NGC 1316 BVI images

We also present the first B-band SBF measurements of NGC1316 and use them together with the optical and near-IR SBF data to analyze the properties of field stars in the galaxy. We obtain m-M=31.59+/-0.05(stat)+/-0.14(sys.)mag, or d=20.8+/-0.5(stat)+/-1.5(sys.)Mpc. When placed in a consistent Cepheid distance scale, our result agrees with the distances from other indicators.

On the other hand, our distance is ~17% larger than the most recent estimate based on SNe Ia. Possible explanations for this disagreement are the uncertain level of internal extinction, and/or calibration issues. Concerning the stellar population analysis, we confirm the results from other spectro-photometric indicators: the field stars in NGC1316 are dominated by a component with roughly solar metallicity and intermediate age.

A non-negligible mismatch exists between B-band SBF models and data. We confirm that such behavior can be accounted for by an enhanced percentage of hot horizontal branch stars. Our study of the SBF distance to NGC1316, and the comparison with distances from other indicators, raises some concern about the homogeneity between the calibrations of different indicators.

If not properly placed in the same reference scale, significant differences can occur, with dramatic impact on the cosmological distance ladder. Our results on the stellar populations properties show that SBF data over a broad wavelength interval are an efficient means of studying the properties of unresolved systems in peculiar cases like NGC1316.