Abell 4 (PN A66 4, PK 144-15.1, PN G 144.3-15.5) Planetary Nebula in Perseus. Taken Dec. 9, 12, 14
and Dec. 17 2017. Imaged with Starlight Xpress’ SX-825 camera and a Celestron EdgeHD 9.25 at f10,
on a Losmandy G11/Gemini mount. The H alpha and Oiii subframes were 20 minutes binned 1x1, while the
RGB subframes were 5 minutes binned 1x1, resulting in the following total exposures (HA+OIII):(R+Ha):
(G+OIII):(B+OIII) (min) = (320+340):(70+320):(70+340):(70+340). This image is displayed at 0.57
arc-seconds per pixel. Captured with Nebulosity, calibrated, sigma combined in Iris with other
processing using PixInsight LE and Photoshop CS. North is up.