The brightest UV emission is concentrated in the inner 39#39 arcsec ( 40#40 pc). Outside of this central structure we don't find any other knot of continuum emission in the FOC images. This central structure is resolved into several substructures, with a morphology very similar in the optical light (Figure 7a) and UV light (Figure 7b). Its overall 41#41 shape is aligned perpendicular to the bar. This subarcsec structure could be related to the inner Inner Lindblad Resonance. Here, we have taken as origin of the plot the point with highest surface brightness in the WFPC2 image. This point is located in middle of the 41#41 structure. We suggest that the nucleus of the galaxy is in this central structure seen in the UV image. However, the knot of highest UV surface brightness is at 0.2 arcsec East and 0.05 arcsec North of the nucleus.
The total FOC UV emission is only about a quarter of the IUE flux. If our sky estimate is decreased by its 42#42 uncertainty, then the total flux more than doubles becoming 43#43, or about 56% of the IUE flux. This suggests that much of the IUE flux may result from fairly low surface brightness emission. The central structure emits 44#44 erg s-1 cm-2 Å-1, this represents 66% of the FOC total detected emission. This flux is emitted mainly by the presumed nucleus ( 45#45 erg s-1 cm-2Å-1, 10% of the total emission) and the two extended knots of the 41#41 ( 46#46 erg s-1 cm-2 Å-1 per knot). The outer radius of the combined central structure is 0.51'' and it has re = 0.26 arcsec (55 pc) and 47#47 STmag arcsec -2. The Galactic extinction derived from an HI column density of 48#48 cm-2is E(B-V)=0.14. This implies a correction of 1.36 mag at 2150 Å due to our Galaxy alone.