The open clusters NGC 2323 and NGC 2539 have been analysed using CCD UBV(RI)KC photometric data, observed at the San Pedro Martir Observatory. Cluster memberships have been determined with ´
the proper motion and parallax measures from the GaiaDR2 astrometric data release. Photometric metal and
heavy element abundances have been obtained as ([M/H], Z) = (−0.10, 0.012) (NGC 2323) and (−0.31, 0.007)
(NGC 2539), from the δ(U–B) technique in the two colour diagrams, which are used to select the appropriate
The estimated reddening of NGC 2323 is E(B-V)=0.23±0.04 using 11 early type stars. For NGC 2539, we find
E(B-V)= 0.02±0.06. For (B–V) colour, distance moduli and distances for NGC 2323 and NGC 2539 are derived as (V0–MV, d (pc)) = (10.00±0.10, 1000±50) and (V0–MV, d (pc)) = (10.00±0.04, 1000±20), respectively.
The median GaiaDR2 distance d=1000±140 pc ($=0.998±0.136 mas) for the likely members of NGC 2323 is
in concordance with its four colour photometric distances 910–1000 pc. For NGC 2539, its GaiaDR2 distance
d=1330±250 pc ($=0.751±0.139 mas) is close to its four colour photometric distances, 1000 pc.
Fitting the PARSEC isochrones to the colour magnitude diagrams (CMDs) gives an old age, 890±110 Myr, for
NGC 2539. Whereas NGC 2323 has an intermediate-age, 200±50 Myr. One Red Clump/Red Giant candidate
(BD-12 2380) in the CMDs of NGC 2539 has been confirmed as a member in terms of the distances dI =950±50
pc and dV=910±90 pc of V I filters within the uncertainties, as compared to the distance, 1000±20 pc of NGC 2539.
This giant’s GaiaDR2 distance (d=1200±70 pc) is not close to these photometric distances.