High-resolution optical imaging of the core of the globular cluster M15
  with FastCam
  We present high-resolution I-band imaging of the core of the globular cluster
M15 obtained at the 2.5 m Nordic Optical Telescope with FastCam, a low readout
noise L3CCD based instrument. Short exposure times (30 ms) were used to record
200000 images (512 x 512 pixels each) over a period of 2 hours 43 min. The
lucky imaging technique was then applied to generate a final image of the
cluster centre with FWHM ~ 0".1 and 13" x 13" FoV. We obtained a catalogue of
objects in this region with a limiting magnitude of I=19.5. I-band photometry
and astrometry are reported for 1181 stars. This is the deepest I-band
observation of the M15 core at this spatial resolution. Simulations show that
crowding is limiting the completeness of the catalogue. At shorter wavelengths,
a similar number of objects has been reported using HST/WFPC observations of
the same field. The cross-match with the available HST catalogues allowed us to
produce colour-magnitude diagrams where we identify new Blue Straggler star
candidates and previously known stars of this class.
