4 replies to this topic

[HMS_Endeavour]

I have collected a few hours of a DSO which I am getting happy with. However, because I was using NB filters I am not happy with the star colours, so I wanted to go grab a night's worth of RGB just to get some 'real' colour stars to replace the ones I have already grabbed

 

But, in between the NB and RGB sessions. I had to re-assemble my optical train. Obviously when I put everything all back together again, I didnt get my scope/camera rotated as it was before. So now my images are going to be rotated.

 

This isnt a huge issue if i can extract the stars from my nb and just plonk down the new ones, even if they are in the 'wrong place' slightly.

 

My question is this:

If I want to go back and collect more NB data, I am going to have to match the rotation a bit better. Is there a good way to do this? I know NINA can do a quick plate solve and tell me what my current rotation of the camera is - is there also a way to compare this to previous subs and work out what I need to do?

[fmendes]

Yes, you can also load your image (use the file camera, under equipment, then load your previous image), then plate solve and find the camera rotation.

 

Hint, even if you do not have a rotator, connect the manual rotator in NINA, so when you plate solve it will automatically register the rotation as well.

[pyrasanth]

This is not too difficult to achieve but to save heavy cropping this is what you will need to do.

 

Plate solve one of your existing images so you know the camera rotation. This will be found in the astrometric solution.

 

For your new session take a photograph & plate solve it. This will tell you the current position of the camera. You then need to rotate the camera and take images with the camera slowly being rotated to get a match between your first session & your new session images.

 

This is easier if you have an electronic rotator but it is possible to do this manually if the camera can be rotated. The key to this is being able to easily rotate the camera and of course learning to plate solve which has a dependency of you knowing your optics image scale which is given by the formula (camera pixel size/focal length) x 206.3

 

I have done this with my RASA rotating the RASA camera to match the camera rotation on my refractor. The RASA is manual & the refractor electronic for rotation.

[Brain&Force]

I've been doing successful reshoots without even using the manual rotator in NINA or a marked rotator on my OTA (I rotate my whole focuser). NINA's plate solve function tells me the rotation regardless, and it's easier than you think to get within 0.5 degrees of your previous rotation.

 

It does help if you have your RA, Dec, and desired orientation saved using NINA's framing assistant or from a plate solve of your previous stack.

[Stickfarm8]

Like the some of the others that have responded, I use NINA, using the manual rotator option and it has worked very well for me. I was able to merge all of the NB images I had taken with Ha-OIII and SII-OIII filters, on different nights. I still had to use the AlignByCoordinates script on the two master lights after WBPP, and when I followed that with DBextract, the two sets of OIII data aligned perfectly. The manual rotator and manual filter wheel features in NINA are really sweet!

 

Rich