SIMBAD references

This paper is the first of a series (Longhetti et al., 1998A&AS..130..267L, 1998b, Paper III) dedicated to the study of the star formation history in early-type galaxies which show fine structures and/or signatures of interaction. It presents nuclear line-strength indices for a sample composed of 21 shell galaxies, from the Malin & Carter (1983ApJ...274..534M) southern survey, and 30 members of isolated interacting pairs, from the Reduzzi & Rampazzo (1995ApL....30....1R) catalogue, located in low density environments. The spectral range covers 3700Å<λ<5700Å at 2.1Å FWHM resolution. We measure 16 red (λ>4200Å) indices defined by the Lick Group. Measures have been transformed into the Lick-IDS ``standard'' system. The procedure has been tested on a set of 5 elliptical galaxies selected from the Gonzalez (1993, Ph.D. thesis) sample. We derive also three blue (λ<4200) indices, namely {DELTA}(4000Å) defined by Hamilton (1985), H+K(CaII) and Hδ/FeI defined by Rose (1984AJ.....89.1238R, 1985AJ.....90.1927R). Blue indices are correlated to the age of the last starburst occurred in a galaxy Leonardi & Rose (1996AJ....111..182L). The determination of these indices, the estimate of the measurement errors and the correction for the galaxies velocity dispersions are discussed in detail. In the Appendix A we present the indices for a set of hot stars (T>10000K) which may be used for extending W92 fitting functions toward high temperatures.