  For decades, the grand-design SAB spiral galaxy NGC 5248 has been postulated
to host a short bar of semi-major axis 22" (1.6 kpc). From dynamical and
morphological arguments, we argue, however, that its spiral structure is being
driven by a large-scale bar whose corotation radius lies at around 115" (8.6
kpc).Our estimate is based partially on a deep R-band image which reveals that
the feature previously thought to be an inclined disk is in fact an extended
stellar bar. The bar is embedded within a fainter outer disk visible out to a
radius of 230" (17.2 kpc). The bar has a deprojected ellipticity of 0.44 and a
semi-major axis of 95" (7.1 kpc). The classical grand-design spirals of NGC
5248, prominent in B, R, and K light, lie on the leading edge of the
large-scale stellar bar and are accompanied by concave dust lanes out to at
least 70". The offset between the dust and young stars is consistent with our
understanding of gas flows in barred galaxies, where shocks along the leading
edges of a moderately strong bar compress the gas to form massive young stars.
While in many strongly barred galaxies, optical spiral arms are prominent
outside the bar but not within it, NGC 5248 illustrates how intense star
formation along a moderately strong bar can lead to conspicuous open spiral
arms within the bar itself. NGC 5248 also provides a clear example of how a
large-scale stellar bar embedded within a faint outer optical disk can be
misidentified as an inclined disk when imaging studies lack the sensitivity to
detect the actual outer disk. We discuss the implications for the estimated bar
fraction at higher redshifts.
