Photometric Study of the v2 Cepheid in M13

Small amateur telescopes equipped with photometric filters and CCD cameras constitute a valuable tool for variable star research. In this regard, we have carried out a photometric campaign over last three years (May 2001-November 2003), centered on the globular cluster M13 (NGC 6205). In this work, we present the results obtained from the photometric analysis of the BL Her cepheid V2 data, that can be used to estimate the distance to M13 (8.0 kpc), as well as some physical features of the star (mean radius: about 13 solar radii, effective temperature: about 6630 K, mean absolute bolometric magnitude: -1.49, and mean luminosity of 316 times the solar luminosity).