Open clusters or their remnants: $\vec{B}$ and $\vec{V}$ photometry of NGC 1901 and NGC 1252

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Abstract
Photometry in the B and V bands is presented for the southern stellar groups NGC 1901 and NGC 1252. NGC 1901 is often described as an open cluster while NGC 1252 consists of a concentration of about 20 stars centered ≈20′ north of the original New General Catalogue coordinates, and at the southwest edge of the large region previously assigned to this object in the literature. NGC 1901 has a clear main sequence and shares similarities with the Hyades. We derive a reddening value , a distance from the Sun kpc ( kpc) and an age 0.6 ± 0.1 Gyr. NGC 1901 is conclusively a physical system, dynamically comparable to or more evolved than the Hyades. The colour-magnitude diagram of NGC 1252 suggests a turnoff and main sequence, and a total of 12 probable members. We simulated the Galactic field colour-magnitude diagram in the same direction and found it to be a poor match to NGC 1252, suggesting that NGC 1252 is not a field fluctuation. Isochrone fitting to the probable members is consistent with , kpc ( kpc) and an age 3 ± 1 Gyr. NGC 1252 cannot be ruled out as a physical group with the available data. If so, evidence is found that it is not a classical open cluster, but rather an open cluster remnant.
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