Let’s say you just imaged some obscure nebula in narrowband under the Full Moon. For our purposes, we’ll work on NGC 7822 using a set of 5-nanometer (nm) Hydrogen-alpha (Hα), 5nm Sulfur-II (SII), and 3nm Oxygen-III (OIII) filters. These three choices constitute what imagers call the Hubble palette because the famous space telescope’s images often use the same filters.
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