Photometry of New Globular Clusters in M 31 Sang

We present a progress report on Washington photometry of several hundred new globular cluster (GC) candidates in M31 which were recently found from our new CCD survey of GCs. Washington CMT1 filters we used are very efficient to survey extragalactic GCs and to estimate the metallicity of GCs. Preliminary color-magnitude diagrams and color-color diagrams of the new GC candidates and known GCs in M31 are obtained. M31 is the nearest giant spiral galaxy that contains more GCs than our Galaxy and all the other Local Group galaxies combined. Since there has been no CCD survey of GCs in M31 for the entire field of M31 (> 3 × 3), the luminosity function of M31 GCs in the present literature lacks data at the faint end compared to that of our Galaxy. Therefore, we have performed a new widefield CCD survey of GCs in M31 over the past few years (Lee et al. 2001). Here we present a preliminary Washington photometry of new GCs in M31 discovered recently in our new survey. Our photometry is based on the CCD images obtained using the KPNO 0.9m telescope + T2KA 2048×2048 pixel CCD (each 23.2× 23.2) with Washington C,M,T1 filters. We have derived the photometry of the objects in the CCD images using DAOPHOT II/ALLFRAME. New GC candidates in the list of objects with photometry were selected as follows. First, we plotted the color-magnitude and color-color diagrams of all the point sources detected in each field, and took the objects in the regions where GCs are supposed to be (Harris & Canterna 1977). Second, we performed the digital classification using three morphological classification parameters (wing moment r1, central concentration r−2, and magnitude difference between PSF fitted magnitude and aperture magnitude ∆ mag). Third, we performed visual