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Abell 12 is nicknamed "The Hidden Planetary" because it is located a little under 1 arcminute from the bright magnitude-4.1 star Mu Orionis. Being dim itself (total magnitude about 14), its proximity to Mu Orionis makes it extra difficut to see, especially visually. Photographically it is made easier to capture by using narrowband filters (H-alpha and O-III), which simultaneously increase the contrast in the planetary nebula and decrease the glare of the bright star. With a little extra care in processing it is easy to reveal the hidden gem. Note that the outer red hydrogen shell of Abell 12 is ruptured at the top (north), allowing some of the interior oxygen to spill out.