We present precise optical and near-infrared ground-based photometry of two
Globular Clusters (GCs): Omega Cen and 47 Tuc. These photometric catalogs are
unbiased in the Red Giant Branch (RGB) region close to the tip. We provide new
estimates of the RGB tip (TRGB) magnitudes--m_I(TRGB)=9.84+/-0.05, Omega Cen;
m_I(TRGB)=9.46+/-0.06, 47 Tuc--and use these to determine the relative
distances of the two GCs. We find that distance ratios based on different
calibrations of the TRGB, the RR Lyrae stars and kinematic distances agree with
each other within one sigma. Absolute TRGB and RR Lyrae distance moduli agree
within 0.10--0.15 mag, while absolute kinematic distance moduli are 0.2--0.3
mag smaller. Absolute distances to 47 Tuc based on the
Zero-Age-Horizontal-Branch and on the white dwarf fitting agree within 0.1 mag,
but they are 0.1--0.3 mag smaller than TRGB and RR Lyrae distances.Comment: 5 pages, 4 figures, accepted for publication by ApJ