DISTANCE AND TOTAL COLUMN DENSITY TO THE PERIODIC RADIO STAR LSI+61-DEGREES-303

We report new observations toward the periodic radio star LSI + 61-degrees-303 in the lines of H I at 21 cm and (CO)-O-18 at 2.7 mm. Using the kinematic method we interpret our H I observations in terms of the two-armed spiral shock model of Roberts [ApJ, 173, 259 (1972)] to derive a distance to LSI + 61-degrees-303 of 2.0 +/- 0.2 kpc. The results clearly show the presence of the Perseus arm shock and locate LSI + 61-degrees-303 between this shock and the more distant post-shock gas. In addition, by using the H I and (CO)-O-18 data we derive the total neutral and molecular gas column density along the line of sight toward LSI + 61-degrees-303.