Galactic All Sky Survey



Projects underway led by the GASS team

Figure 1

Figure 1: A velocity slice of GASS data at vlsr=-43 km/s. This slice shows an abundance of features at local velocities including HI clouds in the lower halo. Some of these clouds appear isolated while others appear to be condensations of filaments.

The Origin and Nature of HI Clouds in the Lower Halo of the Galaxy
led by Alyson Ford, Swinburne University

Faint, discrete HI clouds near the Galactic plane have recently been observed using the Green Bank Telescope (Lockman, 2002). Distances to these clouds can be determined by looking towards tangent points of the inner Galaxy at velocities expected from Galactic rotation. This provides a huge advantage over most HI clouds by allowing us to determine their physical properties such as size and mass. The GASS data are being used to create a complete inventory of such clouds, along with a statistical evaluation of their physical properties. Figure 1 shows that these clouds are quite abundant and may be responsible for a considerable amount of HI mass in the lower halo.

A complete catalog of High Velocity Clouds in the Southern Sky
led by D. J. Pisano, West Virginia University

GASS provides sensitive, high angular and spectral resolution data for studying the nature and origin of HVCs. Work is underway to provide an updated catalog of high and intermediate velocity clouds (HVCs and IVCs), searching in particular for narrow line clouds and those close to Galactic velocities that would have been missed in previous catalogs. These clouds will be studied for information about their physical and spectral structure.