The Open Cluster Chemical Analysis and Mapping (OCCAM) Survey aims to produce
a comprehensive, uniform, infrared-based dataset for hundreds of open clusters,
and constrain key Galactic dynamical and chemical parameters from this sample.
This first contribution from the OCCAM survey presents analysis of 141 members
stars in 28 open clusters with high-resolution metallicities derived from a
large uniform sample collected as part of the SDSS-III/Apache Point Observatory
Galactic Evolution Experiment (APOGEE). This sample includes the first
high-resolution metallicity measurements for 22 open clusters. With this
largest ever uniformly observed sample of open cluster stars we investigate the
Galactic disk gradients of both [M/H] and [alpha/M]. We find basically no
gradient across this range in [alpha/M], but [M/H] does show a gradient for
R_{GC} < 10 kpc and a significant flattening beyond R_{GC} = 10 kpc. In
particular, whereas fitting a single linear trend yields an [M/H] gradient of
-0.09 +/- 0.03$ dex/kpc --- similar to previously measure gradients inside 13
kpc --- by independently fitting inside and outside 10 kpc separately we find a
significantly steeper gradient near the Sun (7.9 <= R_{GC} <= 10) than
previously found (-0.20 +/- 0.08 dex/kpc) and a nearly flat trend beyond 10 kpc
(-0.02 +/- 0.09 dex/kpc).Comment: 6 pages, 4 figures, ApJ letters, in pres
