CCD photometry of variable stars in the field of the globular cluster NGC 6397

The $\rm 13.6\, \times\, 13.6\ arcmin^{2}$ field including the central part of the globular cluster NGC 6397 was surveyed in a search for short-period variable stars. We obtained light curves for 6 close binaries, 2 SX Phe stars and 1 RR Lyrae variable, 7 of which are new discoveries. Both identified SX Phe variables are likely members of the cluster. One of the identified eclipsing binaries is most probably a field star while for the remaining 5 binaries our data do not preclude cluster membership. A $V\rm\ vs$. $B-V$ color-magnitude diagram extending from the tip of the red giant branch to below the main-sequence turnoff is presented