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.

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Between 1994 July and 1997 February we monitored the optical spectrum of RX J0019.8]2156. This supersoft X-ray source is one of only two accreting white dwarfs in the Galaxy that are thought to be burning hydrogen on their surface as a consequence of a high rate of mass transfer from a binary companion. Accurate orbital ephemerides are derived from radial velocity measurements for the white dwarf, which are obtained from strong He II emission lines with a stable velocity semiamplitude of K \ 71.2^3.6 km s~1. We report the discovery of transient, low-velocity, bipolar jets. These jets are represented by redshifted-blueshifted pairs of emission lines from H and He II with an outÑow velocity of v cos (i) D 815 km s~1, where i is the binary inclination angle. When present, the jet lines seen in Ha also exhibit an orbital modulation of 71 km s~1, which strengthens the interpretation that this is the orbital velocity of the white dwarf and also indicates that the jets are oriented nearly perpendicular to the orbital plane. On most occasions, the H emission line proÐles are further altered by P Cygni absorption e †ects, and the strength of this absorption is also dependent on binary phase. We show that the jets and the P Cygni features have very di †erent temporal characteristics and binary phase dependence ; thus, we conclude that the outÑowing material and the absorbing wind must have essentially di †erent geometries. Finally, the measured mass function is combined with binary evolution models to suggest a limit on the inclination angle, i \ 40¡. A particular model invoked to explain a high rate of mass transfer requires 16¡ \ i \ 25¡. However, at such small inclination it is difficult to explain the large amplitude of the orbital light curve (D0.5 mag). Alternatively, the results could signify substantial vertical structure in the accretions disks of supersoft X-ray sources. By contrast, a simple model Ðt to the jet outÑow lines indicates an orbital inclination angle of 35¡ \ i \ 60¡.

ER UMa (PG 0943+521), VI159 Ori, and RZ LMi constitute a small recently recognized group of dwarf novae, called the RZ LMi stars or the ER UMa stars. They share many features of the SU UMa-type, but have shorter outburst cycles than had been known previously. Here we establish orbital periods, based on emission-line radial velocities, for ER UMa (0.06366±0.00003 d = 91.67±0.04 min) and VI159 Ori (0.06217801 ± 1.3X 10" 7 d = 89.5363± 0.0002 min). The precise orbital period for VI159 Ori depends on an extrapolation of cycle count from 1991 to 1994, which is slightly uncertain, but the daily cycle count is reasonably secure. These orbital periods are similar to those of the more common, less frequently outbursting SU UMa stars. As is generally the case, the orbital periods derived here are slightly shorter than the periods of photometric superhumps which appear in superoutburst. The superhump period excesses found here are compatible with, but marginally larger than, those seen in other SU UMa stars of similar period. While the empirical link between ER UMa stars and SU UMa stars is generally strengthened by these results, the trend toward slightly larger period excesses (if true) can be interpreted as a tendency for systems with larger mass ratios to develop larger mass-transfer rates at a given orbital period.