This narrowband image of the Bubble Nebula is the result of 15+ hours of integration divided roughly equally between SII, Ha, and OIII filters (3-nm bandpass), and spans about 30' to a side, at a plate scale of about 0.47"/pixel. The tone mapping has regions dominated by Ha in orange-red, SII in orange-yellow, and OIII in light blue, with the three channels overlapping strongly in some areas.
About the title, I know that this is a stretch (pun intended!), but I hope that the colour, texture, and framing of this region of the Bubble might bring to mind a couplet from a memorable
rhyming chant by the witches in Shakespeare's Macbeth (Act 4, scene 1): "Double, double toil and trouble / Fire burn, and cauldron bubble". No doubt I owe apologies to Shakespeare for this!
The data was acquired over the course of fifteen nights from November of 2021 through January of 2022. Sky conditions in that period were often poor, and I ended up rejecting an additional 16+ hours of exposures based on seeing and sky-background cuts.
This is actually the third image in a row from 2021 that I've posted only now, having left the data sitting in an SSD drive all this time! I always seem to be acquiring new targets, with not enough time to process all of the data that I've already captured. But the
catastrophic weather in California of the past few months had kept the SRO closed almost continuously, which gave me brain space to catch up on old data. Thankfully, that period seems to have passed, although observatory time is obviously of no consequence relative to the lives impacted by these extreme weather events.
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