The highest surface brightness of the UV continuum emission is located in the inner 1 arcsec. However, several knots are also detected along the inner spiral arm segments that we associated with the leading edge of the bar (Figure 3). The 1 arcsec structure at optical wavelengths (Figure 4a) is very similar to the UV structure (Figure 4b). The central UV continuum consists of several knots distributed in an asymmetric ring with a total span of 1 arcsec (310 pc) in the North-South direction, and 0.7 arcsec (220 pc) in the East-West direction. We have taken as the origin for the coordinate system of the UV image the point of maximum emission which is one of the knots in the ring (Figure 4b). We have used the similarity between them to register the images. However, the maximum in the optical image coincides with a weak UV knot located in the inner part of the ring at 0.2 arcsec West and 0.1 arcsec South of the zero point. This knot is presumably the nucleus of the galaxy. As in Mrk 477 (Heckman et al 1997) and other Seyfert 2 galaxies (Colina et al 1997), the nucleus appears to be heavily obscured at UV wavelengths, emitting only a small fraction of the total light at 2150 Å.
The total UV emission detected in our FOC frame is about 57% of that measured in the IUE spectrum. The emission from the ring is 26#26 erg s-1 cm-2 Å-1, or about 67% of the total FOC emission. The flux of the brightest knot is 27#27 erg s-1 cm-2 Å-1 and of the presumed nucleus is 28#28 erg s-1 cm-2 Å-1. The emission of this nuclear knot thus represents less than 6% of the total UV emission detected, and about 10% of the emission in the inner 1 arcsec.
The outer radius of the starburst (the inflection point in the curve of growth) is 0.75'', yielding re = 0.26 arcsec (80 pc), and 29#29. The Galactic extinction towards NGC 7130 is E(B-V)=0.046, derived assuming 30#30 (Bohlin 1975) and an HI column density of 31#31 cm-2 (Start et al 1992). This implies an extinction of 0.45 mag at 2150 Å. We defer our discussion of the intrinsic extinction associated with the nucleus to section 6 below.