We have imaged a 45 \arcmin \times 45 \arcmin area centered on the Hubble Deep Field ( HDF ) in UBVRI passbands , down to respective limiting magnitudes of approximately 21.5 , 22.5 , 22.2 , 22.2 , { and } 21.2 .
The principal goals of the survey are to identify QSOs and to map structure traced by luminous galaxies and QSO absorption line systems in a wide volume containing the HDF .
The area surveyed is 400 times that of the HDF , and 40 times that of the HDF Flanking Fields .
We have selected QSO candidates from color space , and identified 4 QSOs and 2 narrow emission-line galaxies ( NELGs ) which have not previously been discovered , bringing the total number of known QSOs in the area to 19 .
The bright z = 1.305 QSO only 12′ away from the HDF raises the northern HDF to nearly the same status as the HDF-S , which was selected to be proximate to a bright QSO .
About half of the QSO candidates remain for spectroscopic verification .

Absorption line spectroscopy has been obtained for 3 bright QSOs in the field , using the Keck 10m , ARC 3.5m , and MDM 2.4m telescopes .
Five heavy-element absorption line systems have been identified , 4 of which overlap the well-explored redshift range covered by deep galaxy redshift surveys towards the HDF .
The two absorbers at z = 0.5565 and z = 0.5621 occur at the same redshift as the second most populated redshift peak in the galaxy distribution , but each is more than 7 h ^ { -1 } Mpc ( comoving , \Omega _ { m } = 1 , \Omega _ { \Lambda } = 0 ) away from the HDF line of sight in the transverse dimension .
This supports more indirect evidence that the galaxy redshift peaks are contained within large sheet-like structures which traverse the HDF , and may be precursors to large-scale “ pancake ” structures seen in the present-day galaxy distribution .