Astrophotography diagnosis of Barnard 144 Panel 3: Light pollution gradient

Favourable conditions for this target. The actual moon context is a waning crescent at 2.9% illumination, 16 degrees above the horizon and 64 degrees from the target: the lunar contribution is negligible, so no moon gradient applies here. The entered Bortle 5 remains the limiting factor, but a 3nm Ha filter rejects most of that pollution, which matches the very low measured background. The residual 57% gradient at 17 degrees therefore points to a local light source or a modest target altitude late in the session. All else equal, shooting closer to the meridian will flatten that ramp.

The setup fits the target well. At 338.9 mm focal length the 1.86 degree field suits a Barnard 144 panel, an extended region best covered as a mosaic: the framing is full and usable. Sampling at 1.765 arcsec/px is comfortable for typical seeing, and the measured 2.3 px FWHM, about 4 arcsec, confirms nothing is lost in resolution. The 3nm Ha is the right pick for Cygnus nebulosity under Bortle 5. On exposure, the 1.88 background-to-black-point margin and 19% dark clipping would flag underexposure in broadband, but at 300s through a narrow filter that is expected and not penalising: 50x300s gives a healthy 4h10 of integration.