... galaxies

Appendix A is only available in electronic form at http://www.aanda.org

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... WHISP

Westerbork observations of neutral Hydrogen in Irregular and SPiral galaxies, see www.astro.rug.nl/~whisp/

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... Searle

For NGC 4013 the pixelsize quoted in van der Kruit & Searle (1982a) was incorrect by a factor 1.5, as discoverd by Bottema (1995). This correction has been applied.

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... I

The H I extends only 10 to 20% beyond $R_{\rm max}$ on the sky.

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... Nachthimmels

The Holmberg radius is a method to estimate the radius of an elliptical galaxy. It was named after the Swedish astronomer Erik Bertil Holmberg. The Holmberg radius is defined as the length of half the major axis out to the isophote (...) that encloses a surface brightness of $\mu_{\rm H}$ = 26.5 mag/arcsec². This is measured in the so-called B-Band (...). The Holmberg radius therefore shows the extent of a galaxy from which the majority of the light originates (26.5 mag corresponds to about 1 to 2 percent of the brightness of the night sky).

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... (pg) band

The transformation can be written as $B - m_{{\rm pg}} = 0.2 - 0.1( B - V)$(see Kormendy & Bahcall 1973; based on Arp 1961).

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