THE ABSOLUTE MAGNITUDES OF RR LYRAES FROM HIPPARCOS PARALLAXES AND PROPER MOTIONS

We have used HIPPARCOS proper motions and the method of Statistical Pa rallax to estimate the absolute magnitude of RR Lyrae stars. In additi on we used the HIPPARCOS parallax of RR Lyrae itself to determine it's absolute magnitude. These two results are in excellent agreement with each other and give a zero-point for the RR Lyrae M-v,[Fe/H] relation of 0.77+/-0.15 at [Fe/H]=-1.53. This zero-point is in good agreement with that obtained recently by several groups using Baade-Wesselink me thods which, averaged over the results from the different groups, give s M-v = 0.73+/-0.14 at [Fe/H]=-1.53. Taking the HIPPARCOS based zero-p oint and a value of 0.18+/-0.03 for the slope of the M-v,[Fe/H] relati on from the literature we find firstly, the distance modulus of the LM C is 18.26+/-0.15 and secondly, the mean age of the Globular Clusters is 17.4+/-3.0 GYrs. These values are compared with recent estimates ba sed on other ''standard candles'' that have also been calibrated with HIPPARCOS data. It is clear that, in addition to astrophysical problem s, there are also problems in the application of HIPPARCOS data that a re not yet fully understood.