Portion of Rosette Nebula (NGC2237)

I decided to disassemble my Canon 350d that I had modified a few years ago. I have never been happy with the amount of dust that was on the new filter / sensor since I did the modification. I took everything apart and spent an hour and a half cleaning the filter and sensor. Reassembled and took it out to capture some new flat frames to see if there was any improvement. I am very happy with how clean everything came out. I can no longer see any dust in my flats so it appears I was successful. What this amounts to is now I can post process without having to spend a lot of time 'fixing' the areas that had so much dust.

I decided to try the Rosette Nebula as my 'test' to see how well my cleaning worked. Here's the results.

SkyWatcher 254N telescope
Orion Atlas EQ6g mount
Canon 350d (modified)
Guided
30 x 2 min images (guided)

from Wikipedia:

The Rosette Nebula (also known as Caldwell 49) is a large, circular H II region located near one end of a giant molecular cloud in the Monoceros region of the Milky Way Galaxy. The open cluster NGC 2244 (Caldwell 50) is closely associated with the nebulosity, the stars of the cluster having been formed from the nebula's matter.
The complex has the following NGC designations:

• NGC 2237 – Part of the nebulous region (Also used to denote whole nebula)
• NGC 2238 – Part of the nebulous region
• NGC 2239 – Part of the nebulous region (Discovered by John Herschel)
• NGC 2244 – The open cluster within the nebula (Discovered by John Flamsteed in 1690)
• NGC 2246 – Part of the nebulous region

The cluster and nebula lie at a distance of some 5,000 light-years from Earth ^[3]) and measure roughly 50 light years in diameter. The radiation from the young stars excites the atoms in the nebula, causing them to emit radiation themselves producing the emission nebula we see. The mass of the nebula is estimated to be around 10,000 solar masses.
A survey of the nebula with the Chandra X-ray Observatory has revealed the presence of numerous new-born stars inside optical Rosette Nebula and studded within a dense molecular cloud. Altogether, approximately 2500 young stars lie in this star-forming complex, including the massive O-type stars HD 46223 and HD 46150, which are primarily responsible for blowing the ionized bubble.^[4][5] Most of the ongoing star-formation activity is occurring in the dense molecular cloud to the south east of the bubble.^[6]
A diffuse X-ray glow is also seen between the stars in the bubble, which has been attributed to a super-hot plasma with temperatures ranging from 1 to 10 million K.^[7] This is significantly hotter than the 10,000 K plasmas seen in HII regions, and is likely attributed to the shock-heated winds from the massive O-type stars.