Sh2-203 is an HII region in Perseus. It is VERY dim.

Scope:Planewave 12.5" CDK
Camera: Apogee U16M (16803 ccd) w Gen II Astrodon filters
Exposures: 11/8/8 x 10 min RGB, 58 x 20min H-Alpha

Paramount ME guided w an Astrodon MMOAG and SBIG ST402ME

Image acquisition with TSX and CCD-Commander

Calibration and processing all in PixInsight: GradientCorrection, SPCC, BlurX, NoiseX, then Seti Astro's Statistical Stretch followed with some Curves, HT.
H-Alpha: Gradient Correction, BlurX, NoiseX, StarX then Seti Astro's Statistical Stretch then curves on the starless version.
Starless Ha combined with the RGB via HaRGB_Combine in PixInsight. Save-as-TIFF