[Special session talk]
The radio continuum sky has been surveyed at many frequencies and angular resolutions. However, ALFA's unparalleled combination of sensitivity, resolution, and mapping speed will provide critical new data for a wide range of cutting-edge continuum science. Areas of investigation include: (1) polarimetric constraints on the large-scale Galactic magnetic field, including the disk-halo interface; (2) magnetic field studies of supernova remnants (SNRs), molecular clouds, and H II regions; (3) 3-D Faraday tomography of the ambient magneto-ionic medium, including turbulent cascades; (4) high-resolution, total-intensity imaging of Galactic loops and spurs, low-surface-brightness SNRs, H II regions, and the general interstellar medium, with separation into thermal and nonthermal components by multiwavelength analysis; (5) an extremely sensitive point-source catalog, including polarimetry and variability constraints; and (6) characterization of the ``true'' Galactic synchrotron foreground, which is essential for CMB studies at higher frequencies. All of these topics will be addressed by the G-ALFA Continuum Transit Survey (GALFACTS), a 5-year effort to map the entire Arecibo continuum sky in all four Stokes parameters at the highest possible sensitivity, using a 1000-channel, 300-MHz bandwidth spectrometer to eliminate contamination by RFI and ``unwrap'' frequency-dependent Faraday rotation effects. Further information can be found at www.ras.ucalgary.ca/GALFACTS.
This work is supported by the National Astronomy and Ionosphere Center, which is operated by Cornell University under Cooperative Agreement with the National Science Foundation.