[ozstronomer (Geoff)]

I have been successfully using Nebulosity for a long while but I can't work out what has gone wrong with these frames.

I imaged Ngc1333 in RGB+Ha last night and the night before. Today i've run the usual processing routine with Nebulosity; Darks. Flats and Lights and PS3. After processing I noticed a series of dots through the image that I can't explain.

I've gone back and checked the images straight from the camera (no darks or flats applied). The attached is 3 frames of Ha 10min each and 4 frames of blue 10min each, stacked via Nebulosity.

It appears to be background noise that has not aligned. If I stack 3 images there are 3 dots, 4 frames = 4 dots etc

The frames seem to be miss aligned somehow. The main stars are aligned but the background ones seem to move.

I wondered if the darks I have are not subtracting out the noise which is why is shows up on the final image?

I have included the final image from PS3

Any suggestions appreciated