New photometric data for the red giants in the open cluster NGC 5822: membership, chemical composition and physical properties

New photoelectric UBV, DDO, and CMT1T2 data of 14 G and K stars in the field of the open cluster NGC 5822 are presented. By applying two independent photometric criteria 11 stars are found to have a high probability of being cluster giants, while the three remaining stars are almost certainly red field objects. A reddening E(B-V)=0.15+-0.01, a distance modulus of V0-Msub(v)=8.77+-0.18, and an age of about 6-8x108 yr have been derived. NGC 5822 has a mean ultraviolet excess of delta(U-B)=0.00+-0.01, with respect to the field K giants, and a mean cyanogen anomaly of deltaCN=+0.031+-0.008, both implying a nearly solar iron abundance. (author)