almcl

Thanks for the thoughts, Olly, Laser jock and Rich. I have had a look at the collimation this morning and it was a little off, but on a previous occasion when the artefact appeared, it was spot on. As for the vanes, I'm not sure. Picture below seems to show the 12 o'clock one slightly bowed and the 9 o'clock one slightly twisted. Would this be enough to cause the problem, I wonder? Or is there something there I haven't noticed? And Olly, you're far too modest, I am pretty certain that massive Dob you showed me the witch's broom and many other exciting things through last September is a Newt and that seemed to be in pretty good order!

Hi, back with yet another question... My last two imaging attempts haven't been crowned with success. Whilst trying to get the Flame and Horsehead nebulas in the same frame, an artefact that isn't on the darks or flats has shown up. Seems to consist of two bright parallel lines. Example below, where its in the upper right part of the image. It almost looks as though it's some sort of reflection from Alnitak's diffraction spikes but on another evening, it showed up in a completely different place. Any thoughts on how to go about finding the source for this would be appreciated. The set up is a Canon 700D attached to a motorised but unguided SW 200P on an EQ5 mount, 20 sec subs, ISO 1600.