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Session 50 - Interstellar Medium I.
Display session, Thursday, January 08
Exhibit Hall,

[50.03] The WHAM H\alpha Sky Survey: Early Results

L. M. Haffner, R. J. Reynolds, S. L. Tufte, K. P. Jaehnig, J. W. Percival (U. Wisconsin--Madison)

The Wisconsin H-Alpha Mapper (WHAM) has been surveying the northern sky in H\alpha from Kitt Peak, Arizona since January 1997. Using a high-throughput, 15-cm diameter double-etalon Fabry-Perot spectrometer and a sensitive CCD detector, the WHAM survey provides the first calibrated, velocity-resolved map of H\alpha emission in our Galaxy. The WHAM survey data have one-degree angular resolution, 12 km s^-1 velocity resolution, a 200 km s^-1 velocity range (typically centered near the Local Standard of Rest), and are sensitive down to 0.1 R (EM \sim 0.2 cm^-6 pc). Remote operation and semi-automated procedures allow extremely efficient observations, averaging over 100 spectra per hour. The WHAM survey finally allows detailed comparisons of the Warm Ionized Medium to the other major components of the interstellar medium that have been previously surveyed. With over 85% of the sky above \delta = -20\arcdeg completed after the first year, we present selected regions of this new view of ionized gas in the Galaxy. A fresh look at well-studied regions examines the Orion-Eridanus complex and the X-ray bright Monogem Ring supernova remnant. Complex networks of faint, ionized filaments dominate this region of the sky and include an impressive, faint (1--2 R), \sim 50\arcdeg-long, 2\arcdeg wide vertical filament extending upwards perpendicular to the Galactic plane near l = 225\arcdeg.

This work is supported by the National Science Foundation.

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