A uvbyCaHbeta CCD Analysis of the Open Cluster Standard, NGC 752
  Precision uvbyCaHbeta photometry of the nearby old open cluster, NGC 752, is
presented. The mosaic of CCD fields covers an area ~42' on a side with internal
precision at the 0.005 to 0.010 mag level for the majority of stars down to
V~15. The CCD photometry is tied to the standard system using an extensive set
of published photoelectric observations adopted as secondary standards within
the cluster. Multicolor indices are used to eliminate as nonmembers a large
fraction of the low probability proper-motion members near the faint end of the
main sequence, while identifying 24 potential dwarf members between V=15.0 and
16.5, eight of which have been noted before from Vilnius photometry. From 68
highly probable F dwarf members, we derive a reddening estimate of E(b-y)=
0.025 +/- 0.003 (E(B-V) = 0.034 +/- 0.004), where the error includes the
internal photometric uncertainty and the systematic error arising from the
choice of the standard (b-y), Hbeta relation. With reddening fixed, [Fe/H] is
derived from the F dwarf members using both m_1 and hk, leading to [Fe/H] =
-0.071 +/-0.014 (sem) and -0.017 +/- 0.008 (sem), respectively. Taking the
internal precision and possible systematics in the standard relations into
account, [Fe/H] for NGC 752 becomes -0.03 +/-0.02. With the reddening and
metallicity defined, we use the Victoria-Regina isochrones on the Stromgren
system and find an excellent match for (m-M) = 8.30 +/- 0.05 and an age of 1.45
+/- 0.05 Gyr at the appropriate metallicity.
