NGC 6846

Fundamental parameters of six neglected old open clusters In this paper, we present the first BV I CCD photometry of sixoverlooked old open clusters (Berkeley 44, NGC 6827, Berkeley 52,Berkeley 56, Skiff 1 and Berkeley 5) and derive estimates of theirfundamental parameters by using isochrones from the Padova library. Wefound that all the clusters are older than the Hyades, with ages rangingfrom 0.8Gyr (NGC 6827 and Berkeley 5) to 4.0Gyr (Berkeley 56). Thelatter is one of the old open clusters with the largest heliocentricdistance.In the field of Skiff 1, we recognize a faint blue main sequenceidentical to the one found in the background of open clusters in thesecond and third Galactic quadrant, and routinely attributed to theCanis Major accretion event. We use the synthetic colour-magnitudediagram method and a Galactic model to show that this population can beeasily interpreted as a thick disc and halo population towards Skiff 1.We finally revise the age distribution of the old open clusters, showingthat the previously suggested peak at 5Gyr looses importance asadditional old clusters are discovered.
Photographs of nebulae with the 60-inch reflector, 1917-1919. Not Available
Not Available Not Available

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