Given the large number of normal galaxies in the sample, we decided to present for each object the most relevant information on a single page of this Guide. An individual page contains, therefore, the following information:
The selection of spectra to be combined into the representative UV spectrum of the galaxy was done according to the following rules:
The two selected SW and LW spectra were then combined into a single representative UV spectrum of the object. Sometimes, the mean spectral energy density (SED) levels of the SW and LW spectra of the same object were very different from each other. A simple combination, e.g. by concatenation of the SW and LW spectra would then result in a step-like SED. This is clearly visible in some of the spectra displayed in the ULDA Access Guide No. 3 (Longo & Capaccioli 1992), e.g. A1223+4846.
To prevent such an occurence, we decided to bring the LW spectrum to the level of the SW so as to ensure a smooth linkage between the spectra. We averaged the flux density in a 50Å segment at the long wavelength end of the SW spectrum, and in a 50Å segment at the short wavelength end of the LW spectrum. The normalization constant was determined from these flux density averages. The difference between the two averages was added to the LW spectrum to bring it into smooth continuation of the SW spectrum, and is indicated on the spectral plot. This matching was not performed in cases when it would have driven any part of the LW spectrum to negative flux levels. Such cases can be noticed by the gap between the SW and LW spectra displayed on the relevant pages (e.g. IC1613). A marginal case, where the shift was from a spectrum at zero LW flux level, was for AOO ANON1244-53. In few a cases (e.g. NGC 1147) the LW spectrum seems contaminated by additional light between 1900 and 2200Å. In such cases, no flux-matching procedure was applied.
For some extended galaxies, much larger than the IUE entrance apertures, spectra were obtained at a number of physically different regions in the galaxy. When two spectra, one SW and the other LW, could be identified in the same location for such a region, one page was dedicated to the separate presentation of this information. Multiple pages are shown for the following galaxies: NGC 3034, NGC 3690, NGC 4449, NGC 4861, NGC 5236.
For some spectra, the aperture coordinates reported in the image header are incorrect and point to a region outside the target, while the spectra show a significant signal. For these spectra, a new aperture position was computed (Solano, E., private communication) based on the guide star position used by the Guest Observer. Table 2 lists the image number and the revised aperture position.
We emphasize here that the morphological type of an object included in this compilation is the one listed in LEDA. Perusing the contents of this INES Guide, we found that some objects with which we are familiar are obviously mis-classified in LEDA. Such an example is Mrk 49, an E galaxy in LEDA but which is really a compact, starbursting dwarf. It is possible that there are more such mis-classifications, but we have not attempted to sort them out. Along with the morphological type listed in Table 1, the numerical T-type associated with a galaxy should also change. We believe this change not to be significant when considering the statistical distribution of the normal galaxy population displayed here (cf., Figure 3).