Galaxies Detected by the Dwingeloo Obscured Galaxies Survey

A. J. Rivers , P. A. Henning , R.C. Kraan-Korteweg ,, PASA, 16 (1), in press.

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Introduction

Approximately 25% of the optical extragalactic sky is obscured by the dust and high stellar density of the Milky Way (figure 1). Although diligent optical and infrared searches for galaxies narrow this "Zone of Avoidance", in the most heavily obscured regions near the Galactic plane, only radio surveys consistently reveal hidden galaxies. Radio galaxy searches near the Galactic plane can help to complete our knowledge of the nearby large scale structure and explore the connectivity of superclusters and voids across the ZOA.

A full survey of the northern ZOA has been recently completed using the Dwingeloo 25-m radiotelescope and the Westerbork array in total power mode. The survey region (30$^\circ$

$\leq \ell \leq$ 220$^\circ$ ; |b| $\leq$ 5$^{\circ}\!\!$.25; 0 $\leq$ V

LSR $\leq$ 4000 km s-1) was initially covered in a shallow search by the 25-m (5 min per pointing; rms noise per channel $\sigma_{ch}$=175mJy) for nearby, massive galaxies (Henning et al. 1998). Recently, a deeper survey sensitive to nearby dwarfs and to normal spirals at the survey limit has been completed by the 25-m and the Westerbork array in total power mode. Results from the portion of the deep survey completed by the 25-m are reported here. Interesting regions covered by DOGS include a portion of the Local Void, the nearby IC342/Maffei group of galaxies and the region of sky where the Local Supercluster crosses the Galactic plane.

Figure 1: A combined Galactic longitude vs. latitude plot of approximately 30,000 galaxies collected from the MCG, UGC, and ESO optical catalogs shows the "Zone of Avoidance" caused by dust in the Galactic plane. The spatial region covered by the Dwingeloo survey is indicated. The hatched region represents the spatial overlap with the Parkes ZOA survey.
\begin{figure} \centerline{\psfig{file=MCG+ESO+UGC.ps,height=12cm,width=10cm}} \end{figure}


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