THE DISTANCE TO 2 NEUTRAL HYDROGEN CLOUDS - THE HIGH-VELOCITY COMPLEX-A AND THE LOW-LATITUDE INTERMEDIATE-VELOCITY CLOUD

A lower limit to the distance of the high-velocity cloud (HVC) complex A of 4 kpc (z > 3 kpc) is derived. The HVC is detected toward the Sey fert galaxy Mrk 106 in Mg II lambda lambda 2796, 2803 absorption spect ra taken with Hubble Space Telescope (HST) proving that Mg+ is present in the cloud. It is not detected in the Mg II spectra of two stars, P G 0859 + 593 (distance 4 kpc) and PG 0906 + 597 (distance 0.7 kpc). Th e distances to the stars are derived by matching Stromgren photometry and intermediate-resolution spectroscopy with model stellar atmosphere s; they are estimated to be accurate to within I kpc. From a combinati on of Effelsberg data and Westerbork maps with 2' or 3' resolution we show that the H I column density and thus the Mg+ abundance in the dir ection of the two stars is sufficiently high for the nondetections to imply that the HVC is behind the stars. This distance limit can be use d to eliminate several recent models for complex A that-placed it near by. We also derive a distance bracket of 1.7 < d < 4 kpc (1.1 < z < 3 kpc) for an intermediate-velocity cloud (IVC) at velocities of about - 50 km s(-1). This IVC was named the Low-Latitude Intermediate-Velocity Arch by Kuntz & Danly and is seen between l = 120 degrees-160 degrees and b = 30 degrees-45 degrees.