Optical photometry is presented for the quadruple gravitational lens PG1115+080. A preliminary reduction of data taken from November 1995 to June 1996 gives component "C" leading component "B" by 23.7 ± 3.4 days and -2components "A1" and "A2" by 9.4 days. A range of models has been fit to the image positions, none of which gives an adequate fit. The best fitting and most physically plausible of these, taking the lensing galaxy and the associated group of galaxies to be singular isothermal spheres, gives a Hubble constant of 42 km/s/Mpc for Ω = 1, with an observational uncertainty of 14%, as computed from the B − C time delay measurement. Taking the lensing galaxy to have an approximately E5 isothermal mass distribution yields H 0 = 64 km/sec/Mpc while taking the galaxy to be a point mass gives H 0 = 84 km/sec/Mpc. The former gives a particularly bad fit to the position of the lensing galaxy, while the latter is inconsistent with measurements of nearby galaxy rotation curves. Constraints on these and other possible models are expected to improve with planned HST observations.

We studied for duplicity the 167 F7-G8 IV or V primaries within 25 pc of the Sun according to their Hipparcos parallaxes and between declinations of À30 and +75 . We obtained an average of 13 coudé radial velocities with an accuracy of AE0.10 km s À1 . Combining these measures with published data, we obtained 39 single-lined and 12 double-lined binaries with orbital elements. This material will be combined in a later paper with the known visual binaries to derive the secondary mass frequencies.

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