Spectral Energy Distributions and Masses of 304 M31 Old Star Clusters
  This paper presents CCD multicolor photometry for 304 old star clusters in
the nearby spiral galaxy M31. Of which photometry of 55 star clusters is first
obtained. The observations were carried out as a part of the
Beijing--Arizona--Taiwan--Connecticut (BATC) Multicolor Sky Survey from 1995
February to 2008 March, using 15 intermediate-band filters covering 3000--10000
\AA. Detailed comparisons show that our photometry is in agreement with
previous measurements. Based on the ages and metallicities from Caldwell et al.
and the photometric measurements here, we estimated the clusters' masses by
comparing their multicolor photometry with stellar population synthesis models.
The results show that the sample clusters have masses between $\sim 3\times10^4
M_\odot$ and $\sim 10^7 M_\odot$ with the peak of $\sim 4\times10^5 M_\odot$.
The masses here are in good agreement with those in previous studies. Combined
with the masses of young star clusters of M31 from Wang et al., we find that
the peak of mass of old clusters is ten times that of young clusters.
