1. BATC Multi-color Photometry of Open Cluster M48 Zhenyu Wu 8.11, 2005, Weifang

2. Open clusters in Milky Way Number of clusters: 1690 Clusters with Diameters: 1688 (99.9%) Clusters with Distances: 740 (43.8%) Clusters with Reddening: 721 (42.7%) Clusters with Ages: 608 (36.0%) Clusters with Dist,Redd.and Ages: 594 (35.1%) Clusters with Proper motions: 614 (36.3%) Clusters with Radial velocities: 227 (13.4%) Clusters with P.Motions + RVs: 217 (12.8%) Clusters with Dist,Ages,PMS and RVs 214 (12.7%) Clusters with Abundances: 131 ( 7.8%)

3. The basic parameters of M48 Distance: 530 pc — 770 pc E(B-V): 0.03 — 0.06 [Fe/H]: 0.0 — 0.1 Age: 0.30 Gyr — 0.40 Gyr

4. Observation BATC photometric system with 60/90 cm Schmidt telescope of NAOC 2048×2048 CCD, 58 ' × 58 ' field of view 13 filters are used: b, c, d, e, f, g, h, i, j, k, m, n, o, p

6. Theoretical model Padova 2000 model Age (Log(t)): 6.3 — 10.25 Metallicity Z: 0.0 、 0.0001 、 0.0004 、 0.001 、 0.004 、 0.008 、 0.019 、 0.03 Mass of stellar ： 0.15 － 120 M ⊙

7. Method SED fitting between observations and theoretical models Stellar sample: memberships of cluster The deviation of observation and model for each cluster star is calculated The total deviation of all cluster stars is calculated The basic parameters of cluster can be derived by search model for which the total deviation has the minimum

10. Error analysis 0.05 photometric error for each filter is assumed Error of Distance: 10pc Error of E(B-V): 0.01 Error of Log(t): 0.05 Error of [Fe/H]=0.0