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Session 81 - Dwarf Galaxies.
Display session, Friday, January 09
Exhibit Hall,

[81.02] The Three Dimensional Shape of the Sagittarius Dwarf Galaxy

S. Lepri, M. Mateo, A. Layden, S. Lemley (U. Mich.), E. Olszewski (U. Ariz.), H. Morrison (CWRU)

The discovery of the Sagittarius Dwarf Galaxy (Sgr) in 1994 has provided a unique chance to observe the interaction of a dwarf satellite passing close to the Galactic Center. An understanding of this process is complementary to growing evidence that the Galactic halo is composed -- at least in part -- of accreted dwarfs. The proximity of the Sgr dwarf allows us to use RR Lyr stars to provide a three-dimensional view of the structure of the galaxy as it is torn apart by the Milky Way. We have obtained more than 300 CCD images, each containing in excess of 100,000 stars, in the V and I bands using the CTIO Schmidt telescope and the LCO 1m telescope. Our observations concentrated on 14 fields within Sgr. Photometric analyses of the images enable us to investigate them for RR_ab Lyraes. Selection of RR_ab Lyrs scattered throughout the galaxy and analysis of their characteristic light curves help us obtain precise relative distances that can be simultaneously corrected for differential reddening in the fields. We plan to map the three-dimensional shape of the galaxy and decipher its nearest side and direction of motion. We present our first results for one of the fields and update our progress on the other fields in Sgr.

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