J/AJ/110/2844 J/AJ/110/2844 JHK photometry of globular clusters. III. L E Kuchinski J A Frogel Astron. J. 110 2844 1995 1995AJ....110.2844K J/AJ/109/1131 : Paper I: clusters NGC 5927, Terzan 2, NGC 6712, NGC 6838 J/AJ/109/1154 : Paper II: cluster Liller 1. Schechter et al. 1993 PASP 105, 134 Clusters, globular Photometry, infrared We present new JHK photometry for the disk globular clusters NGC 6440 and NGC 6624. These data are initially used to confirm and refine several important results from Kuchinski et al. (1995AJ....109.1131K) for other disk globular. First, we again demonstrate the ability to derive a reddening-independent estimate for the [Fe/H] of a cluster from the slope if its giant branch (GB) in a K, J-K color magnitude diagram (CMD). Second, the reddening corrected J-K color and K magnitude of the center of the horizontal branch (HB) and the J-K color of its red edge are confirmed to be independent of [Fe/H] for these clusters. Thus these parameters can be used to estimate E(J-K) of metal-rich clusters with no knowledge of distance or [Fe/H] and to estimate (m-M) if one can first estimate the reddening. We also confirm that the reddening-independent quantities, the half width of a cluster's horizontal branch (HB), and the color difference between the center of the HB and the GB at the level of the HB, both appear to be insensitive to metallicity. The JHK colors of NGC 6440 are similar to those of Liller 1; in both cases these colors are unlike those seen for other globular clusters, field giants, or bulge giants. We have not been able to identify any other cluster parameter that would help to explain these anomalous colors. We have assembled V photometry from the literature for the clusters in our sample and VK photometry for two additional disk globular clusters from Davidge et al. (1992ApJS...81..251D). We conclude that K, J-K CMDs are preferable to K, V-K CMDs as tools to study basic cluster properties. Finally, we compare our data with theoretical isochrones for metal-rich clusters and present observational evidence that the dependence of the V-K color of the GB on [Fe/H] may be different for halo and disk globular clusters. This difference may be related to differences in the [O/Fe] values for the two cluster systems.

NGC 592715 27.6 -50 39 NGC 662418 23.6 -30 21 NGC 644017 48.9 -20 22 NGC 671218 53.0 -08 43 M 71NGC 683819 53.7 +18 47

ID Identification number --- Xpos X coordinate (from East to West) number=1 the plate scale is 0.35"/pix. pix Ypos Y coordinate (from South to North) number=1 the plate scale is 0.35"/pix. pix Kmag K magnitude mag J-K J-K color index mag H-K H-K color index mag V-K V-K color index mag Code Exposure code number=2 3 = 3s exposure, 10 = 10s exposure, 20 = 20s exposure 203 = color data from both sets (3s and 20s) (table3 only) --- Note Notes number=3 NO = star with DoPhot error >=0.06mag (DoPhot, Schechter et al. 1993) --- ID Identification number --- Kmag K Magnitude mag V-K V-K color index mag Patricia Bauer CDS 1996Aug09Leslie E. Kuchinski <lek@payne.mps.ohio-state.edu> J_AJ_110_2844.xml