Abstract:
Cepheids are the primary distance indicators for the external galaxies, so discovery of large number of Cepheid variables
in far-off galaxies offers a unique opportunity to determine the accurate distance of the host galaxy through their period-luminosity
relation. The Cousins R and I band photometric observations were carried out in the direction of M31 with the aim of detecting
microlensing events. The data was obtained with a 1-m telescope on more than 150 nights over the period between November 1998
and January 2002. The data was analysed using the pixel technique and the mean magnitudes of the Cepheids were determined by
correlating their pixel fluxes with the corresponding PSF-fitted photometric magnitudes.
Results. In the present study we report identification of short-period Cepheid variables in the M31 disk. We present a catalogue of
39 short-period (P < 15 days) Cepheids in a ∼13' × 13' region of the M31 disk and give positions and pulsation periods along with
their R and I bands photometric magnitudes wherever possible. Most of the Cepheids are found with R (mean) ∼ 20–21 mag, and the
dense phase coverage of our observations enabled us to identify Cepheids with periods as short as 3.4 days. The period distribution of
these Cepheids peaks at log P ∼ 0.9 and 1.1 days.
