1. S. B. Holmes, P. Massey (Lowell Observatory) Detections Using data obtained with the MOSAIC 8k x 8k CCD at the 4-m Mayall telescope at KPNO, we have been able to sample the entire galaxy much deeper than earlier studies. New candidates, once spectroscopically confirmed, might then alter the WC/WN ratio. The IC10 field was observed using three different filters in order to determine Wolf-Rayet candidacy. Filters used include: the WC filter ( 4650), the WN filter ( 4690), & the CT filter ( 4750). Respectively, the filters detect the CIII 4650 line, the HeII 4686 line, & a clean continuum. A set of three, dithered images were taken in each of the three filters. The exposure time for each image was 30 minutes; i.e., 1.5 hrs per filter. The seeing was XXXX Purpose Acknowledgements Observations Analysis Future Work This research is supported by the National Science Foundation under grant AST-0093060. We plan to spectroscopically observe our new Wolf-Rayet candidates. Spectra will indicate which candidates are definite WC or WN stars, possibly changing the WC/WN ratio, and either bringing it into better accord with more normal galaxies, or telling us that the WC/WN ratio is high in starbursts. Figure 2. Potential WR candidates: Asterisks indicate new detections, squares are spectroscopically confirmed WR stars and diamonds are the “control field”. The smallest ellipse contains likely non-WR stars. Progressing in size, the next region contains 25 questionable candidates, followed by a larger region containing an additional 10 probable WR candidates. The largest region contains 6 high significance candidates. Figure 1. The WC/WN ratios for Local Group Galaxies: IC10 has a high WC/WN ratio based on the survey done by Massey & Armandoff (1995). Figure 3. Spatial distribution of candidates in IC10: Based on fig. 2, red denotes spectroscopically confirmed WR stars, light blue indicates the location of the 6 high significance candidates, dark blue denotes the 10 probable candidates, and green represents the 25 questionable candidates. The Discovery of New Wolf-Rayet Star Candidates in the Starburst Galaxy IC10 Photometry of the galaxy was done using the IRAF/daophot package and our own scripts and code. In order to preserve the photometric integrity of the individual chips within a Mosaic frame, chips were analyzed separately. In the case of IC10, the galaxy was confined to a single chip. An additional chip was used as a “control field”. We selected candidates based upon the magnitude differences between the continuum and emission-line filters. We used the photometric errors to judge if a magnitude difference was significant or not. Multiple detections were also considered a plus in constructing our final candidate list. All spectroscopically confirmed Wolf-Rayet stars were found. In addition, we have confirmed the candidacy of several stars proposed to be Wolf-Rayets by Royer et al (2001 A & A 366, L1) based upon their own interference filter imaging but never confirmed spectroscopically. The exceptions are their “WC9" candidates; none of these were detected in our survey, causing us to question their surprising result that late-type WCs were to be found in such a low metallicity system. Comparing our final numbers against the control field, we have found a minimum of 6 & a maximum of 41 new Wolf- Rayet stars (Figures 2 & 3). IC10 is a Local Group dwarf irregular galaxy described by Hubble (1936) as ``one of the most curious objects in the sky". Massey and Armandoff (1995) proposed that it is currently undergoing a starburst: despite its small size, it contains 15 spectroscopically confirmed Wolf-Rayet stars, which is a galaxy- averaged surface density that is as high as that found in young, massive OB associations. This is consistent with a comparison of the Hα luminosity to HI mass or blue light luminosity (Hunter and Gallagher 1986, Hunter 1993), which suggests a star- formation rate comparable to that of NGC 1569, a classical starburst irregular. However, the relative number of WC-type and WN-type Wolf-Rayet stars is surprising high given the galaxy's low metallicity (Figure 1). Does this suggest a peculiar initial mass function, or an extremely short burst of star formation? Or could previous studies simply missed some of the weaker-lined WNs? IC10 stacked image: Hα is denoted by red, V is denoted by green, B is denoted by blue.