H-a,O-III,O-III in three versions:
H-a,O-III,He-II:
H-a,He-II,He-II - bluish He-II emission vs the red H-alpha/[N-II] emission:
O-III, Ar-III, He-II channels:
H-alpha/[N-II]: 10 x 300; second: 10 x 300 + 3 x 900;:
Single H-a 300 sec frame (CCD at: 25,5C):
