Hello all,

Here is a series of IR - CH4 image plates of Jupiter obtained on Jan 8, 10,
25 and Feb 03, 05. All images show the GRS and WOS BA.

CH4 filter - 889nm/5nm
IR filter - 830nm and above

The two images on the left of each plate (UT and filter info included) were
used to produce cylindrical planispheres using PC-JUPOS software, from
which the four images on the right of each plate were originated. These
four images are a CH4 frame, two IR frames and a color composite of IR+CH4.
Two IR frames were included in order to allow an easy assessment of both
latitude and longitude co-localization of the CH4 image of BA with its IR
counterpart.

I must stress that no attempt was made to "tune-up" the alignment of the IR
and CH4 planispheres with respect to each other after they were originated,
namely using the GRS or anything else as a reference point. What was done,
for each IR-CH4 image pair, was simply to enter the IR image in PC-JUPOS
software, typing the date and UT, asking the software to find an ellipse
profile for the planetary disk and producing the first planisphere. Then
the CH4 image was uploaded to PC-JUPOS and the respective date and UT was
entered. The same ellipse profile originated  for the IR was used for the
CH4 image (its is virtually impossible to originate a good profile for this
type of image due to strong limb darkening). What was done manually was to
fit the profile into the CH4 image without knowing what kind of putative
co-localizadion might occur. The CH4 plansiphere was then originated.

A RGB planisphere image file was originated using the CH4 image for the R
channel and the IR image for the G and B channels. The false color
planisphere thus originated showed a very good co-localization of the IR
and CH4 images of both the GRS and WOS-BA. Notice that only a small portion
of the cilyndrical projection, specifically showing the GRS and BA, is shown.

In all the images so far analysed this way (starting on Jan08 until
yesterday Feb 05), the CH4 image of BA is smaller but rather well centered
onto the IR counterpart aspect of this WOS. In practically all IR images a
(smaller) central substructure, is seen in the IR images of BA.

I wonder that the above morphology may suggest that BA still presents an
"oval within a larger oval" appearance that was captured by HST and Cassini
some time ago, and if the CH4 oval (centered in the IR conterpart of the
WOS) may simply represent the "inner oval".

Apparently no changes in this morphology have so far been noticed during
the GRS-BA approach, and I also wonder which, if any, changes are most
likely to occur... A disruption of the IR outer rim with preservation of
the methane-bright structure? A distortion of the CH4 image with respect to
the IR image?

Your thoughts?

Best wishes

Antonio

ALPO-Japan Latest　Jupiter Section