NEUTRAL HYDROGEN ABSORPTION-MEASUREMENTS OF 4 DISTANT PULSARS AND THEELECTRON-DENSITY IN THE INNER GALAXY

We have used the VLA to measure neutral hydrogen absorption and emissi on spectra toward four distant low-latitude pulsars in the inner Galax y whose spectra have not been previously recorded. In two cases, there is also a second reasonably bright source in the main beam of the tel escope. We use the companion spectra plus all published H I absorption spectra in the direction of each pulsar to assist in the kinematic de termination of pulsar distances. We also derive limits on the main ele ctron density along each line of sight, and we find that even along pa ths toward the inner Galaxy, the average electron density does not exc eed similar to 0.1 cm(-3). We test the Taylor and Cordes (1993) Galact ic electron density model against our measured electron densities plus additional inner Galaxy values recently determined by Koribalski et a l. (1995), and conclude that no major corrections to the model are ind icated.