Constraining the parameters of globular cluster NGC 1904 from its variable star population

This paper presents the analysis of 11 nights of V and I time-series observations of the globular cluster NGC 1904. Using this, the authors searched for variable stars in this cluster and attempted to refine the periods of known variables, making use of a time baseline spanning almost 8 years. The authors used difference imaging to reduce data to obtain high-precision light curves of variable stars. The authors then estimated the cluster parameters by performing a Fourier decomposition of the light curves of RR Lyrae stars for which a good period estimate was possible. Out of 13 stars previously classified as variables, the authors confirm that 10 are bona fide variables. The authors also detect a new RR Lyrae variable, giving a total number of confirmed variable stars in NGC 1904 of 11. Using the Fourier parameters, The authors find a cluster metallicity ..., or ..., and a distance of 13.3 plus or minus 0.4 kiloparsec or 12.9 kiloparsec.(ProQuest: ... denotes formulae/symbols omitted.)