GAL 043.164-00.031 , the SIMBAD biblio

We search the λ = 1.1 mm Bolocam Galactic Plane Survey for clumps containing sufficient mass to form ∼10⁴ M_☉ star clusters. Eighteen candidate massive proto-clusters are identified in the first Galactic quadrant outside of the central kiloparsec. This sample is complete to clumps with mass M_clump> 10⁴ M_☉ and radius r ≲ 2.5 pc. The overall Galactic massive cluster formation rate is CFR(M_cluster> 10⁴) ≲ 5 M/yr, which is in agreement with the rates inferred from Galactic open clusters and M31 massive clusters. We find that all massive proto-clusters in the first quadrant are actively forming massive stars and place an upper limit of τ_starless< 0.5 Myr on the lifetime of the starless phase of massive cluster formation. If massive clusters go through a starless phase with all of their mass in a single clump, the lifetime of this phase is very short.