I brought my RC8 2 month ago mainly for the purpose of shooting small and dim galaxy, such as M63、M74、M83 in my amateur astro camp where it has a perfect Bortle 2 class sky. The long rainy season in the south-west of China usually ends after October, so I just kept it with me and tested it from my balcony in Guangzhou, where it has a Bortle class 8 to 9 sky.

After shotting with 3nm narrow brand filters for months, took pics of M8 and M20,  I decided to make my attempts to aim at those tiny galaxy and see whether I can make something under such heavy light pollution.

The super typhoon Hinnamnor approached in the last Friday and took most of the clouds away , which offered my a good condition for testing. However, the light polution was still there, the skyscraper (probably 70+ floors tall) stands in front of me never turn its lights off, so I just assume the light polltion will be too heavy to shot NGC253 and didnot expect a good result.

I collected all my Lum data in one night, around 40 frames * 300 seconds. As I expected, the light pollution was so high that the dim light info of NGC253 was nearly submerged by the light pullution and every single LUM frame looks like a FLAT, with huge bright circle in the middle and dozens of dust rings around it. The same thing happened on RGB channels, yet I had no choice but to keep it on.

After collecting data for 4 nights, I deleted a totol of 7hr of data from this 15 hr data set, using the rest of cloud-free 8.3hr data for further process.  The post process was really pain in my ass, the moved dust rings, the reflected light from flattener and focuser, the heavy pollution, all of which made the DBE and denoise like mission impossible.

During the post process, I used StarXTerminator and PS to remove those uncalibrated dust rings and reflected lights as much as possible, the NoiseXTerminator & high contrast Lum mask together for the denoised process.

To my surprise, the final result is quite satisfying.