M42 processing question

Here is an image of M42 i have been working on. I processed in IRIS and for some reason there is a diagonal cut off line where it seems any brighter data has been clipped. Any ideas? I think this would look pretty good without that line.

-KDG

Attached Image:

Kerry,
This is a nice image - too bad about the diagonal line. I don't think I have ever seen anything like that.

What is your image data source? Is this from a one shot color CAM or is it separate LRGB exposures?

Kerry,

you are right - the image is lovely.
concering this line...
- how many frames were used?
- perhaps most of them you had your framing off...? does this make sense?

go ahead and tell us a bit more about the scope setup and the frames you used.

I have seen lines like that when trying to align some dim subs in CCDSoft. For some reason the alignment gets totally out of whack on one or two subs. Sometimes I can definitely trace it to a stray hot pixel in the flaky frame, but other times I have no clue as to why it aligns poorly. And I can get things like that when only one or two subs are off (surprisingly few). If you look at the aligned subs individually you might see something. Good luck.

Charlie

The photo was taken with an unmodified Canon 30D through a WO ZS 80ED II. It was my first shot through the 80ED. I had it piggybacked on a C8 and tracking was a GM-8. I did not guide but my polar alignment was spot on. It was kind of windy, so I may have let a bad frame sneak in. This was a stack of seventy thirty second exposures. Sounds like i may have gotten a bad frame in the stack? Also, the setup is a bit on the heavy side, maybe too much for the GM-8, but I had to try the 80ED and this is the only way I have to do that right now.

Thanks for the help and the comments!

-KDG

I discovered the problem! As it turns out, the error was in my method for removing the background gradient. This was discovered when I saw the same issue on an M81/M82 photograph which had very carefully selected frames. From now on I will be removing gradients with software other than IRIS. I will post a reprocessed M42 soon!

Thanks for all the help!

-KDG