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Uranus 2/09/2014 (Some banding present)


FarSide

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Some very stable seeing for me last night gave me an opportunity to experiment with Uranus. I took three runs and only this particularly image yielded any hint detail on the disc. Brightening of the polar north really quite obvious which is almost washed out completely with the 200x example. Not embarrassed to say that Uranus is a very challenging beast to image.

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Hi Nice image. There is clearly banding there, good job.

What size scope are you using ? and do you know what Percent histogram you was getting, and roughly at what focal length ?

I have a cheap Wratten 25 Filter. That might show some banding under reasonable seeing and good trans.

I am thinking of using my 300p as that has the most light grasp. But getting a good histogram with a red filter, even getting good focus. And actually getting the planet on the chip, certainly isn't easy, if it isn't something that's been regularly done.Which for me it is not. Though I have imaged it before many years ago.

I have a go to mount. So that will be easy. I may have to find the focal point on the focuser before I start, Set that, so when the planet is put on the chip, it can actually be seen. If the focus is grossly out, the light spread out will be difficult to impossible, to see the planet using a 3x Barlow and deep red filter. More deep sky than planetary.

Cheers for any info, it may help any attempts I may make. Its been a while since I wanted to image Uranus again.

Once again great shot

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Hi Nice image. There is clearly banding there, good job. What size scope are you using ? and do you know what Percent histogram you was getting, and roughly at what focal length ? I have a cheap Wratten 25 Filter. That might show some banding under reasonable seeing and good trans. I am thinking of using my 300p as that has the most light grasp. But getting a good histogram with a red filter, even getting good focus. And actually getting the planet on the chip, certainly isn't easy, if it isn't something that's been regularly done.Which for me it is not. Though I have imaged it before many years ago. I have a go to mount. So that will be easy. I may have to find the focal point on the focuser before I start, Set that, so when the planet is put on the chip, it can actually be seen. If the focus is grossly out, the light spread out will be difficult to impossible, to see the planet using a 3x Barlow and deep red filter. More deep sky than planetary. Cheers for any info, it may help any attempts I may make. Its been a while since I wanted to image Uranus again. Once again great shot

Okay so - firstly i use a C11 which is a 280mm aperture telescope (11 inches) using (with Uranus) a 2.5X Televu powermate at F/20. In terms of filter: i am not familiar with Wratten so i cannot speculate on them but the classical thought on this is anything under 300mm a 610nm Longpass filter and anything over 300mm a 685nm Longpass filter is useful however i have had success with both. The 685nm has usually the best success rate. The Baader IR 685 has been the most successful because it combines both a very good contrast effect on belts and the best possible light transmission for near infrared. 

Focus and getting the disc on the chip is indeed hard but it is doable with a little practice. I usually start with a native focal length, no barlow and a very well aligned finder scope. I get Uranus dead center in both the telescope and the finder scope and then slowly but surely add my imaging train to the telescope bit by bit making sure that Uranus is dead center and also focused as best as possible. As soon as i place my camera into the image train Uranus is usually ether very close to the chip, i then dead center it using the hand set, or on the screen on the chip and then i can switch my filter over from luminescence (the brightest and easiest one to use to find Uranus over to my near IR filter). Remember that having your gain up very high will help as well as a highish exposure to find the disc easier. 

Focus is notoriously hard with Uranus and Neptune and i usually use a nearby star to focus on and then move back to Uranus to fine tune it. I have a much harder time then most because i still use the original C11 focuser!

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Many thanks for the quick response. the focal length tells me a lot. as does the size of your scope. Clearly at 300 mm primary F15 is easily doable infact I may use a slight extension to increase focal length a touch. getting closer to your F20. The filters you mention I may look into, as I have seen them used many times on Uranus, but do not own one. However the deep red filter Imention can apparently be used with some success, though I am concerned a little about transmission of this Filter which I think is 14% hoping it wont be too sever.

Cheers again for your info. it does help. Nice one Farside

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Very nice - at least as good as anything we've achieved! :)

Your smaller (capture scale?) image handles a 2X resize nicely from just a screen-browser magnifying - what sort of resizing did you use for the larger-scaled image...it seems to have lost the contrast somehow..?!?

Imaged Uranus ourselves on Friday last but down in Oz it doesn't quite make 50° at culmination where we are and you need pretty nice seeing at that altitude with this difficult target...even with the C14 we could only manage a "paint-drying" 3fps.

Congratulations once again! :)

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  • 2 weeks later...

Really well done Farside, I had a go at this last year but didn't have a mono cam at the time. I took an hour long video aswell with a C11 and ZWO coloured cam. I couldn't get any detail so I know how difficult this is! I am hoping my C14 turns up very soon so I can have another go while it's at it's closest. I will try this with a ZWO mono cam and a Baader 685 filter. Hopefully the extra light will help somewhat. Just out of interest how did you get it in colour? Surely not an RGB? Top work again! :icon_salut:

Regards

Harvey

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Yes very nice, thanks, was unable to sleep last night, up for a cupper and at 2am was still pleasant in the back garden, surprised to see how good the sky's were in central Oxford, nice to think you were imaging and making good use of them.

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