| The Extragalactic Distance Scale Key Project I. The Discovery Of And A New Distance To M81 Using The (1997) | |||||||||||||||
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| We report on the discovery of 30 new Cepheids in the nearby galaxy M81 based on observations using the Space Telescope The periods for these lie in the range of 10 to 55 days, based on 18 independent epochs using the HST wide-band filter. The HST and data have been transformed to the Cousins standard V and magnitude system using a ground-based calibration. Apparent period-luminosity relations at V and were constructed, from which apparent distance were measured with respect to assumed values of = 18.50 mag and E(B- = 0.17 mag for the Large Cloud. The difference in the apparent V and yields a measure of the difference in the total mean extinction between the M81 and the samples. Our data indicate a total mean extinction to the M81 sample of E(B- = 0.11 msg. The true distance modulus to M81 is determined to be 27.80 0.20 mag, corresponding to a distance of 3.63 0.34 Mpc. These data illustrate that with an optimal (power-law) sampling strategy, the provides a powerful tool for the discove... | |||||||||||||||
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