Sh2-203 is an HII region in Perseus. It is VERY dim hence the 25 hours of H-Alpha to make it pop.

Scope: AP155EDF w 4" FF and FocusBoss II
Camera: Moravian Instruments G4 (16803 ccd) w Gen II Astrodon filters
Exposures: 14/14/13 x 10 min RGB, 75 x 20min H-Alpha or 32+ hours total

Paramount MX guided w a 60mm Achromat 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

Photoshop cleanup, crop and rotate to put North UP and Save-for-Web

Click on the image to see them fill the screen

Oct 2025
Lucknow, Ontario