What happened to my image?

[Larry 1969]

Good day all!

I was able to get out the other night and capture some photons but something along the way went wrong and I don't know where to start...

I synced my mount to the east and right there was M13. I've imaged it before but I really like it so I captured 5 X 3 min subs when I realized my main target (M104) was 50 min from the meridian so I figured this would be a good time to shoot dark and bias frames. That went smoothly...

On to M104... I set the imaging plan up and fell asleep. I awoke to find my subs looking very washed out... It was low in my southern sky and actually passed through some trees and the city of Pittsburgh creates a horrible sky glow so I ended that plan and went outside to see what was going on... The sky was still very clear so I found The West Veil had just cleared the trees in the east and ,boy was I excited! That's probably my favorite target!!! I was able to get 1:30 on it before the clouds rolled in and shut me down for the evening...

The next morning I shot my flats and began processing...

I wasn't going to bother processing 15 min of data on M13 but I'm glad I did! It was probably my best image of the night!

Next, I processed M104 and I found reducing the sky glow very difficult... I wasn't thrilled with the result...

Now for The Veil! The last time I was able to image this it was with my dob so I was super excited to see what my current set up could do with it!

BUT... Something went terribly wrong... You can see just left of center appears smudged out... I didn't touch anything on the scope between images... Any ideas as to what could cause this? Super disappointing for sure...

Thanks for looking!

Larry

[Larry 1969]

OK... I was prompted to go back and review my light frames and they are all pretty good (at least for me) but the image output by DSS id terrible with the same deformation just left of center. The stars in the bad portion are oblong as well...

I re-stacked several times and the output is the same. I even re-registered previously registered frames and jacked the star detection threshold up to 59% so it would only detect 280 stars and the result is always the same...

Here is a single sub that I re-sized and converted to .png but did nothing else to.

Please help!

Thanks!

Larry

[JayTee]

Could it have been a spot of dew that only rears its ugly when you stack all the images? As a suggestion, do two different runs with the veil images. Divide your images in half by the clock time they were taken. So run the earlier half as a separate run, then run the later half as a separate run and compare the two. If they look the same then we need to do more troubleshooting.

JT

[Larry 1969]

Thanks JayTee!
We got it sorted out. It appears that, since there are so many stars it was necessary to check the "Reduce noise by using a median filter" checkbox.
Super weird that it only affected a portion of the image... I still can't wrap my mind around that... Anyway, here's the result.

[JayTee]

That's actually a handy tip. I'll remember that one!

Thanks,
JT

[STEVE333]

Congratulations Larry on finding the source of your problem and then figuring out how to solve it. Don't you love it when things turn out for the best?!

Very nice image you produced too. You have a nice soft touch on the Veil portion. Well done.

Steve

[Larry 1969]

Thanks Steve!
I just unboxed my new camera and I'm really excited to spend much more time on this target!

Larry