| Abstract | We present Isaac Newton Telescope B and V CCD observations of deep photometric sequences in the vicinity of Cepheid variable stars in three nearby galaxies - M31, M33 and NGC 2403. We have also checked the photometry of the brightest stars in M81 and its dwarf companion, Holmberg IX. We use our data, combined with other recent results, to re-analyse the Cepheid distances to these galaxies. For M31, we find agreement with the B photometry of Baade & Swope for B < 22^m^. However, correcting for a slight scale error in V, we find that the M31 Cepheids may be less reddened than previously thought. We obtain μ_AB_ = 24.56 +/- 0.12 and μ_AV_= 24.62 +/- 0.10, for the 10 brightest Cepheids of M31. In M33 there is evidence that the corrections required to the Hubble magnitude scale may vary with position across the galaxy. Combining our value of μ_A_B = 24.8 +/- 0.1 with I-band data from other authors also suggests low reddening for the M33 Cepheids. For NGC 2403, we find that Tammann & Sandage's photometry shows a large scatter at faint magnitudes, particularly in the V-band. Also, stars with V > 21.25^m^ are too red in B- V We obtain μ_AB_ = 27.71 +/- 0.14 and μ_AV_= 27.31 +/- 0.12. However, since the I-band modulus lies between these two values, the reddening of the NGC 2403 Cepheids is still uncertain. Finally, we find reasonable agreement with the B and V photometry of Sandage in M81 and Holmberg IX, but major unexplained discrepancies exist between ourselves and other CCD observations in Holmberg IX. Our corrected distance moduli for the four calibrating galaxies suggest M_H_ = - 1 0.3(log V_21_ - 2.5) -21.4 for their infrared Tully-Fisher relation, with a scatter of +/- 0.44^m^. |
