The planned APOGEE-2 survey area is shown overlaid on a projection of the Milky Way Galaxy — the Milky Way’s disk is a bright horizontal stripe through the middle of the figure, and the Galaxy’s bulge is the brightest portion at the center. Every small dot on this map represents a position that APOGEE-2 will survey.




The APO Galaxy Evolution Experiment North and South (also known as APOGEE-2) will explore the formation history of the Milky Way using the “archeological” record provided by hundreds of thousands of its individual stars. The details concerning how smaller galaxies assembled so that the Galaxy grew from its progenitors are preserved in the patterns seen today in the motions of stars and the abundances of chemical elements that they contain. We will map these patterns using observations from the Apache Point site in New Mexico, and from the 2.5-meter du Pont Telescope at Las Campanas Observatory in Chile, obtaining a complete view of our Galaxy’s history. We are also collaborating with NASA’s planet-finding mission, Kepler, to measure the abundances of carbon, oxygen, nitrogen and iron in planet-hosting stars, to study the role that these elements play in the formation of terrestrial planets.

Key Science Questions

  • What is the history of star-formation and chemical enrichment of the Milky Way?
  • What are the dynamics of the disk, bulge and halo of the Milky Way?
  • What is the age distribution of stars in the Milky Way?
  • Are certain properties of stars associated with whether or not they have planets?

To answer these questions, we rely on stellar spectra taken at near-infrared wavelengths in order to gain a comprehensive view of (1) what are the abundances of elements in stars across our Galaxy, and (2) how stars in various locations are moving through space. These goals raise a number of questions. A good understanding of the science questions rely on other, preliminary questions being answered first.

APOGEE-2 Technical Details

  • Bright-time observations at APO and LCO
  • Fall 2014 – Fall 2020
  • 300 fibers per 7 deg² plate (APO), 3.5 deg² plate (LCO)
  • Wavelength: 1.51-1.70 μm, resolution R~22,500
  • 300,000 stars with signal-to-noise S/N > 100
  • Radial velocity precision ~ 100 m/s
  • Abundance precision of 0.1 dex for 15 elements


  • Principal Investigator: Steve Majewski (UVa)
  • Survey Scientist: Jon Holtzman (NMSU)
  • Project Manager: Fred Hearty (Penn State University)
  • Deputy Project Manager: Jennifer Sobeck (UVa)
  • Instrument Scientist: John Wilson (UVa)
  • LCO Operations Manager: Alexandre Roman (Universidad de la Serena)
  • Pipeline Coordinator: Matt Shetrone (McDonald Observatory)
  • Northern Survey Operations Scientist: Nathan DeLee (Vanderbilt University)
  • Southern Survey Operations Scientist: Ricardo Munoz (Universidad de Chile)