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Session 4 - Low Luminosity AGN and Starburst Galaxies.
Display session, Monday, June 10
Tripp Commons,

[4.06] Radio Continuum Mapping of the Spiral Galaxy NGC 4258

D. Calle (Virginia Tech), S. D. Hyman (Sweet Briar College), K. W. Weiler (Naval Research Lab), S. D. Van Dyk (UC Berkeley), R. A. Sramek (NRAO/VLA)

We have combined numerous, short radio continuum observations of the Seyfert 1 galaxy NGC 4258 (M 106) made at 20 and 6 cm with the Very Large Array (VLA) to produce deep radio maps at these frequencies. These observations were originally taken for monitoring the radio supernova SN 1981K (Weiler et al. 1986, ApJ, 310, 790; Van Dyk et al. 1992, ApJ, 396, 195). The present analysis is analogous to our recent work on NGC 6946 (Hyman et al. 1993, BAAS 25, 1322) and on NGC 4321 (Hyman et al. 1994, BAAS 26, 1498) using observations taken for monitoring SN 1980K and SN 1979C, respectively. The maps we produce for NGC 4258 are of superior sensitivity (\sigma \simlt 0.02 mJy/beam at 6 cm) and spatial resolution (\sim 0.5" at 6 cm) to those previously published by other investigators (e. g., Turner amp; Ho 1994, ApJ, 421, 122; Cecil et al. 1995, ApJ, 452, 613). We present preliminary measurements and analyses of the nuclear region, the anomalous arms, and of detected thermal and nonthermal sources throughout the galaxy. We also make comparisons of our radio maps with existing data at other wavelengths and with the results of our analyses of NGC 6946 and NGC 4321.

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