DeepSkyStacker - solution for fewer than 8 stars

[happylimpet]

Hi folks,

I know Im not the only person who's tried in vain to stack images where there are fewer than 8 stars but I could find no solutions online.  So Ive written a programme in BBC BASIC (child of the 80s and its free to download for the PC) which will take the .info.txt files output from the first pass through DSS and add some artificial stars interpolated between any 2 real stars in the image. You run this programme, copy the new .info.txt files back over the originals, and Bob's your uncle.

So in theory you only need 2 stars now. I would expect the alignment wont be so good of course, but it does the job.

Message me if you're interested.

Attached is 8 mins of 2 sec exposures on M91. Not a great image but it made a good test - all the alignment is based on just two stars on the to right hand side.

Cheers

Nick

[NickK]

Have you tried implementing a drizzle?

You'll need to:

* interpolate between pixel values for coordinate fractions (i.e. 0.1-0.9)

* Find the centre point using the interpolated values - try centroid technique

* scale up the output to 2 or 4 times.

* sample each value for the output pixel given the interpolation

* stack the output using a addition or average..

[uhb1966]

BBC BASIC?! OMG ...But hey, if it works! I just had a flashback to 1982!!! :-)

[NickK]

It's funny that BBC BASIC is interpreted.. effectively a crude virtual machine language before it's time.. now C#, Java, and the like think they started it all..

[Chris]

When you load images into DSS you can select stars manually to increase the number of stars for stacking.

Firstly use the slider top right to bring out enough signal in one of your subs. You will see some icons on the right of the image, I think its the one shaped like a star you want? Click on this icon then hover over the stars in the image, a circle should appear around the stars, and it gives you the option of selecting the star if it isn't already. I usually manage to bump my star count from about 5-6 to at least 10-12

You might have to skip the register stage and proceed straight to stacking, this is what I've found. It works though, I've managed to stack 30 second subs in narrowband using this method, well for what its worth  

[happylimpet]

No, this is for cases where there really aren't any more stars!

[Soundologist]

I messaged happylimpet already but I noticed it's been more than a month since he's been on so if anyone here got the software from him I am in serious need lmao.