... 33

FITS files for Fig. 1 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/472/785

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... Tabatabaei

Member of the International Max Planck Research School (IMPRS) for Radio and Infrared Astronomy at the Universities of Bonn and Cologne.

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... telescope

The 100-m telescope at Effelsberg is operated by the Max-Planck-Institut für Radioastronomie (MPIfR) on behalf on the Max-Planck-Gesellschaft.

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... (VLA

The VLA is a facility of the National Radio Astronomy Observatory. The NRAO is operated by Associated Universities, Inc., under contract with the National Science Foundation.

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... I S

We refer to the arm notation of Humphreys & Sandage (1980); I N to V N for the northern and I S to V S for the southern arms.

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...Gordon et al. (1999)

They observed M 33 with the VLA and WSRT at 1.4 GHz and measured the flux density of point sources, but missed the extended emission.

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