Key points are not available for this paper at this time.
In this paper, we present the results of a detailed photometric analysis of Glimpse-C02, one of the most extincted globular clusters of the Milky Way. We built a deep color magnitude diagram spanning ≈10 magnitudes and enabling the very first identification of the main sequence turnoff of the cluster. Due to the extreme reddening conditions of the region where the stellar system is located, a differential reddening correction was necessary. The resulting reddening map shows color excess variations up to δE ( B − V ) ≈ 2.5 mag in the direction of the target. From isochrone-fitting of the differential reddening corrected color-magnitude diagram, we obtained a new estimate of the mean color excess, E(B−V) = 6.33 −0.04 +0.05 , and a distance modulus (m−M) 0 = 14.00 −0.11 +0.26 , corresponding to a distance of d = 6.3 −0.3 +0.8 kpc from the Sun, and a Galactocentric distance of 2.6 −0.7 +0.6 kpc. This distance value, within the associated uncertainties, suggests that the cluster may be located closer to the Galactic Center compared to previous estimates, possibly supporting its classification as a bulge globular cluster. Furthermore, we obtained a photometric metallicity estimate of Fe/H = −0.30 −0.08 +0.10 and the first absolute age determination for Glimpse-C02, resulting in t = 11.9 −0.6 +0.7 Gyr, as typically measured for Galactic globular clusters at this metallicity. We also obtained a new estimate of the center of gravity of the cluster and determined its projected density profile from resolved star counts, finding a high King concentration parameter ( c = 1.97 −0.67 +0.51 ) and a core radius r c = 8.72 −0.35 +0.40 arcsec. Finally, from the surface brightness profile of the system, we derived an integrated H -band magnitude M H = −7.9, corresponding to a mass of M = 3.57 −0.19 +0.22 × 10 4 M ⊙ . Thus, our work classifies Glimpse-C02 as an old and metal-rich globular cluster that is in an advanced stage of its dynamical evolution.
Loriga et al. (Fri,) studied this question.