[en] High-resolution (about 4 arcsec) radio observations of 11 small-diameter Galactic plane radio sources have been made with the VLA in a search for young but distant Galactic supernova remnants. The sources were selected on the basis of infrared to radio flux-density limits or ratios similar to those of known Galactic remnants. None of these appear to be a young shell SNR; five are compact radio sources, the other six show no evidence for the limb-brightened edges that would be expected if the sources were small-angular-size (less than about 3 arcmin) shell remnants. 20 refs

[en] Observations of the Cygnus Loop made at 408 MHz are presented. Radio spectral variations within the remnant are revealed by comparing the new observations with existing data taken at 2.695 GHz. The bright northeastern arc of the Cygnus Loop has a radio spectral index alpha of roughly 0.35, whereas the southern portion of the remnant generally shows steeper spectra, with alpha up to roughly 0.55. There is probably a portion of the faint radio emission from the northeastern arc that has a flatter spectrum than the brighter radio emission nearby. These differences are discussed in relation to mechanism for producing radio emission in SNRs and to the overall structure of the remnant. The observation confirm that there is faint radio emission outside the bright limb-brightened shell of the remnant, but this is limited to the west only. The faint halo of X-rays around the remnant is discussed and interpreted as originating from dust scattering. 55 refs

[en] Observations at 408 MHz of two extended features corresponding to objects in Lynds' (1965) catalog of bright nebulae are presented. These are LBN 140.77 - 1.42, which corresponds to a linear radio ridge roughly 2 deg in extent that is approximately perpendicular to the Galactic plane, and LBN 139.57 + 2.70, which shows a partial radio ring roughly 12 arcmin in radius. The radio emission from LBN 140.77 - 1.42 has a thermal spectrum, and it coincides with the western edge of a large spur that is evident in atomic hydrogen in the Perseus arm. Part of this spur is also evident in the infrared at all IRAS wavebands. Thus, LBN 140.77 - 1.42 appears to be a remarkably large-scale ionization front penetrating a large interstellar cloud. The nature of LBN 139.57 + 2.70 is not clear. 37 refs

[en] The selection effects that apply to the identification of Galactic supernova remnants are reviewed together with the limitations that they impose on statistical studies. Emphasis is given to problems with recent discussions of the number, birthrate, and distribution of remnants within the Galaxy. The distribution of high-surface-brightness remnants is concentrated in a nuclear disk that is even more well-defined than that noted by van den Bergh 1988a,b. Also presented, as an appendix, are revisions to the catalog of Galactic supernova remnants presented in Green 1988. The revised catalog contains 174 remnants. 45 refs

[en] The IRAS low-resolution spectrum of IRAS 81344 - 0632, which may be associated with the proposed (Cowan et al., 1989) very young supernova remnant G25.5 + 0.2, is presented. This spectrum shows a red continuum, and the 12.8-micron Ne II forbidden line, and is similar to the spectra of known compact H II regions and planetary nebulae. This, together with other results, suggests that IRAS 18344 - 0632 and G25.5 + 0.2 are associated, and are a planetary nebula not a young supernova remnant, although it is difficult to reconcile this identification with all available observations. 15 refs

[en] Observations with the VLA of neutral hydrogen absorption towards the filled-centre supernova remnant G74.9 + 1.2 and the adjacent compact radio source 2013 + 370 are presented. These confirm the extragalactic nature of the compact source, and a distance of ∼ 12 kpc for G74.9 + 1.2. From a continuum map, an upper limit is placed on the surface brightness of any shell around the remnant. (author)

[en] This paper presents a follow-up study of a flux density limited sample of 102 compact radio sources observed in the first DRAO Galactic plane survey. These sources each have at least 250 mJy at 408 MHz and, almost all of them are extragalactic. The multi-frequency radio spectral properties of these sources are presented - generally from observations at 151, 408 and 4850 MHz - and some associations with the IRAS point sources are also discussed

[en] Sensitive observations made towards 16 supernova remnants in the 1.667-GHz OH line with the DRAO 26-m radio telescope are presented. These observations were made in a search for broad, asymmetric absorption features, such as that seen towards G189.1 + 3.0 (IC443), in order to identify remnants which are interacting with molecular clouds and producing shock-excited species. Absorption by shocked OH is indicated in the cases of G33.6 + 0.1 and G84.2 - 0.8. Useful constraints on distances to several remnants are also derived. (author)

[en] Observations of part of the Galactic plane centred on l = 140⁰, b = 0⁰ made with the DRAO Synthesis Telescope at 408 MHz and 1.42 GHz (both continuum and hydrogen line) as a part of a Galactic-plane survey are presented. At 408 MHz a circular region of radius 4⁰ has been mapped with a resolution of ≅ 3.8 x 3.4 arcmin² (NS x EW), which provides details of 282 compact radio sources down to a flux density of ≅ 50 mJy and reveals in considerable detail the extended emission in this region. At 1.42 GHz a circular region of radius 1⁰3 has been mapped in continuum emission with a resolution of ≅ 1.1 x 1.0 arcmin² (NS x EW), revealing 81 compact sources down to a flux density of ≅ 6 mJy. Hydrogen-line maps of a circular region of radius 1⁰, smoothed to angular and velocity resolutions of 2 arcmin and 8 km s^-1 respectively, are also presented. For both the continuum and the line maps, the Synthesis Telescope data have been combined with low-resolution single-antenna data to provide maps that are sensitive to emission on all scales down to the resolution of the Synthesis Telescope maps

[en] G70.68+1.20 is a small shell source, approx.20 arcsec in extent, which has recently been proposed as a very young galactic supernova remnant. 5-GHz observations with the 5-km telescope at a resolution of approx. 2x4 arcsec² (RAxDec) are presented, and discussed together with other radio, optical and IR data. These favour the interpretation that the source is thermal, rather than a young supernova remnant. (author)