PHOTOMETRIC-STUDY OF THE EXTREMELY OLD OPEN CLUSTER BERKELEY 17

Deep BVI CCD photometry is presented for the central part of the poorl y known open cluster Be 17. Relatively shallower VI photometry was obt ained for a larger area covering whole or most of the cluster field. T he cluster is as old as, or possibly slightly older than NGC 6791 (age =9 Gyr). If Be 17 is more metal poor than NGC 6791, its reddening is E (V - I) > 0.7 and its apparent distance modulus is (m - M)v > 15.0. He liocentric distance of Be 17 is estimated to 4.4 kpc. In respect of ri chness the cluster is similar to the well studied old open cluster NGC 188. The CMD of the observed area reveals a relatively narrow main se quence due to disk stars at distance of almost-equal-to 2.2 kpc, i.e., at the location of the Perseus spiral arm.