Seeing Scale (Pickering/Antoniadi)

PICKERING SCALE (1-10): 1-2 = Severe turbulence, image unusable. 3-4 = Poor, large distortions, stack only 5-10%. 5-6 = Moderate, usable for planets, stack 15-25%. 7-8 = Good, fine detail visible, stack 30-50%. 9-10 = Excellent, diffraction-limited possible, stack 50%+. DAMIAN PEACH SIMPLIFIED SCALE: 1 = Terrible. 2 = Poor. 3 = Average. 4 = Good. 5 = Excellent (rare). STACKING GUIDELINES BY SEEING: Pickering 4-5 → stack 5-15%. Pickering 6 → stack 20-30%. Pickering 7 → stack 35-45%. Pickering 8+ → stack 50%+. Most amateur nights are Pickering 5-6; Pickering 8+ occurs only a few nights per year at most locations.