TheHubble Space TelescopeKey Project on the Extragalactic Distance Scale. XII. The Discovery of Cepheids and a New Distance to NGC 2541

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Abstract
We report the detection of Cepheids and a new distance to the spiral galaxy NGC 2541, based on data obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope (HST). A total of 25 exposures (divided into 13 epochs) were obtained using the F555W filter (transformed to Johnson V), and nine exposures were obtained (divided into five epochs) using the F814W filter (transformed to Cousins I). Photometric reduction of the data is performed using two independent packages, DoPHOT and DAOPHOT II/ALLFRAME, which give very good agreement in the measured magnitudes. A total of 34 bona fide Cepheids, with periods ranging from 12 to over 60 days, are identified based on both sets of photometry. By fitting V and I period-luminosity relations, apparent distance moduli are derived assuming a Large Magellanic Cloud distance modulus and mean color excess of μLMC = 18.50 ± 0.10 mag and E(B-V) = 0.10 mag, respectively. Adopting A(V)/E(V-I) = 2.45, we obtain a true distance modulus to NGC 2541 of μ0 = 30.47 ± 0.11 (random) ± 0.12 (systematic) mag (D = 12.4 ± 0.6 [random] ± 0.7 [systematic] Mpc), and a total (Galactic plus internal) mean color excess E(B-V) = 0.08 ± 0.05 (internal error) mag.
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