  We present the discovery of a candidate substellar object in a survey of
young stars in the solar vicinity using the sensitivity and spatial resolution
afforded by the NICMOS coronagraph on the Hubble Space Telescope. The H=12.1
mag object was discovered approximately 2 arcsec from the TW Hydrae Association
member CoD -33 7795 (TWA 5), and the photometry implies a spectral type
M8-M8.5, with a temperature of approximately 2600K. We estimate that the
probability of a chance alignment with a background objectof this nature is < 2
X 10^(-5), and therefore postulate the object (TWA 5B) is physically associated
at a projected separation of 100 AU. Given the likely youth of the primary (~
10 Myr), current brown dwarf cooling models predict a mass of approximately 20
Jupiter masses for TWA 5B.
