Distances to the high-Galactic latitude molecular clouds G192-67 and MBM 23-24

We report on distance determinations fbr two high-Galactic latitude cloud c omplexes, G192-67 and MBM 23-24. No distance determination exists in the li terature for either cloud. Thirty-four early-type stars were observed towar d the two clouds, more than half of which have parallaxes measured by the H ipparcos satellite. For the remaining stars, we have made spectroscopic dis tance estimates. The data consist of high-resolution echelle spectra center ed on the Na I :D lines and were obtained over six nights at the Coude Feed telescope at Kitt Peak National Observatory. Interstellar absorption lines were detected toward some of the stars, which enabled estimates of the dis tances to the clouds of 109 +/- 14 pc for G192-67 and 139 +/- 33 pc for MBM 23-24. We discuss the relationship of these clouds to other ISM features s uch as the Local Hot Bubble and the local cavity in neutral hydrogen.