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The Lobster Nebula lies very low in the sky (for Northern Hemisphere observers) in the southern part of Scorpius. At my location, at the best time in the summer, it only gets above the south wall of the observatory for about 75 minutes a night. So this narrowband image was captured over three different nights and consists of just 75 minutes of data for H-alpha, S-II, and O-III.
The small somewhat nondescript open cluster just above the bright blue patch is Pismis 24, and is the cluster responsible for energizing this entire emission nebula.