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Messier 77 is a barred spiral galaxy located 62 million light-years away in the constellation of Cetus. Also known as NGC 1068, LEDA 10266 and Cetus A, it has an apparent magnitude of 9.6.
Messier 77 was discovered by the French astronomer Pierre Méchain in 1780, who originally identified it as a nebula. Méchain then communicated the discovery to his colleague, the French astronomer Charles Messier. Messier believed that the highly luminous object he saw was a cluster of stars, but as technology progressed its true status as a galaxy was realized.
At 100,000 light-years across, Messier 77 is one of largest galaxies in the Messier catalogue — so massive that its gravity causes other nearby galaxies to twist and become warped. It is also one of the closest galaxies with an active galactic nucleus (AGN). Such active galaxies are among the brightest objects in the Universe and emit light at most, if not all, wavelengths, from gamma rays and X-rays all the way to microwaves and radiowaves.
Despite its status as a popular target for astronomers, however, Messier 77's accretion disk is obscured by thick clouds of dust and gas. A few light-years in diameter, the outer accretion disk is dotted by hundreds of distinct water maser sources that hinted for decades at deeper structures. Masers are distinct beacons of electromagnetic radiation that shine in microwave or radio wavelengths; in radio astronomy, water masers observed at a frequency of 22 GHz are particularly useful because they can shine through much of the dust and gas that obscures optical wavelengths.
Bucknell University astronomer Jack Gallimore and colleagues set out to observe Messier 77 with twin goals in mind: astrometric mapping of the galaxy's radio continuum and...
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