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More Uranus (28th Oct.) in good seeing..!

Kokatha man

By Kokatha man
in Imaging - Planetary

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Kokatha man

Kokatha man

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...oh no - K-man & partner are at it again...maybe time to see what we can do with Neptune which is riding much, much higher at around 65° in our Southern skies! :wink:

This week we went out to the Murray Mallee and had the luck to find a very good night with reasonable transparency and nice, steady seeing...we got a good collimation on Enif and swung across to Uranus nearby and our only regret was that this was not a night where the storm was transiting the visible face of Uranus... :(

Still, the conditions were good enough to get 4 really nice captures (each 25 minutes or 25,000 frames with the last being a long 50 minute capture for 50,000 frames)

Frame-rate was 18fps and the histogram was set to peak in the low 40% range and gain was at maximum...

There are still 2 of the aforementioned avi's to finalise but here are the third & last - the third (25') delivered over 12,.000 frames at 60% or above quality & the last (50') nearly 26,000 frames at this quality cut-off...giving an idea of the very nice conditions that evening. :)

This time we've "standardised" on a false colour rendering where I've placed a slightly more greenish hue on the WinJupos ephemeris colouration - just an individual choice. :)

I'll post the other images later...

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post-3551-0-81088400-1414801878_thumb.pn

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Kokatha man

Kokatha man

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Thanks James, Pete, Robbie, Mike,  Simmo, Ralph & Mark - appreciated! :)

...we're hoping for a night of really good seeing in the foreseeable future just to see how far we can push the envelope so to speak! ;)

Mike, I think you'd really struggle with the 685nm filter and C11 tbh - this filter lets considerably less light through than the 610nm and even the C14 struggled to pick up even the faintest albedo variation on Uranus with the 685.....of course that was our very first attempt about 6 weeks ago and helped us make the decision to purchase the 610: I've seen some very nice Uranus images with the C11 & 610 filter and Uranus really is more favourably placed for Northern Hemisphere folks! :kiss:  

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Kokatha man

Kokatha man

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Thanks for all the additional compliments fellas - Pat & myself appreciate your kindness! :)

We use a small amount of amplification beyond native f/l scibuff...unfortunately FireCapture seems to calculate silly f/l's for this small disk and is utterly inaccurate but from memory of the settings for the last Saturn images (and I haven't changed my variable amplification unit's setting since then) the f/l is around 5200mm.

I'm only giving my opinion here John, and your's and others' might vary but my belief is that 2 of the regimens used with Uranus imaging are somewhat problematical; ie, using a star as the sole focusing method and "attacking" Uranus processing with wavelets applications...we firmly believe onscreen disk-focusing is both achievable & superior to star-focusing if possible (although star-focusing will certainly get you in the ballpark) and also, because of the subtle albedo variations one resolves on Uranus, wavelets are often too aggressive & noise-inducing.

This is OF COURSE just our perspective...on the subject of seeing we have just returned (like 20 minutes ago!) from a 3ookm trip up North in South Aust. where we experienced better seeing on Monday & Tuesday than anything so far before...this is of course possibly a delusion-inspiring assessment and of course the proof will be in ther processing - so I might have to eat my words on that..!!! :)

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Barv

Barv

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Thanks for all the additional compliments fellas - Pat & myself appreciate your kindness! :)

We use a small amount of amplification beyond native f/l scibuff...unfortunately FireCapture seems to calculate silly f/l's for this small disk and is utterly inaccurate but from memory of the settings for the last Saturn images (and I haven't changed my variable amplification unit's setting since then) the f/l is around 5200mm.

I'm only giving my opinion here John, and your's and others' might vary but my belief is that 2 of the regimens used with Uranus imaging are somewhat problematical; ie, using a star as the sole focusing method and "attacking" Uranus processing with wavelets applications...we firmly believe onscreen disk-focusing is both achievable & superior to star-focusing if possible (although star-focusing will certainly get you in the ballpark) and also, because of the subtle albedo variations one resolves on Uranus, wavelets are often too aggressive & noise-inducing.

This is OF COURSE just our perspective...on the subject of seeing we have just returned (like 20 minutes ago!) from a 3ookm trip up North in South Aust. where we experienced better seeing on Monday & Tuesday than anything so far before...this is of course possibly a delusion-inspiring assessment and of course the proof will be in ther processing - so I might have to eat my words on that..!!! :)

Hi Daryl.

Congratulations on these absolutely superb images.  :smiley:

I have been trying to get some kind of detail on Uranus with my 14" Edge. I too have been using a 610nm filter but am getting nothing. I have tried at F27, which I think is too long with the ZWO 120 mono cam, and also at around F19 (using a 0.7 reducer)- which I really don't like doing with all that extra glass. I was curious what configuration you are using to get a focal length of 5.1 metres? The disc must be tiny! Seeing here in the UK is rarely very good and although I think I have caught a polar cap I can never be sure. I have been focusing using a Bahtinov mask on a nearby star and slewing to Uranus and tweaking focus visually studying the disk on the laptop. I have read conflicting comments on filters, some commenting that the 685nm is the best on the dim outer planets but I agree with you, - if you're not getting anything with a 610nm, it would be more difficult with a 685! I look forward to hearing your views!

Kind regards

Harvey

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Kokatha man

Kokatha man

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Apologies for the delay - thanks Pete & Harvey! :)

Harvey, the albedo variations in the belt "structure" of Uranus can be imaged in various ir wavelength filters (and sometimes even in red) but I think most would agree that the 610 long-pass is the most efficacious...certainly in terms of some sort of "reasonable" frame-rate as the light throughput of the longer wavelength ir filters decreases dramatically with any given aperture.

We focus somewhat similarly to your approach but the seeing needs to be fairly good to start with: I don't recommend "attacking" the raw stack with mild wavelets which is what is generally suggested (my choice of the word "attacking" :) )

Try channel mixing to increase the tonal variation (albedo) which will be in any image taken correctly (focus etc) under good seeing conditions.....we operate the C14 at about f15 (the FireCapture files don't give an accurate appraisal so I cannot say precisely without doing some disk measurements...)

I'll post another image sometime soon from the 9th of this month (November) although you can see it over on CN...in that thread I mention we tried dropping the histogram and upping the frame-rate to about 28fps but there is an "edge rind" artefact that Uranus will throw up during processing (somewhat similar to Mars in appearance) and both the faster fps captures that night (10th) produced this no matter how I processed so I think frame-rates need to stay at a maximum of 21fps or lower for Uranus with the C14...just our findings and others' "mileage may vary!" :)

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