Thanks for all your help guys, I think that I may have found a candidate for the problem; me, operator error!
Using CCDStack, after calibrating the raw files with the master Dark and Flat Field Frames, I would normally use the Data Reject procedure of “reject hot/cold pixels”. Although I’m not absolutely sure, when I ran the “hot/cold pixel” procedure to identify them based on the selection criteria, I think (?) that I may have forgotten the next step, to then impute those pixels. As a result, they remained in the frames and so appeared in the final image as the rogue pixels.
As part of my investigation I opened and I blinked the Darks and Flats to make sure there were no rogue frames in the sets and the image data appeared consistent from frame to frame, so I thought the problem would not likely lie here.
I then ran through my workflow and ticked off the procedural steps to make sure that I had followed them accurately. Doing this, the “holes” vanished!
So, once again, thank you for all your advice and suggestions in helping me resolve this problem – I really appreciated your efforts and please accept my apologies for my slack processing.
But, we do have a happy ending. Here is M16 in LRGB using the C9.25 at F6.3 with the ST2000 and CFW10 with a 1st Qtr Moon some 90 degrees away. As Gerald had a set of Ha, OIII and SII filters in the CFW10, I also managed to grab 20mins through each filter although auto guiding wasn’t as accurate in these latter frames as I had gone past the meridian and the mount was “floating” in the gears.
L=12x5min, RGB=1x10 min each.
Ha, OIII and SII 1x20 min each.
Cheers
Dennis
