Ou4 Nebula

This photo is composed of two narrow band channels, that is Ha channel and OIII channel, with red representing Ha and blue and green consisting of OIII channel. The blue squid in the photo is mainly from the light of OIII in the Ou4 nebula, which is almost invisible in the Ha channel. However, this blue squid is completely hidden in the red bat of the Ha channel.The total exposure time of this photo is about 45 hours, with Ha channel exposure of about 12 hours and OIII channel exposure of about 33 hours.This photo was taken in May and June 2022 at my remote observatory in Zhangjiakou City, Hebei Province, China. My equipment: SharpStar FRA 600/5.6 APO with 0.72 Reducer, ASI ZWO 6200 MM, Paramount MX mount and Astrodon LRGB and 3nm HSO filter.