  We have identified a new early T dwarf only 3.6pc from the Sun, as a common
proper motion companion (separation 1459AU) to the K5V star Epsilon Indi
(HD209100). As such, Epsilon Indi B is one of the highest proper motion sources
outside the solar system (~4.7 arcsec/yr), part of one of the twenty nearest
stellar systems, and the nearest brown dwarf to the Sun. Optical photometry
obtained from the SuperCOSMOS Sky Survey was combined with approximate infrared
photometry from the 2MASS Quicklook survey data release, yielding colours for
the source typical of early T dwarfs. Follow up infrared spectroscopy using the
ESO NTT and SOFI confirmed its spectral type to be T2.5+/-0.5. With Ks=11.2,
Epsilon Indi B is 1.7 magnitudes brighter than any previously known T dwarf and
4 magnitudes brighter than the typical object in its class, making it highly
amenable to detailed study. Also, as a companion to a bright nearby star, it
has a precisely known distance (3.626pc) and relatively well-known age
(0.8-2Gyr), allowing us to estimate its luminosity as logL/Lsun=-4.67, its
effective temperature as 1260K, and its mass as ~40-60Mjup. Epsilon Indi B
represents an important addition to the census of the Solar neighbourhood and,
equally importantly, a new benchmark object in our understanding of substellar
objects.
