NGC4321 is a two-armed grand design spiral galaxy in the Virgo Cluster. HI emission line data with 15 arcsecond resolution from the VLA map the velocity field of the hydrogen gas in the disk of NGC4321. In a grand design spiral galaxy, the presence of a spiral density wave causes deviations from circular rotation in the gas. The observed velocity

We have carried out an analysis of the high resolution optical spectra of post-AGB candidates SAO 85766 (IRAS 18062+2410), SAO 34504 (IRAS 22272+5435), HD 187885 (IRAS 19500-1709), HD 331319 (IRAS 19475+3119), HD 168625 (IRAS 18184-1623) and IRAS 10215-5916. All these objects have far-infrared colors similar to planetary nebulae and proto-

A step in the analysis of the data from the GOLF (Global Oscillations at Low Frequency) instrument on SOHO (SOlar and Heliospheric Observatory, an ESA/NASA Mission) involves the calculation of the sensitivity of the GOLF signal to the velocity at each point on the solar surface. A successful model of this sort will permit the intercomparison of

The GOLF instrument provides a stable and continuous measurement of the intensity of spatially integrated sunlight in one wing of the sodium D lines. Because the detected radiation results from atomic scattering, the GOLF signal can be traced to an atomic reference wavelength. The planned operations were to involve a form of relative photometry

We describe our methods to validate the absolute calibration of the infrared (IR) radiometry of the Midcourse Space Experiment (MSX) Point Source Catalog, version 1.2 (PSC1.2). These are based upon stars drawn from our current all-sky network of absolute calibrators and upon other stars that also support the calibration of ESA's Infrared Space

We report the discovery of a new double-image quasar that was found during a search for gravitational lenses in the southern sky. Radio source PMN J1838-3427 is composed of two flat-spectrum components with separation 1.0", flux density ratio 14:1, and matching spectral indices in VLA and VLBA images. Ground-based BRI images show the optical