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Venus at High Phase in Infra Red

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ronpal's picture
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Joined: 22/09/2015 - 22:18
Venus at High Phase in Infra Red

1 The Section  co-ordinator has encouraged members to try and observe Venus in IR and UV out to  as high a phase as is safe. [I disregard UV in tis note.]
I could already sense  that, after nearly two years, my learning curve for imaging Venus had hit a plateau. So, before responding to this challenge, I decided to benchmark my recent results with others using similar equipment; a 14inch [355mm] SCT, a ZWO ASI224MC-S camera [sensitive to IR] and narrow pass filters of 685 nm [Near IR] and 850nm [IR].  I came away very  disappointed!  I therefore appeal for some helpful suggestions.
1]My observatory is located someway North, at latitude 55, so For the past several months Venus has been very low.  The image has thus proven quite poor but-
2 Experience says that , for my site at least, imaging near dawn will be more successful than at say mid-day. Air seems more steady, despite presenting the light with a greater air mass to pass through.
3 Despite an average  dawn altitude of only 20 degrees, early morning imaging this year has only successfully registered features every third session. In recent weeks, this has increased to every other session [altitude has increased to more than 30 degrees].
4 Returning to the Benchmarking  exercise; comparing my captures with those of others, over a similar period, shows that  theirs generally possess very much more contrast than my faint barely visible features.
5I capture at gain levels of around 50%, since a an earlier series of tests shows give the best balanced image. Is this a mistake?
6 By employing fairly brutal post processing, I find I can start to replicate contrast levels commonly portrayed in the wider  Planetary Imaging community. This suggests my initial capture must be  at fault. Any comments?
I would appreciate helpful suggestions  and direction, before Venus achieves conjunction in August

Ron Palgrave