| Abstract | CCD photometry of the RR Lyrae variables in the SMC cluster NGC 121 gives a true distance modulus for the cluster of 18.86 +/- 0.07 mag if =0.6. Assuming the mean SMC distance to be the same as for NGC 121, then the difference in modulus between the LMC and the SMC, based on RR Lyraes alone, is 0.43 +/- 0.09 mag if RR Lyrae luminosities are independent of metallicity, or 0.31 +/- 0.10 mag if {DELTA}M_V_(RR)/{DELTA}[Fe/H] = 0.20. The latter estimate is in better agreement with the differential modulus found from Cepheids; however, a displacement between the mean distance of the SMC Cepheids and NGC 121 could provide an equally valid explanation for the difference. |
