| SEB aspect in CH4 after a SEB revival by Christophe.P |
It seems that is has happened already at least twice after a SEB revival ; and it comes along with two other aspects in other filter bands :
- In near IR (or R) the SEB is blank where it is "not dark" in CH4
- In B/UV it is "normally" dark.
This set of images present some old HST images taken after the revivals of 1990 and 1993 (sorry the file is big)
In 1991 the CH4 SEB is less dark than it was in 1993 while faded (Pic du Midi data not included). The belt is blank f. the GRS in IR and very dark in UV.
In 1994 this is the same, with a new feature that we see also in 2011 : the southern half of the Equatorial zone is abnormally dark ("normal" state is very bright). In 2011 both are almost impossible to differenciate. Nothing irregular seems to show up in all other bands...
After a SEB revival, it has been noticed sometimes an "orange flush" over the SEB (John Roger's work). Well visible in 1991, and to my eyes in 1994 the SEB was pinkinsh-orange as well. If the belt is dark in UV and clear in IR, then it must take on a pink-orange hue in RGB.
Therefore the "not dark" state of the SEB could be related to the pink-orange color that would then be a mid-level haze spreading over the relevant longitudes ?
Final remarks :
- 2008 is a counter-example (possibly coherent) : the SEB has a normal dark aspect in CH4 after the revival of 2007, and is active in near-IR. No coloration is noted (BAA report)
- I hardly see the coloration in 2011, except maybe in some small sectors of the belt. Don's RGB included on the set is one of those images ; it also shows small reddish points (barges I assume) in the belt also visible in 1991 and 1994.
- Visual observers should make some estimations of the color of the belt, especially following the GRS, this would be most welcomed...
What do you think ? Christophe
[Christophe Pellier Bruz City,France]
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