Jupiter, 06/04/2017

[GuLinux]

As I was shooting the moon (see my previous post in the proper section), I decided to try Jupiter too. I couldn't stay up late (working the next day), so it was still pretty low, I did a quick RGB "just in case".

I think the result is actually much better than expected though:

 

I got much more data from the following days, but I'm still processing them.

 

Shot data and equipment: 

Celestron Nexstar SLT 127 - ASI 178mm - ASI RGB filters

Time: around 23:00 GMT+1

[Mercona]

That is nice. Did you use Barlow lens? I noticed that the telescope is only 1500mm. 

[Annodite]

Very interesting - do you mind sharing me the process and equipment you have to take the image? 

I currently have a 10' Dob Skywatcher with 1200mm and I can't seem to capture an image as good as the one you took, even if I add a x2 Barlow.

 

Thanks!

 

 

[GuLinux]

Hi, Thanks :-) 

the equipment is what I wrote in the previous post (plus a manual  filter wheel for the filters, of course). 

I don't use a barlow: I specifically bought this camera for its small pixels size, 2.4µm.

The resolving power of my telescope is roughly 1 arcsecond. The rule of thumb is that your camera pixels should cover at most a half of that value, to avoid undersampling, and with this camera, and this focal length, I get 0.33 arcseconds per pixel. 

This is a frequent error, one that I have done a lot in the past: if you cover more than a half your telescope resolving power with your camera, it's ok to use a barlow, but if you push that value too much, then you're oversampling a lot, gathering less light, and having much more troubles focusing. 

 

As for the process, it's actually quite simple. I focus with the light filter, or even better the green. Then I try to get the three channels shots as close as possible, to avoid rotation. I use a fixed time for each channel, to further minimise rotation issues (in this shot, one minute per channel). 

I'm using my own application (PlanetaryImager), in the latest release it has presets and histogram statistics , so I carefully measure the histogram for each channel (I keep it under 90%),save camera controls as presets, and then load them quickly after changing filter. 

 

I then stack the frames using autostakkert, i use multiple stacking percentage, usually, and I select the "save sharpened image" checkbox, this way I can use the sharpened version to compare all the percentages, and choose the best stack. 

I then use registax wavelets to enhance  the non sharpened version, combine the channels, I use siril for that, on linux, but even a manual alignment could be fine, and do a few final enhancement in gimp (resampling at 150%, unsharp mask). 

with a bigger focal length (or if it takes too long to change filter) you probably also will want to derotate each channel using winjupos, in my case I didn't see any noticeable difference. 

[Mercona]

That makes sense. I use a Meade 10" that has 2500mm focal but use a canon t5i dslr. My image is much smaller and less detailed. I also have horrible light pollution.

[GuLinux]

well, light pollution in itself is not a big deal. I live in London :-) 

also these images were made during a full moon. planetary imaging is not really affected by foreign light. 

I think your biggest improvement will be to start using a planetary camera, possibly mono, even the cheap ASI 120mm or an equivalent will lead to much better results :-)

[michael.h.f.wilkinson]

Very good shot! Especially with Jupiter so low

[Mercona]

I have a starlight express lodestar x2. Would that be a good planetary camera?

 

[GuLinux]

Mmh.. pixels are a bit too big... Maybe with a good barlow you can work that out, though.. 

I guess it's more of an autoguider than a planetary camera, but I think it might be used successfully, anyway