We present the catalog of RR Lyrae stars from the 2.4 square degree of central parts of the Small Magellanic Cloud (SMC). The photometric data were collected during four years of the OGLE-II microlensing survey.
Photometry of every star was obtained using Difference Image Analysis (DIA)
method. The catalog contains 571 objects, including 458 RRab, 56 RRc
variables, and 57 double mode RR Lyr stars (RRd). Additionally we attach a
list of variables with periods between 0.18-0.26 days, which are probably
delta Scuti stars. Period, BVI photometry, astrometry, amplitude,
and parameters of the Fourier decomposition of I-band light curve
are provided for each object. We also present Petersen diagram for double
We found that the SMC RR Lyr stars are fairly uniformly distributed over the studied area, with no clear correlation to any location. The modal value of periods for RRab and RRc stars is 0.589 and 0.357 days, respectively. We noticed significant excess of stars with periods of about 0.29 day, which might be second-overtone RR Lyr stars (RRe). The mean extinction free magnitudes derived for RRab stars are 18.97, 19.45 and 19.73 mag for the I, V and B-bands, respectively.
All presented data, including individual BVI observations, are available from the OGLE Internet archive.
PLEASE cite the following paper when using the data or referring to these OGLE results:
Soszynski et al., 2002, Acta Astron., 52, 369.
Any comments about the data and the form of their presentation are welcome as they can improve the future releases of catalogs of variable stars detected by OGLE-II collaboration. Send your messages to this address.