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The SDSS-III Apache Point Observatory Galactic Evolution Experiment (APOGEE)is a three year survey that is collecting 100,000 high-resolution spectra inthe near-IR across multiple Galactic populations. To derive stellar parametersand chemical compositions from this massive data set, the APOGEE StellarParameters and Chemical Abundances Pipeline (ASPCAP) has been developed. Here,we describe empirical calibrations of stellar parameters presented in the firstSDSS-III APOGEE data release (DR10). These calibrations were enabled byobservations of 559 stars in 20 globular and open clusters. The clusterobservations were supplemented by observations of stars in NASA's Kepler fieldthat have well determined surface gravities from asteroseismic analysis. Wediscuss the accuracy and precision of the derived stellar parameters,considering especially effective temperature, surface gravity, and metallicity;we also briefly discuss the derived results for the abundances of thealpha-elements, carbon, and nitrogen. Overall, we find that ASPCAP achievesreasonably accurate results for temperature and metallicity, but suffers fromsystematic errors in surface gravity. We derive calibration relations thatbring the raw ASPCAP results into better agreement with independentlydetermined stellar parameters. The internal scatter of ASPCAP parameters withinclusters suggests that, metallicities are measured with a precision better than0.1 dex, effective temperatures better than 150 K, and surface gravities betterthan 0.2 dex. The understanding provided by the clusters and Kepler giants onthe current accuracy and precision will be invaluable for future improvementsof the pipeline.

Calibrations of Atmospheric Parameters Obtained from the First Year of SDSS-III APOGEE Observations