JHKL Photometry and the K-Band Luminosity Function at the Galactic Center

J, H, K, and L photometry for the star's in the central ∼2' (∼ 5 pc) of the Galaxy are presented. Using the observed J - H, H - K, and K - L colors and assumed intrinsic colors, we determine the interstellar extinction at 2.2 μm (AK) for approximately 1100 individual stars. The mean AK(=3.3 mag) is similar to previous results, but we find that the reddening is highly variable, and some stars are likely to be seen through AK > 6 mag. The dereddened K-band luminosity function points to a significantly brighter component to the stellar population (>1.5 mag at K) than found in the stellar population in Baade's window, confirming previous work done at lower spatial resolution. The observed flux of all Galactic center stars with estimated K₀ (dereddened magnitude) ≤7.0 mag is ∼25% of the total in the 2' x 2' field. Our observations confirm the recent finding that several bright M stars in the Galactic center are variable. Our photometry also establishes the near-infrared variability of the M1-2 supergiant, IRS 7.