Stellar overdensities in the halo: the extent of the Virgo overdensity

We map the three-dimensional extent of the Virgo overdensity by combining distance information from RR Lyrae variables and projected spatial information from the Southern Edgeworth-Kuiper Belt Object Survey and Sloan Digital Sky Survey Data Release 6 photometry. The Virgo overdensity is seen to comprise two filaments 14.degrees 5 x 3 degrees and 10 degrees x 3 degrees, and a circular structure 3 degrees in diameter. Together, the three features span 38 degrees of right ascension and declinations of 2 degrees to - 15 degrees. RR Lyrae variables place the two filamentary features at heliocentric distances of 20 and 17 kpc, respectively, with projected dimensions of 5 x 1 and 3 x 1 kpc.