Like DEEP2, the DEEP3 spectroscopic targets were primarily selected from the BRI optical catalogs of Coil et al. (2004), reaching a limiting magnitude of RAB = 24.1. However, sources were also targeted based on detections at other wavelengths (e.g. x-ray or far-IR sources), including a sample of optically-fainter sources (R > 24.1) drawn from CFHTLS imaging. A list of the various multi-wavelength sources observed and how to identify those objects in the DEEP3 redshift catalog can be found here.
DEEP3 utilized the DEIMOS multi-object spectrograph on the Keck II 10-m telescope. A total of 56 slitmasks were observed from 2009 – 2011, covering the central portion of the EGS. The orientation of the survey area relative to the CANDELS and 3D-HST programs is given in this sky-coverage map:
In contrast to DEEP2, which employed the 1200 line/mm grating in DEIMOS, the DEEP3 spectra are of lower resolution (R ~ 2500, using the 600 line/mm grating), though covering a broader wavelength range 4550Å – 9900Å (a central wavelength of 7200Å). The GG455 order-blocking filter was used to limit flux blueward of 4550Å, and each slitmask was observed for approximately one hour, depending on the observing conditions (i.e. transparency and/or seeing). Typical slitlengths are ~4-8”, with a standard 1” slitwidth.
The DEIMOS data were reduced using the DEEP2 DEIMOS spec2d pipeline, yielding sky-subtracted 1-d and 2-d spectra for each object. Redshifts were then measured using the DEEP2 Redshift Pipeline, with each redshift inspected by eye and assigned a quality code. For more details regarding the determination of redshifts, refer to the description of the redshift catalog.