Near-infrared and Stromgren photometry of the open clusters NGC 663, NGC 1502 and NGC 1893.

Observational data are presented regarding the three objects including near-IR JHK, Stromgren uvby, and H-beta photometry of the central regions. The intrinsic photometric colors of average main-sequence stars are taken from previous studies to examine the data with m1 vs. b-y, c1 vs. m1, beta vs. c1, J-H vs. H-K, and V-K vs. b-y diagrams. It is determined that the ages of and distance to NGC 663, NGC 1502, and NGC 1893 are respectively 9 x 10 exp 6 yr and 2.5 kpc, 5 x 10 exp 6 yr and 1.5 kpc, and 4 x 10 exp 6 yr and 4.3 kpc. The results indicate other parameters, and considerable differental reddening is noted across NGC 663. The total-to-selective extinction ratio is also examined showing that it is smaller than the galactic value towards NGC 663 and 1893 and significantly lower than the average value for the ISM in NGC 1502. It is concluded that the size distribution of the dust particles in the present line-of-sight has an inherent bias.