1998A&A...331...70G

JK infrared photometry for the bulge globular cluster NGC 6553, combined with high resolution visual VI observations are presented and discussed in connection with the bulge metal rich population. The infrared data were taken with IRAC2 at ESO 2.2m telescope while the optical counterparts are from Hubble Space Telescope (HST). We find a mean magnitude for the horizontal branch of V_HB=16.92, and K_HB=12.42±0.01. Assuming a reddening of E(B-V)=0.7, the mean distance modulus is (m-M)₀=13.6 giving an heliocentric distance of 5.2Kpc. This distance is slightly higher than that previously published by Ortolani et al. (1990A&A...236..362O, hereafter OBB90). The brightest giants have been detected at K∼6.5 and (V-K)=13.10 transforming to M_K=-7.34 and (V-K)₀=11.20, which are exceptionally high values for a globular cluster. The metallicity has been found to be consistent with previous values and an average of [Fe/H]=-0.22±0.05 has been adopted. The helium abundance estimated via the R' method yields Y_p∼0.28±0.03.