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This slightly different image of the Trifid Nebula was done completely in narrowband using H and O filters. One would expect to not be able to capture the blue reflection part of the nebula (the blue "steam" rising from the top) but apparently this broadband blue nebula is so bright that even with a very narrow (3nm) O-III passband enough light gets through. At the very lower left of the image the bright streak is asteroid (40) Harmonia, which moved through one set of frames taken on 27 June 2017.