| Abstract | Twenty-one Cepheids in NGC 3109, discovered by Sandage & Carlson [AJ, 96, 1599 (1988)], have been measured into a new photometric CCD sequence in B. A zero-point offset of 0.29 mag has been detected with respect to previous photographic photometry (CCD magnitudes being brighter). For 17 Cepheids also new V magnitudes are derived. It is found that NGC 3109 is {DELTA}(m - M)_0_ = 7.00+/-0.16 more distant than the Large Magellanic Cloud (LMC), assuming a galactic reddening E(B - V) = 0.08 for the LMC, and E(B - V) = 0.04 for NGC 3109. Adopting (m - M)^0^_LMC_ = 18.5 this yields a distance modulus (m - M)_0_ = 25.5+/-0.2 for NGC 3109. The new distance of 1.26+/-0.1 Mpc is 25% shorter than previously measured. A comparison of colors, amplitudes, and period-luminosity relations suggests remarkably similar properties for the Cepheids in the LMC, IC 1613, M33, and NGC 3109. |
