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NGC 3842
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NGC 3842 (also MCG 3-30-72, UGC 6704 and PGC 36487) is a magnitude +12.8 elliptical galaxy located 290 million light-years away in the constellation Leo.

The galaxy was discovered by German-British astronomer William Herschel using a 47.5 cm (18.7 inch) f/13 speculum reflector at Datchet, Berkshire, on the 26th April 1785.

Right Ascension 11h 44m 02.2s, Declination +19° 56' 59" 

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Title: Two ten-billion-solar-mass black holes at the centres of giant elliptical galaxies
Authors: Nicholas J. McConnell (UC Berkeley), Chung-Pei Ma (UC Berkeley), Karl Gebhardt (UT Austin), Shelley A. Wright (UC Berkeley), Jeremy D. Murphy (UT Austin), Tod R. Lauer, (NOAO), James R. Graham (UC Berkeley and Dunlap Institute for Astronomy and Astrophysics), Douglas O. Richstone (UM Ann Arbor)

Observational work conducted over the last few decades indicates that all massive galaxies have supermassive black holes at their centres. Although the luminosities and brightness fluctuations of quasars in the early Universe suggest that some are powered by black holes with masses greater than 10 billion solar masses, the remnants of these objects have not been found in the nearby Universe. The giant elliptical galaxy Messier 87 hosts the hitherto most massive known black hole, which has a mass of 6.3 billion solar masses. Here we report that NGC 3842, the brightest galaxy in a cluster at a distance from Earth of 98 megaparsecs, has a central black hole with a mass of 9.7 billion solar masses, and that a black hole of comparable or greater mass is present in NGC 4889, the brightest galaxy in the Coma cluster (at a distance of 103 megaparsecs). These two black holes are significantly more massive than predicted by linearly extrapolating the widely-used correlations between black hole mass and the stellar velocity dispersion or bulge luminosity of the host galaxy. Although these correlations remain useful for predicting black hole masses in less massive elliptical galaxies, our measurements suggest that different evolutionary processes influence the growth of the largest galaxies and their black holes.

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