2008MNRAS.384.1733B

We study the nature of the globular cluster (GC) candidates FSR 1603 and FSR1755 selected from the catalogue of Froebrich, Scholz & Raftery. Their properties are investigated with Two-Micron All-Sky Survey field-star decontaminated photometry, which is used to build colour-magnitude diagrams (CMDs) and stellar radial density profiles. FSR1603 has the open cluster Ruprecht 101 as optical counterpart, and we show it to be a massive intermediate-age cluster. Relevant parameters of FSR1603 are the age ~1Gyr, distance from the Sun d_☉~ 2.7kpc, Galactocentric distance R_GC~ 6.4kpc, core radius R_C~ 1.1pc, mass function slope χ ~ 1.8, observed stellar mass (for stars with mass in the range 1.27 ≤ m ≤ 2.03M_☉) M_obs~ 500M_☉ and a total (extrapolated to m = 0.08M_☉) stellar mass M_tot~ 2300M_☉. FSR1755, on the other hand, is not a populous cluster. It may be a sparse young cluster embedded in the HII region Sh2-3, subject to an absorption A_V~ 4.1, located at d_☉~ 1.3kpc. Important field-star contamination, spatially variable heavy dust obscuration, even in K_s, and gas emission characterize its field. A nearly vertical, sparse blue stellar sequence shows up in the CMDs.