DEEP3 Galaxy Redshift Survey


Here, we describe the basic parameters of the DEEP3 Keck/DEIMOS spectroscopic observations, including details regarding the target selection and data reduction. Further information will be added to the webpage as time permits.

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 with the ongoing 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.

In the figure, the smaller white points show the distribution of objects in the DEEP2 spectroscopic sample (most of which is included in the DEEP2 Data Release 3). The green points show the DEEP3 survey area, which covers the entirety of the CANDELS and 3D-HST regions.