We present the first WFPC2 V , I photometry for the Sculptor Group galaxy NGC 300 in four fields ranging from the centre to the outer edge .
We have made the first measurement of the star formation histories in two disk fields : the oldest stars were born at similar epochs and formation activity increased but at different mean rates .
The main disk stellar population is predominantly old , consisting of RGB and AGB stars , based on a synthetic colour magnitude diagram analysis .
Z is found to have been more metal poor than 0.006 ( or 0.33 Z _ { \odot } ) with no evidence for significant change in the mean Z value over time in both disk fields .
In the central region , we find a dearth of bright stars with respect to the two disk fields that can not be explained by observational effects .
Taken at face value , this finding would agree with the Davidge ( 1998 ) report of suppressed star formation there during the past 10 ^ { 9 } yr with respect to his disk fields at larger radii ; but the possibility of significant central extinction affecting our finding remains .
We have also determined the first distance modulus estimate based on the tip of the red giant branch method : on the Cepheid distance scale of Ferrarese et al .
( 2000 ) we find ( m-M ) _ { \circ } = 26.56 \pm 0.07 ( \pm 0.13 ) mag ; and a similar value from the Cepheid-independent empirical method by Lee et al .
( 1993 ) , both in good agreement with the Cepheid distance determined by Freedman et al .
( 2001 ) .
A discrepancy between this and the theoretical calibration of the red giant branch tip magnitude method remains .
Finally , we report a newly detected young ( up to about 10 Myr ) stellar association of about average size ( \sim 140 pc ) in one of the disk fields .