tkottary is right. But...since you're using a DSLR, and (I assume) saving as a RAW file, it can be a bit more involved.
FITS files saved from dedicated astronomy cameras have the RA/DEC coordinates of the center of the image embedded in the header.
RAW files don't.
So if you load up one of your CR2 RAW files, you'll have to use the blind solver (assuming you've set one up in NINA) and that can take a while or sometimes fail.
Here's what I think is a better way: Go to the Sky Atlas in NINA. Search for the main target object in your images that you've already taken. Once you find it, select it and click (on the right of the target info) "Set for Framing Assistant." That will send the coordinates of the target to the Framing Assistant, and now it has coordinates that are at least in the ballpark of your image.
Once you're in Framing Assistant, NINA will already be trying to load the NASA Sky Survey image of your object -- click on the big "X" button near the top left to make it stop trying to do that.
Change the "Image Source" dropdown selector to "File." Then click on the "Load Image" button just below it (which used to be the big "X" that you already clicked). It will open a file selector dialog box. Find and select your RAW file, then click OK. NINA will load for a bit, then tell you that the image needs to be platesolved, and will use the Framing Assistant coordinates you already set (from the Sky Atlast) as the suggested coordinates, and ask if you want to use those. Click "Yes" (asking if reference coordinates should be taken).
It will then platesolve your image to find the exact center, size, and rotation, fill those into the Framing Assistant fields, then display your image.
Now you can send those exact coordinates to the Sequencer, and use them to do another sequence at exactly the same spot you were before.
I just tried this with an M42 image I took with my DSLR 8 months ago, and it worked fine.
Hope that helps!
Edited by OldManSky, 16 September 2019 - 02:02 PM.