Recalibration of the H$_{\bf -0.5}$ Magnitudes of Spiral Galaxies

Abstract

The H magnitude aperture data published by the Aaronson et al. collaboration over a 10-year period is collected into a homogeneous data set of 1731 observations of 665 galaxies. 96\% of these galaxies have isophotal diameters and axial ratios determined by the Third Reference Catalogue of Bright Galaxies (de Vaucouleurs et al. 1991), the most self-consistent set of optical data currently available. The precepts governing the optical data in the RC3 are systematically different from those of the Second Reference Catalogue (de Vaucouleurs, de Vaucouleurs and Corwin 1976), which were used by Aaronson et al. for their original analyses of galaxy peculiar motions. This in turn leads to systematic differences in growth curves and fiducial H magnitudes, prompting the present recalibration of the near-infrared Tully Fisher relationship. New optically-normalized H magnitude growth curves are defined for galaxies of types S0 to Im, from which new values of fiducial H magnitudes, H$\rm _{-0.5}^g$, are measured for the 665 galaxies. A series of internal tests show that these four standard growth curves are defined to an accuracy of 0.05 mag over the interval $\rm -1.5 \leq \log (A/D_g) \leq -0.2$. Comparisons with the Aaronson et al. values of diameters, axial ratios and fiducial H magnitudes show the expected differences, given the different definitions of these parameters. The values of H$\rm _{-0.5}^g$ are assigned quality indices; a value of 1 indicates an accuracy of $<$0.2 magnitude; Quality 2 indicates an accuracy of 0.2 to 0.35 mag; and Quality 3 indicates $>$0.35 mag. Revised values of corrected HI velocity widths are also given, based on the new set of axial ratios defined by the RC3.