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Session 80 - Star Clusters in the Milky Way.
Display session, Friday, January 09
The post--core-collapse globular cluster NGC 6681 (M70) is characterized by an intermediate metallicity ([Fe/H] = --1.5), a low reddening (E(B--V) = 0.06), and a blue horizontal branch (HB). STIS ultraviolet images of NGC 6681 have recently been obtained as part of the Servicing Mission Observatory Verification (SMOV) testing. The images were obtained in five ultraviolet filters (25MAMA, F25QTZ, F25SRF2, F25CN182, and F25CN270), and reach a typical limiting monochromatic magnitude of m(UV) \sim 22. Photometry of the blue HB stars in the far-ultraviolet (\sim 1600 Åimages is in good agreement with the WFPC2 Woods filter photometry of Watson et al.\ (1994, ApJL, 435, L55). The F25CN182 -- F25CN270 color-magnitude diagram shows a tight cluster of blue HB stars, a pronounced blue straggler sequence, and several white dwarf candidates.
Program listing for Friday