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NICMOS Observations of Extragalactic Cepheids. I. Photometry Database and a Test of the Standard Extinction Law

L. M. Macri·D. Calzetti·W. L. Freedman·B. K. Gibson·J. A. Graham·J. P. Huchra·S. M. G. Hughes·B. F. Madore·J. R. Mould·S. E. Persson·P. B. Stetson
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Abstract

We present the results of near-infrared observations of extragalactic Cepheids made with the Near Infrared Camera and Multi-Object Spectrometer on board the Hubble Space Telescope. The variables are located in the galaxies IC 1613, IC 4182, M 31, M 81, M 101, NGC 925, NGC 1365, NGC 2090, NGC 3198, NGC 3621, NGC 4496A and NGC 4536. All fields were observed in the F160W bandpass; additional images were obtained in the F110W and F205W filters. Photometry was performed using the DAOPHOT II/ALLSTAR package. Self-consistent distance moduli and color excesses were obtained by fitting Period-Luminosity relations in the H, I and V bands. Our results support the assumption of a standard reddening law adopted by the HST Key Project on the Extragalactic Distance Scale. A companion paper will determine true distance moduli and explore the effects of metallicity on the Cepheid distance scale.

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L. M. Macri, D. Calzetti, W. L. Freedman, B. K. Gibson, J. A. Graham, J. P. Huchra, S. M. G. Hughes, B. F. Madore, J. R. Mould, S. E. Persson, P. B. Stetson. 2001-02-07. NICMOS Observations of Extragalactic Cepheids. I. Photometry Database and a Test of the Standard Extinction Law. https://doi.org/10.1086/319465

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