  (Abridged) Gas and star velocity dispersions have been derived for four
circumnuclear star-forming regions (CNSFRs) and the nucleus of the spiral
galaxy NGC2903 using high resolution spectroscopy in the blue and far red.
Stellar velocity dispersions have been obtained from the CaII triplet (CaT)
lines at 8494, 8542, 8662A, using cross-correlation techniques while gas
velocity dispersions have been measured by Gaussian fits to the Hbeta line.
  The CNSFRs, with sizes of about 100 to 150pc in diameter, show a complex
structure at the Hubble Space Telescope resolution, with a good number of
subclusters with linear diameters between 3 and 8pc. Their stellar velocity
dispersions range from 39 to 67 km/s. These values, together with the sizes
measured on archival HST images yield upper limits to the dynamical masses for
the individual star clusters between 1.8 and 8.7 x 10$^6$ M$_\odot$ and upper
limits to the masses for the whole CNSFR between 4.9 x 10$^6$ and 4.3 x 10$^7$
M$_\odot$. ...
