IMAGING OF THE CENTRAL REGION OF IC-1805

The central regions of OB Associations are suitable for the study of t he initial mass function since the constituent stars have not had suff icient time to migrate far from their formation site or to evolve from the main sequence. This paper reports on CCD observations of the cent ral 7'X7' region of the OB cluster Ocl 352, located in the H II region IC 1805, that is within the association Cas OB6, which is in turn par t of the molecular cloud W4. Colors were determined for 160 stars in I C 1805 and this information allowed the initial mass function for the region to be determined. A weighted linear least-squares fit to this m ass function in the mass range 2.5-30 M(.), yields a slope of Gamma=-1 .38+/-0.19. This is similar to the slope (-1.25+/-0.17) determined usi ng the brighter stars identified in a larger region (50'x50') of IC 18 05 by Joshi & Sagar [JRASC, 77, 40 (1983)]. It is also close to the sl ope of the IMF determined by other modem studies of select OB clusters . A roll off in the number of low-mass stars is observed but this is a ttributed to incompleteness in this study's inventory of stars of mass less than 2.5 M(.) (C) 1995 American Astronomical Society.