  We present an extended analysis of the SCUBA observations of the Hubble Deep
Field (HDF), expanding the areal coverage of the Hughes et al. 1998 study by a
factor of ~1.8 and containing at least three further sources in addition to the
five in that study. We also announce the public release of the reduced data
products. The map is the deepest ever made in the sub-millimetre, obtained in
excellent conditions (median 850um optical depth of 0.16). Two independent
reductions were made, one with SURF and the other with a wholly algorithmic IDL
analysis which we present in detail here. Of the three new sources, all appear
to be at z>~0.9 and one is provisionally associated with an Extremely Red
Object (I-K>5). There appears to be no significant cross-correlation signal
between the 850um fluctuations and sources detected by ISOCAM, the VLA or
Chandra, nor with Very Red Objects (I-K>4), nor quasars and quasar candidates
in the HDF (notwithstanding a small number of individual weak candidate
detections). This is consistent with interpretations where the 850um-selected
galaxies are at higher redshifts than those currently probed by ISOCAM/VLA, and
predominantly not Compton-thin AGN. There are only one or two compelling cases
for the radio source being the sub-mm source. Nevertheless, most SCUBA-HDF
point sources have a nearby radio source apparently well-separated from the
sub-mm centroid.

Astrophysics