Search for new variable stars at the borders of the globular clusters NGC 3201

Abstract

By means of the same method previously used with ω Centauri a search for new variable stars at the borders of the globular cluster NGC 3201 has been made. To this end the author had at disposal 98 blue photographic plates taken with the "Carte du Ciel" astrograph of the La Plata Observatory during the years 1952-61. The size of the plates were; Nº 1-74, 9x12 cm. and Nº 75-98, 16x16 cm. In the first set of plates a field of 1ᵒ x 1ᵒ was investigated and in the latter set a field was of 2ᵒ x 2ᵒ, the cluster being always at the center. The region investigated was subdivided into cells of 10' x 10'. As usual, every care was taken in order to absolutely avoid any fake discovery due tu human error or to a plate defect.