Precision uvbyCa H \beta photometry of the metal-deficient , old open cluster , NGC 2506 , is presented .
The survey covers an area 20 \arcmin \times 20 \arcmin and extends to V \sim 18 for b - y and H \beta and to V \sim 17.0 for c _ { 1 } and hk .
For V brighter than 16.0 , photometric scatter among the indices leads to the recovery of 6 known variables within the cluster core and 5 new variables in the outer 5 \arcmin of the survey field .
Proper motions , radial velocities , and precise multicolor indices are used to isolate a highly probable sample of cluster members from the very rich color-magnitude diagram ( CMD ) .
From 257 highly probable members at the cluster turnoff , we derive a reddening estimate of E ( b - y ) = 0.042 \pm 0.001 ( E ( B - V ) = 0.058 \pm 0.001 ) , where the errors refer to the internal standard errors of the mean .
[ Fe/H ] is derived from the A/F dwarf members using both m _ { 1 } and hk , leading to [ Fe/H ] = -0.296 \pm 0.011 ( sem ) and -0.317 \pm 0.004 ( sem ) , respectively .
The weighted average , heavily dominated by hk , is [ Fe/H ] = -0.316 \pm 0.033 .
Based upon red giant members , we place an upper limit of \pm 0.010 on the variation in the reddening across the face of the cluster .
We also identify two dozen potential red giant cluster members outside the cluster core .
Victoria-Regina isochrones on the Strömgren system produce an excellent match to the cluster for an apparent modulus of ( m - M ) = 12.75 \pm 0.1 and an age of 1.85 \pm 0.05 Gyr .