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In fact the filter you are using covers all the methane rays, 619nm, 750nm+/- and above.
Can you think possible to perform on the 619nm only or the 750nm only (the filter needs to be found)?
Stanislas
Hi,
Yes indeed, the next uranus opposition will be also interresting.
The planet axis will be more turned to earth sothat the geographic pôle will be fully accessible.
Regarding your attached picture, what is remarquable is the absence of a dark geographic pôle. I suppose you had used a deep red filter, may be the 685, sothat this may be the reason why.
However, we can point out the fact that some observers showed a dark pôle or a ring using a 610 and 685 filter.
So could be controversial?
Personnally, the dark pôle was collected but visually. Here an example of drawing performed with a 305mm (was done also through 150-203mm). This is not the same color segment of observation in fact.
As a comment considering the methane rays in uranus atmosphere, mainly, the 619nm orange red, the 750nm around NIR and above, can you consider possible usually the performance of observations using bandpass filters only eg, the tricolor R that covers the 619nm ray, the 685 for the 750nm band and the 742 for above with camera cutting at 1000nm around?
A question for matter of reading the atmosphere of the planet at different depthes.
Your comments about are welcome.
Stanislas
Hi Richard,
Thanks a lot for the present input you brought here and the fact that Something had been collected visually and by Imaging in visual bands few years ago. This is an information for me. We were always on a controversial subject among the community.
Now, if the AL observation must be undertaken Under night conditions, with evidence this will avoid further discussions. Easy to understand.
However, we could do some analogy with the moon AL, bright Under a night sky. For the anecdote, recently on May the 21st, on daylight, on a transparent sky, the observation of the moon (1st quarter) with the naked eyes allows me to capture the main mare on the mare on the lighted side and some glow on the dark side. Not on the full portion but partially from the Terminator.
Indeed after the sun set time the dark side appears visually clearly also. Surely not the same mechanism of light creation than venus, but this mean some analogy regarding the light levels.
I suggest when somebody see such AL on Venus to practice an exercise consisting in occulting the lighted Crescent in order to fully occult it. The occulter can hide half the eyepiece FOV, so a free portion and the second fully occulted (a TP 2415 kodak film of density >5 located at the focus plan of the eyepice). A second observer can locate the planet behind the occulter, the first observer not knowing this and then try to find the AL not hidden. If well collected then move the scope in order to correlate with the lighted Crescent to see the direct correspondance. This is for avoiding the idea of brain construction of the AL by the lighted Crescent presence. I did personnally with succes.
All these manipulations and arguments donot conduct to built some mechanism of AL creation, but just hypothesis.
I am waiting your publication about the AL occurrences with interest.
Faithfully.
Stanislas
