G347.3-0.5 (RX J1713.7-3946) is a member of the new class of shell-type Galactic supernova remnants (SNRs) that feature non-thermal components to their X-ray emission. We have analyzed the X-ray spectrum of this SNR over a broad energy range (0.5 to 30 keV) using archived data from observations made with two satellites, the Röntgensatellit (ROSAT ) and the Advanced Satellite for Cosmology and Astrophysics (ASCA), along with data from our own observations made with the Rossi X-ray Timing Explorer (RXTE ). Using a combination of the models EQUIL and SRCUT to fit thermal and non-thermal emission, respectively, from this SNR, we find evidence for a modest thermal component to G347.3-0.5's diffuse emission with a corresponding energy of kT ≈ 1.4 keV. We also obtain an estimate of 70 TeV for the maximum energy of the cosmicray electrons that have been accelerated by this SNR.

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We describe the H i component of the Southern Galactic Plane Survey (SGPS). The SGPS is a large-scale project to image at arcminute resolution the H i spectral line and 21 cm continuum emission in parts of the plane of the Milky Way. The survey covers Galactic longitudes 253 l 358 and latitudes jbj 1N5 (SGPS I), plus a first quadrant extension covering 5 l 20 and jbj 1N5 (SGPS II ). The survey combines data from the Australia Telescope Compact Array and the Parkes Radio Telescope for sensitivity to angular scales ranging from 2 0 to several degrees. The combined data cover 325 deg 2 and have an rms sensitivity of 1.6 K. Here we describe the H i observations and data reduction in detail and present examples from the final data products. The complete data set is publicly available through the Australia Telescope National Facility's H i Surveys archive. This data set provides an unprecedented view of the neutral component of interstellar hydrogen in the inner Milky Way.

We present the HIPASS Bright Galaxy Catalog (BGC), which contains the 1000 H i brightest galaxies in the southern sky as obtained from the H i Parkes All-Sky Survey (HIPASS). The selection of the brightest sources is based on their H i peak flux density (S peak k116 mJy) as measured from the spatially integrated HIPASS spectrum. The derived H i masses range from $10 7 to 4 ; 10 10 M . While the BGC (z < 0:03) is complete in S peak , only a subset of $500 sources can be considered complete in integrated H i flux density (F H i k 25 Jy km s À1 ). The HIPASS BGC contains a total of 158 new redshifts. These belong to 91 new sources for which no optical or infrared counterparts have previously been cataloged, an additional 51 galaxies for which no redshifts were previously known, and 16 galaxies for which the cataloged optical velocities disagree. Of the 91 newly cataloged BGC sources, only four are definite H i clouds: while three are likely Magellanic debris with velocities around 400 km s À1 , one is a tidal cloud associated with the NGC 2442 galaxy group. The remaining 87 new BGC sources, the majority of which lie in the zone of avoidance, appear to be galaxies. We identified optical counterparts to all but one of the 30 new galaxies at Galactic latitudes jbj > 10 . Therefore, the BGC yields no evidence for a population of ''free-floating'' intergalactic H i clouds without associated optical counterparts. HIPASS provides a clear view of the local large-scale structure. The dominant features in the sky distribution of the BGC are the Supergalactic Plane and the Local Void. In addition, one can clearly see the Centaurus Wall, which connects via the Hydra and Antlia Clusters to the Puppis Filament. Some previously hardly noticable galaxy groups stand out quite distinctly in the H i sky distribution. Several new structures, including some not behind the Milky Way, are seen for the first time.

We present new Faraday rotation measures ( RMs) for 148 extragalactic radio sources behind the southern Galactic plane (253 l 356 , jbj 1:5 ), and use these data in combination with published data to probe the large-scale structure of the Milky Way's magnetic field. We show that the magnitudes of these RMs oscillate with longitude in a manner that correlates with the locations of the Galactic spiral arms. The observed pattern in RMs requires the presence of at least one large-scale magnetic reversal in the fourth Galactic quadrant, located between the SagittariusCarina and Scutum-Crux spiral arms. To quantitatively compare our measurements to other recent studies, we consider all available extragalactic and pulsar RMs in the region we have surveyed, and jointly fit these data to simple models in which the large-scale field follows the spiral arms. In the best-fitting model, the magnetic field in the fourth Galactic quadrant is directed clockwise in the Sagittarius-Carina spiral arm (as viewed from the north Galactic pole), but is oriented counterclockwise in the Scutum-Crux arm. This contrasts with recent analyses of pulsar RMs alone, in which the fourth-quadrant field was presumed to be directed counterclockwise in the Sagittarius-Carina arm. Also in contrast to recent pulsar RM studies, our joint modeling of pulsar and extragalactic RMs demonstrates that large numbers of large-scale magnetic field reversals are not required to account for observations.