NEAR-INFRARED STELLAR PHOTOMETRY OF THE M31 SPIRAL ARM AROUND OB ASSOCIATION A24

Deep high-resolution JHK images of a 2' x 2' held around the OB associ ation A24 near the 7 kpc spiral arm in M31 were measured to yield phot ometric data of more than 3000 stars with the faintest magnitude being J = 21.3, H = 20.5, and K = 19.6. The photometric data for the 1037 s tars that are brightest in the K band are presented. Judging from the color-magnitude and the two-color diagrams, we find that the majority of the observed stars are AGE stars including large-amplitude variable s. They are distributed smoothly over the observed field, and we find no clear evidence of varying extinction over the field for these red s tars. The present sample includes bright AGE stars of M-k less than or equal to -8 and about 30 young blue objects of(J-H) < 0.75 that are b righter than M-J similar or equal to -6.5.