LtE in CMO #282

From Edward Arnold GRAFTON



@ . . . . . . . .Date: Tue, 4 Nov 2003 15:59:23 -0600 (CST)

Subject: Saturn November 4th 2003

 

Hi Saturn Observers

 

Here is an observation from November 4th 2003. There looks to be a small low contrast spot that is near the CM on the 8:48 UT image. The latitude looks to be about -50 South unlike the usual interlopers at -42 South. The sky was clear with ground fog moving through at different densities, the transparency was poor to good 3-8/10, and seeing was very good 8/10. Light 1 mph South wind and heavy dew with moister dripping from the surrounding foliage. The weather was mild with the temperatures in upper 60s F.

 

Saturn image: http://www.ghg.net/egrafton/11-04-03.jpg

 

††††††† Ed Grafton, Houston Texas, ST5C CCD and a 14 inch f/11 Celestron SCT

††††††† Barlow Projection to f/27 aprox .21 arc seconds per pixel.

††††††† Image data:

††††† ††††††††††BLUE††† + IR rejection, 1second, Edmunds filter

††††††††††††††† GREEN†† + IR rejection, .8seconds, Edmunds filter

††††††††††††††† RED†††† + IR rejection,.6seconds, Edmunds filter

††††††††††††††† Clear filter,No IR.3seconds,Edmunds filter

††††††††††††††††††††††††††††††††††††††††††††††

@ . . . . . . . .Date: Wed, 5 Nov 2003 13:35:41 -0600 (CST)

Subject: Saturn November 5th 2003

 

Hi Saturn Observers

 

Here is an observation from November 5th 2003. The sky was clear, the transparency was very good 8/10, and seeing was very good to excellent 9/10. Light 2 mph SE wind and heavy dew. The weather was mild with the temperatures in upper 60s F.

 

Saturn image: http://www.ghg.net/egrafton/11-05-03.jpg

 

††††††† Ed Grafton, Houston Texas, ST5C CCD and a 14 inch f/11 Celestron SCT

††††††† Barlow Projection to f/27 aprox .21 arc seconds per pixel.

††††††† Image data:

††††††††††††††† BLUE††† + IR rejection, 1second, Edmunds filter

†††††††† †††††††GREEN†† + IR rejection, .8seconds, Edmunds filter

††††††††††††††† RED†††† + IR rejection,.6seconds, Edmunds filter

††††††††††††††† Clear filter,No IR.3seconds,Edmunds filter

 

@ . . . . . . . .Date: Thu, 6 Nov 2003 09:30:38 -0600 (CST)

Subject: Saturn November 6th 2003

 

Hi Saturn Observers

 

Here is an observation from November 6th 2003. There is a dark feature present to the South of the SEB and is near the CM on the 09:31 UT immge. It is not clear what this feature is but may be a cluster of unresolved dark spots or a barge like feature. The sky was clear with light fog, the transparency was fair to good 5-8/10, and seeing was very good to excellent 9/10. Light 1 mph S wind and heavy dew. The weather was mild with the temperatures in upper 60s F.

 

Saturn image: http://www.ghg.net/egrafton/11-06-03.jpg

 

††††††† Ed Grafton, Houston Texas, ST5C CCD and a 14 inch f/11 Celestron SCT

††††††† Barlow Projection to f/27 aprox .21 arc seconds per pixel.

††††††† Image data:

††††††††††††††† BLUE††† + IR rejection, 1second, Edmunds filter

††††††††††††††† GREEN†† + IR rejection, .8seconds, Edmunds filter

††††††††††††††† RED†††† + IR rejection,.6seconds, Edmunds filter

††††††††††††††† Clear filter,No IR.3seconds,Edmunds filter

 

@ . . . . . . . .Date: Thu, 6 Nov 2003 20:25:22 -0600 (CST)

Subject: Re: Saturn November 6th 2003

 

Hi Saturn Observers

 

The dark feature in the Saturn image of Nov. 6th is somewhat of a puzzle to me so I searched for an explanation. One possibility is that the dark feature is an eddy and the lighter area following it is left in it's wake. I found a Voyager 2 image that looked like it could be the same kind of feature as in the Nov. 6th image. The URL to the voyager 2 image is:

 

http://www.ghg.net/egrafton/vg2_p239.gif

 

Any other possible explanations would be interesting to hear.

 

@ . . . . . . . .Date: Fri, 7 Nov 2003 11:19:33 -0600 (CST)

Subject: Update: Saturn November 6th 2003

 

Hi Saturn Observers

 

Dr. Agustin Sanchez Lavega has sent along HST images that clearly shows the structure of the dark area and the following -29 degree white spot that has been well tracked by several observers. The dark area is most pronounced in the HST 555nm filtered image. The white spot has more of an amorphous structure in the 675nm HST image. These features also can be seen in the images on the 10/24 and 10/28 images that Damian Peach sent along. Please see Austin's comments below and the attached HST images and tracking graphic.

†††††††††††††††††††††

Dear Ed,

 

Here is an update of the motion of the spots at -29 deg, and an enlargement of one of them as captured by the HST at the highest possible resolution. Your dark spot on November 6 is at the edge of the small white spot (blue track in the figure).

 

Note that whereas the HST spot is "compact" and round in blue (filter 439 nm), it shows structure around it in the other filters. The spot is located in a weak anticyclonic flow (and probably it is an anticyclone), and southward (latitudes -35 deg) the HST images in blue-yellow show a belt with zonal texture. It is probably a cyclonic more turbulent region, to which your dark spot probably pertains.

 

I loose the observers list. Could you send this email to them?

 

Thanks a lot and good observations!

 

Agustin

 


Ed GRAFTON (Houston, Texas, USA)

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