AAS 207th Meeting, 8-12 January 2006
Session 170 Cosmology, Early Universe, Cosmic Distance Scale
Poster, Thursday, 9:20am-4:00pm, January 12, 2006, Exhibit Hall

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[170.02] Discovery of Cepheids and the Distance of NGC 5128 (Centaurus A)

J. Mould (NOAO), L. Ferrarese, P. B. Stetson (HIA), J. Tonry (IfA), J. Blakeslee (WSU)

We present a new distance to NGC 5128 based on Cepheid variables observed with the Hubble Space Telescope. Twelve F555W and six F814W epochs of cosmic-ray-split Wide Field Planetary Camera 2 observations were obtained. A final sample of 56 bona-fide Cepheids having well defined light curves was adopted, with periods ranging from 5 to 50 days. Light curves are displayed. Adopting a Large Magellanic Cloud distance modulus and extinction, we obtain a reddening-corrected distance modulus to NGC 5128 (based on analyses employing the DoPHOT and DAOPHOT software packages) of between 27.5 and 27.9 mag, depending on the slope of the reddening curve in the dust lane and other uncertainties. We find an average reddening of E(V-I)~ 0.6.

This work was supported by NASA through STScI.

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