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Jupiter 27th 23:30UT derotated.

Nigella Bryant

By Nigella Bryant
in Imaging - Planetary

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Nigella Bryant

Nigella Bryant

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Hi all, just added this new image from the 27th. This time three images derotated and using registax auto colour balance. Thanks for the tips people, what a great forum to help a beginner in planetary imaging. C11 plus 2.5x powermate and Zwo Asi 462mc. Still some way to go, lol.

 

2023-11-27-2330UTNigellaBryant-1.png

 

2023-11-27-2330UTNigellaBryant-2.png

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Nigella Bryant

Nigella Bryant

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47 minutes ago, IDM said:

That is a lovely image. Seeing for me on the 27th was not that good. I have a C11 but am yet to have success adding a 2x Barlow.

Ian

Thanks Ian, much appreciated. It's been suggested to just image at the native focal length of f10. I don't understand the science behind it but I'm going to experiment on the next clear night. Something to do with oversampling, getting higher frame rates and lower file size. 

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geoflewis

geoflewis

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12 hours ago, Nigella Bryant said:

Still some way to go, lol.

Wow Nigella, what a superb image and a big improvement over your first attempts; the colours in these version are just right. Hence, I have to disagree, you don't 'still have some way to go' - I think you've pretty much already arrived 👏. Now it's just waiting for the best conditions and I'd say small tweaks to your processing, as conditions and data will vary session to session.

I will be interested to see how you get on without the x2.5PM.

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Nigella Bryant

Nigella Bryant

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2 minutes ago, geoflewis said:

Wow Nigella, what a superb image and a big improvement over your first attempts; the colours in these version are just right. Hence, I have to disagree, you don't 'still have some way to go' - I think you've pretty much already arrived 👏. Now it's just waiting for the best conditions and I'd say small tweaks to your processing, as conditions and data will vary session to session.

I will be interested to see how you get on without the x2.5PM.

Thanks Geoff, much appreciated and encouraging. Perhaps I'm to hard on myself, lol. It will be interesting to see imaging at f10 instead of f25. Supposed to be clear tonight and tomorrow. I'll try at both focal lengths as an experiment. 

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geoflewis

geoflewis

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5 minutes ago, Nigella Bryant said:

Thanks Geoff, much appreciated and encouraging. Perhaps I'm to hard on myself, lol. It will be interesting to see imaging at f10 instead of f25. Supposed to be clear tonight and tomorrow. I'll try at both focal lengths as an experiment. 

I suspect that you may be a tad undersampled at f10, but as you say, it will be interesting to see. Do you have anything less than the x2.5 PM that you could try? I think the sweet spot with that camera might be nearer F12/F15 (2.9μm x5 =14.5), but definitely worth trying both with and without the PM. Do you use an ADC, as that would probably give a little amplification by setting the camera further back.

When you loaded the images into WinJupos for derotation measurement, did you note what arcsec/px they were measured at? See bottom right corner in below screenshot for where to get that info...

image.thumb.png.50cc388115ed4b62d9f7517ea9a2b1e5.png

This will allow you to calculate the actual FL and FR of the capture, as it's unlikely to be the nominal F10 of your OTA. (That is if you want to of course 🙂)

Use the below formula to calculate actual FL in mm (C11 nominal is 2800mm).

[Focal Length in mm] = (206.2648 x [Pixel Size in μm]) / [Arcseconds Per Pixel]

(NB ASI462MC has 2.9μm pixels)

....then divide the result by the dia of your OTA (280mm) to get the actual operating focal ratio of the capture.

Hope this helps.

 

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Nigella Bryant

Nigella Bryant

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59 minutes ago, geoflewis said:

I suspect that you may be a tad undersampled at f10, but as you say, it will be interesting to see. Do you have anything less than the x2.5 PM that you could try? I think the sweet spot with that camera might be nearer F12/F15 (2.9μm x5 =14.5), but definitely worth trying both with and without the PM. Do you use an ADC, as that would probably give a little amplification by setting the camera further back.

When you loaded the images into WinJupos for derotation measurement, did you note what arcsec/px they were measured at? See bottom right corner in below screenshot for where to get that info...

image.thumb.png.50cc388115ed4b62d9f7517ea9a2b1e5.png

This will allow you to calculate the actual FL and FR of the capture, as it's unlikely to be the nominal F10 of your OTA. (That is if you want to of course 🙂)

Use the below formula to calculate actual FL in mm (C11 nominal is 2800mm).

[Focal Length in mm] = (206.2648 x [Pixel Size in μm]) / [Arcseconds Per Pixel]

(NB ASI462MC has 2.9μm pixels)

....then divide the result by the dia of your OTA (280mm) to get the actual operating focal ratio of the capture.

Hope this helps.

 

Thanks Geoff, very helpful, I've a 2x barlow but it's for my birthday pressie next week so don't think I'd get away with saying I wanted to test it, lol. I do have an ADC. If I could get to say f15 that would be great I think. I didn't know about Winjupos telling me about the focal length, thanks for that, that will be interesting to know. 

Nigella 

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