July 2, 1997

DPS Session Update, Reports of NTrZ Dark Spot, Comments by J. Rogers


July 31
Stratton 306
(Twenty Chimneys)
Reta Beebe
The topic of this meeting is to note new developments in Jovian Atmospheres and to make plans for collaborative efforts duing the coming year.

Subject: A Fast Moving Dark Spot in NTrop.Z

7-5-1011 Otowa-Noda-Cho, Yamashina-Ku,
Kyoto, Japan 706
June 30, 1997

I would like to report a fast moving Dark Spot in North Tropical Zone. Its Dark Spot has been quickly moved in a longitude system at about -9.25 degrees/day relative to System II. I think that the dark spot may be belonged to North Temperate Current-C(NT Curret-C).

I found a fast moving Dark Spot in following images through the Internet. The longitudes of this Dark Spot were roughly measured by the net mask of longitude-latitude.

Sys. II lon.
Date(UT)Pic du Midi AsadaMiyazakiOkuda
1997/06/28 306

The motions of this Dark Spot of NTrZ is plotted on a straight line. I have not analyzed other dark spots in this zone yet. But I think that the other dark spots have the same drift as this Dark Spot. Also I could not detect this Dark Spot in visual.


Pic du Midi CCD Images

1997/05/02 4h42.9
1997/05/11 4h58.7
1997/05/29 3h57.0
1997/06/02 6h19.3
1997/06/12 2h34.7
1997/06/24 28h50.3
1997/06/26 2h52.5
1997/06/28 1h36.2

Isao Miyazaki's CCD Image 1997/05/12 20h16m

ALPO Web Site:

Hideto Asada's CCD Images(305mm Newtonian, MUTOH CV-04 CCD Camera):
1997/05/10 19h24m
1997/05/26 18h56m
1997/06/06 19h03m
1997/06/13 18h27m
(*This site is only supported in Japanese.)

Kohji Okuda's CCD Images(250mm Newtonian, BITRAN BT-01 CCD Camera)
1997/05/17 18h07m
1997/06/06 18h26m
1997/06/13 18h10m
(*This site is only supported in Japanese.)


Yuichi Iga

From J.Rogers:

Here are a few comments on images up to June 6.

Recent Earth-based images of the GRS-WO collision.

In late May the WO appeared to stall just north-preceding the middle of the GRS, and to break up; and there was no distinct sign of it in Don Parker's images on June 3.
However images on June 5 (Scott Murrell, 755 nm, from the IJW web site) and June 6 (Isao Miyazaki, colour) show a striking bright spot just *north-following* the middle of the GRS, with a dark rim; this could well be the revived WO, still proceeding slowly round the GRS. I have seen no images since then!

The HST images from your IJW web site.

Please excuse me if these comments are out of date, as my web connection only permitted a partial look at your site, several weeks ago. In the comparison between an Earth-based image and a defocussed HST image, the Earth-based image was back to front.

Your full-resolution HST images, *higrs.* & *hibarge.*, are fascinating. Presumably these were taken near the end of April? Regarding the NEB barges that are so conspicuous in Earth-based images, they are visible in the *hibarge.* image, but at lower contrast than in Earth-based images (perhaps due to the filters used on HST?), and they are not fully separated and have ragged outlines. Presumably this is because they were still forming -- a very fortunate opportunity to follow them as they mature. More puzzling is the invisibility of the barge at the longitude of the GRS, in the *higrs.* image. This barge has been conspicuous and dark in all Earth-based images since April 11, and at all wavelengths from red to blue (see Parker images on May 15). But in the *higrs.* image, I note a small bright 'rift' draped around the position of the barge, so perhaps when the image was taken the barge was temporarily veiled by haze associated with the passage of this rift.

The Galileo images of the NEBs hotspot/projection.

Glad you caught such a fine NEBs hotspot/projection (and it even had a few puffy white clouds indicating slight plume activity). I have only seen the SSI and NIMS images released on June 5. However a press report at the time mentioned a 'weather map' of the hotspot (a NIMS water abundance map?), and dynamical evidence for convergence and downdraft in the hotspot (a wind vector map?). Are these maps now on the web site, or in press, or otherwise available?