 4-10 should show the beginnings of the encounter. No measurements yet, but I guess the white oval may be drawn quickly to the north of the GRS, perhaps in the next week or two. It may proceed like the interactions of SEBs jetstream spots with the GRS in Voyager imagery, except that this spot has been much more substantial and long-lived and slow-moving, so I can only guess how long the interaction may last; the GRS could suffer significant disruption.

The new images also show the prominent barge still present N of the GRS, and white ovals ('portholes') in the NEBn, as expected. They should be still around in November for E11.

Re the cyclonic turbulent area f. the GRS: Yes, it's an important area to cover -- especially the f. end where the white spots are most likely to develop. But I don't yet have images to establish the longitude of this f. end this year. (Since you are now getting 'visible' images from the UH88 on Mauna Kea, I expect you know already!)

-- John.

From: Isao Miyazaki
To: John Rogers
Subject: newest images of STrZ white spot

Dear John,

I send you newest images of the STrZ white spot, which were taken this morning.

It is located just in front of P.end of the Red Spot. I am going to send you the longitude data of it within a few days.

*B&W image(Integrated Light images)
12 May 1997, 20h18m21s, 268.9(I) 37.9(II) 23.3(III),
Exp:0.38s, NR400 filter

*TriColor Image
12 May 1997, 20h15m36s-16m36s, 267.2-267.8(I) 36.3-36.9(II)
21.6-22.2(III), Exp:R60+NR400(0.90s),PO1+NR400(1.40s),

40cm Newtonian, LynxxPC

Isao MiyazakiB!!J 12 May, 1997

From Pierre Drossart Thu May 15 09:16 MDT 1997
Date: Thu, 15 May 1997 17:22:14 +0002
Subject: IJW observations of Jupiter
To: Reta Beebe

Dear Reta,

This message concerns the IJW joint observations, to mention that I have now the schedule of ISO observations of Jupiter; these observations concern the North and South polar regions as well as the equatorial regions, at several longitudes, and are devoted to a search for hydrocarbon emissions related to upper stratospheric heating. Jupiter observers having observations during this time range can contact me ( to possibly prepare a coordination in data reduction in case of simultaneous observations. Most wanted observations are H3+ imaging or UV imaging from space to have a knowledge of the Jupiter auroral activity at time of ISO observations.

This message is sent to auroral IJW team also. Sorry for the short notice, the schedule has been decided very recently...

Jupiter North and South regions from 25 May 6:32 to 7:26 UT
Jupiter equator from 26 May 1:05 to 4:43 UT (contiguous)
Jupiter North and South from 26 May 6:23 to 7:00 UT, 8:57 to 10:33 UT