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The VLA FIRST survey is now in its second year. We have completed mapping over 1500 deg2 of the North Galactic Cap and present here the catalog of the 138,000 radio sources detected therein. We discuss the statistics of this new catalog including the two-point angular correlation function for all radio emitters, present our optical identification of 24,000 sources using the APM catalog, and report followup studies on radio variability, X-ray source identification, and our bright quasar sample.

Although we now know of quite a few WR-O star binary systems, only HD 193793 is well studied across the entire electromagnetic spectrum. Hence it affords us the best opportunity to test various models for the system against a wealth of observational data. In this paper we present the results of 8 years of monitoring the radio flux density from HD 193793 with the VLA. This database is unique both in terms of its dense coverage of an entire binary cycle and because it extends the radio coverage to 2 cm wavelength, a shorter wavelength than previously available. With this data we are able to simultaneously solve for the time dependent attenuation in the system and the intrinsic radio luminosity. The standard model of spherically symmetric colliding winds faces severe difficulties in explaining the observations. We conclude that the radio data are most readily interpreted in the context of a WR star wind which is confined to a disk. A disk model for the WR wind also provides a natural explanation for the sudden formation of dust just after periastron.

The existence of a rapidly spinning, magnetized, neutron star at the center of the Crab Nebula is revealed in the soft X-ray band both by the pulsed point source coincident with the pulsar and through the strong, diffuse, synchrotron emission of the nebula itself. Recent Einstein observations have shown that in three other cases (Vela, 3C58, and CTB80), point plus extended Crab-like emission is associated with putative young neutron stars in supernova remnants. In addition, we have recently discovered evidence for point and extended X-ray emission from older, isolated radio pulsars. However, for the majority of young SNR, no such emission is observed. Since any synchrotron nebula emission is presumably isotropic and depends only on the ambient magnetic field strength and the energy-loss rate of the central neutron star, we can use these data to set stringent limits on the initial spin periods, magnetic fields, and/or the existence of young pulsars in historical SNR. The implication of these results for Crab-like remnant evolution and neutron star production will be discussed.

We have made observations with the VLA at 2, 6, and/or 20 cm of 10 stars: P Cygni, Cyg OB2 No. 12, MWC 349, V1016 Cyg, LkHα 101, HM Sge. Vy 2–2, T Tau, HD 193793, and V410 Tau. Visibility functions have been calculated to study the spatial structure of each source. Most sources appear to be stellar winds; however, some interesting anomalies were discovered. The data and model fits are shown, and the results are discussed.

The X-ray properties of the supernova remnant G 29.7 – 0.3 are discussed based on spectral data from the EXOSAT satellite. In the 2 to 10 keV range a featureless power-law spectrum is obtained, the best-fit parameters being: energy spectral index α -0.77, hydrogen column density on the line of sight NH= 2.3.1022 cm-2. The incident X-ray flux from the source is (3.6 ± 0.1) 10-11 erg cm-2 s-1 in the 2 to 10 keV range corresponding to an intrinsic luminosity of about 2.1036 erg s-1 for a distance of 19 kpc. The source was not seen with the imaging instrument thus constraining the hydrogen column density to be NH = (3.3 ± 0.3) 1022 cm-2 and the energy spectral index α = 1.0±0.15. This new observation is consistent with emission by a synchroton nebula presumably fed by an active pulsar. An upper limit of ~ 1.5% for the pulsed fraction in the range of periods 32ms to 104 s has been obtained.