The DiskMass Survey. I. Overview

We present a survey of the mass surface density of spiral disks, motivated by outstanding uncertainties in rotation-curve decompositions. Our method exploits integral-field spectroscopy to measure stellar and gas kinematics in nearly face-on galaxies sampled at 515, 660, and 860 nm, using the custom-built SparsePak and PPak instruments. A two-tiered sample, selected from the UGC, includes 146 nearly face-on galaxies, with B <14.7 and disk scale lengths between 10 and 20 arcsec, for which we have obtained Hα velocity fields; and a representative 46 galaxy subset for which we have obtained stellar velocities and velocity dispersions. Based on re-calibration of extant photometric and spectroscopic data, we show that these galaxies span factors of 100 in LK (0.03 <L/L* K