The PRIMUS: PRIsm MUlti-object Survey


Redshifts are crucial for studying distant galaxies. They provide an estimate of distance, allowing one to relate observed to intrinsic properties and to cut through the projection on the sky to map the cosmic web and large-scale structure. Wide-field low-redshift surveys such as the SDSS have given us a detailed understanding of the multivariate properties of galaxies, including joint distributions of luminosity, color, morphology, and environment. The question now is how these galaxy properties evolve with time. Deep imaging surveys have covered as much volume at z=1 as the SDSS has at z=0.1, and much of this imaging is panchromatic, with UV and mid-IR data providing critical information about star-formation and stellar mass. For example, the Spitzer SWIRE and GTO surveys and GALEX Deep Imaging Survey have imaged ~60 square degrees to depths appropriate for z=1 galaxies. However, these imaging surveys lack redshifts.


PRIMUS is the largest faint galaxy spectroscopic redshift survey taken to date. It is a spectroscopic survey to z=1 with ~120,000 robust galaxy redshifts covering >9 sq. deg. of the sky, focusing on regions with deep Spitzer, optical, GALEX and X-ray data. Using a custom-built low-resolution prism on the IMACS instrument on the 6.5m Magellan/Baade telescope, we are able to obtain redshifts of faint galaxies ~10x faster than comparable spectroscopic redshift surveys with a precision of dz/(1+z)<0.005. This technique is faster than photometric redshift surveys and provides more precise redshifts.

PRIMUS is done taking data. We have released our redshift catalog and are writing science papers (arXiv Publications). Funding for PRIMUS is provided by NSF (AST-0607701, AST-0908246, AST-0908442, AST-0908354) and NASA (Spitzer-1356708, 08-ADP08-0019, NNX09AC95G).

Any questions regarding PRIMUS or DR1 should be directed to Alexander Mendez (

For any publication making use of PRIMUS data, the following acknowledgment should be included:

Funding for PRIMUS is provided by NSF (AST-0607701, AST-0908246, AST-0908442, AST-0908354) and NASA (Spitzer-1356708, 08-ADP08-0019, NNX09AC95G).

Survey Papers

The two PRIMUS survey papers are given below.

  • The PRIsm MUlti-Object Survey (PRIMUS) I: Survey Overview and Characteristics
    Alison L. Coil, PRIMUS TEAM
    [ApJ, 741, 8 (2011)]
  • The PRIsm MUlti-Object Survey (PRIMUS). II. Data Reduction and Redshift Fitting
    Richard J. Cool, PRIMUS TEAM
    [ApJ, 767, 118C (2013)]

Science Papers

  • PRIMUS: Galaxy Clustering as a Function of Luminosity and Color at 0.2<z<1
    Ramin A. Skibba, PRIMUS TEAM
    [ApJ, 784, 128 (2014)]
  • PRIMUS: Infrared and X-ray AGN Selection Techniques at 0.2<z<1.2
    Alexander J. Mendez, PRIMUS TEAM
    [ApJ, 770, 40M (2013)]
  • PRIMUS: An observationally motivated model to connect the evolution of the AGN and galaxy populations out to z~1
    James Aird, PRIMUS TEAM
    [ApJ, 775, 41A (2013)]
  • PRIMUS: Constraints on Star Formation Quenching and Galaxy Merging, and the Evolution of the Stellar Mass Function From z=0-1
    John Moustakas, PRIMUS TEAM
    [ApJ, 767, 50M (2013)]
  • PRIMUS: The dependence of AGN accretion on host stellar mass and color
    James Aird, PRIMUS TEAM
    [ApJ, 746, 90A (2012)]
  • PRIMUS: Enhanced Specific Star Formation Rates in Close Galaxy Pairs
    Kenneth C. Wong, PRIMUS TEAM
    [ApJ, 728, 119W (2011)]
  • PRIMUS: Obscured Star Formation on the Red Sequence
    Guangtun Zhu, PRIMUS TEAM
    [ApJ, 726, 110Z (2011)]
PRIMUS Coverage Map