Lucky imaging of double stars

[PatG]

Hi All

Recently been getting into some casual observing of double stars, as these make good targets under light polluted skies and I’m thinking about having a go at some lucky imaging. 
 

Anyone practicing this technique? What sort of kit is best suited / are you using? 
 

Great to get some suggestions and some example images. 
 

Pat

[MylesGibson]

Do you mean lucky imaging as in the technique used for planetary imaging? Take a short video and stack individual frames?

I've not tried that..... Would have to be a very bright pair for it to work

[Cosmic Geoff]

I tried this a few times using simlar techniques to planetary imaging. It works well with doubles of roughly equal brightness, less so when the brightnesses of the components are very unequal.

[MylesGibson]

@Cosmic Geoff great effort! Might have a go at this myself sometime then....

[PatG]

Thanks for the feedback people.

Yes I was reading a specification for a ZWO ASI 183 camera which is relatively high resolution with pixel size of circa 2.4µm states .... Fast FPS can be used in solar and lunar imaging, as well as for live viewing/EAA.The high speed readout may also be used for real-time focusing, true lucky imaging of double stars and other small objects, planetary imaging of the major planets in the solar system, and much more

I was looking at this camera potentially for some EAA, combined with a smallish refractor but reading the above, I guess the combination of small pixel size /  high resolution combined with a high FPS lends itself to a similar approach to planetary imaging, i.e. taking short videos and then selecting the best subs to stack to take advantage of changes in seeing / atmospheric conditions.

Interesting technique and in context of double stars & resolving close doubles an interesting prospect with a camera with a relatively small pixel size perhaps?

Great image of the trapezium doubles Geoff, thanks for posting!

Pat

 

 

 

[PatG]

Albireo circa 2013, captured with a Meade Lx90 200mm and a Mallincam Extreme I think

[7170]

@PatG here is the result of lucky imaging that I took at the end of last year as a test but I failed to record the target name correctly.  The only notes I do have is that the separation is sub arc second. 720 subs at 0.010s each (possibly with a blue filter), stacked the best using AutoStakkert (but I didn't note the parameters).

Do a search for double star speckle measurement, or have a watch of this video. Ideal equipment is an SCT and high speed mono camera (using ROI around the double paid). Then use AutoStakkert or Reduc to stack, and Reduc to measure angle and separation. When you do high resolution imaging of doubles you need to measure camera angle and scale using drift calibration (there are some details in the video I linked) and I use SpeckleToolBox too.

It is a great technique, though I will issue a general health warning, you can get obsessed with trying to split very very close pairs by stacking thousands of frames!).

Looking at your website you C11 on G11 using your 41AU02.AS is a great setup to do this type of imaging. The hardest part is often getting the target in the centre of the frame, some people use a separate scope piggybacked as a large finder.

Edited February 22, 2022 by 7170

[7170]

I've just taken the following example of 1 Cam.

An example of a single unprocessed raw sub:

And the best 50% of 1000 frames just stacked:

Stacking 5000 frames as an example would have been better but hopefully the result can be seen from the above. 

 

EDIT: And with 75% of 3800 frames:

Edited February 22, 2022 by 7170

[PatG]

Thanks for your feedback and advice James. I will do some reading up and take a look at the video. The improvement of the images of 1 Cam following stacking is clearly evident. Will definitely be giving this a go and will post some results in due course. Good to know I can give it a try with the imaging source camera too. Thanks for the tips..

Pat