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Aims. We study the Galactic large-scale synchrotron emission by generating a reliable all-sky spectral index map and temperature map at 45 MHz. Methods. We use our observations, the published all-sky map at 408 MHz, and a bibliographical compilation to produce a map corrected for zero-level offset and extragalactic contribution. Results. We present full sky maps of the Galactic emission at 45 MHz and the Galactic spectral index between 45 and 408 MHz with an angular resolution of 5• . The spectral index varies between 2.1 and 2.7, reaching values below 2.5 at low latitude because of thermal free-free absorption and its maximum in the zone next to the Northern Spur.

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Abstract. We present the data from a CO(J = 1 → 0) survey of the central region of our Galaxy. The observations were obtained with the 1.2-m Southern Millimeter-wave Telescope at Cerro Tololo Interamerican Observatory, Chile. This instrument has a full beam-width at half maximum (FWHM) of 8.8 at 115 GHz, the frequency of the observed transition. The survey covers a strip 4• wide in latitude along the galactic equator in the range −12• ≤ l ≤ +13• . The spatial sampling interval was 7.5 (0.85 beam-widths) for |b| ≤ 1• , and 15 (1.7 beamwidths) for 1• < |b| ≤ 2• . The velocity coverage allowed by the filterbank was of 333 km s −1 with a resolution of 1.3 km s −1 at 115 GHz. For the central few degrees (−4.5• < l ≤ 5 • ) where this velocity span was not wide enough, two spectra, taken with different velocities with respect to the local standard of rest (VLSR), were combined in order to cover the full range of the galactic center CO emission. The antenna temperature noise level of the spectra was ≤ 0.10 K (rms). The data are presented in a latitude-longitude spatial map and in sets of longitudevelocity and latitude-velocity diagrams. This survey combines the characteristics of being very sensitive and well sampled, and of having one of the widest and more homogeneous spatial coverage of the region within ∼ 2 kpc from the galactic center.

The analysis of type III bursts observed from the OGO-5 satellite between 3.5 MHz and 50 kHz (46 km) gives an empirical expression for the frequency drift rate as a function of frequency that is valid from 75 kHz to 550 MHz. Using this expression and some simplifying assumptions we obtain indirectly an empirical formula for the electron density distribution of the solar wind to 1 AU which is consistent with published values of electron density and with observed type II1 burst drift rates.

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Abstract.We have calculated the integrated flux densities of the different components of the Vela SNR between 30 and 8400 MHz. The calculations were done using the original brightness temperature maps found in the literature, a uniform criterion to select the background temperature, and a unique method to compute the integrated flux density. We have succeeded in obtaining separately, and for the first time, the spectrum of Vela Y and Vela Z. The index of the flux density spectrum of Vela X, Vela Y and Vela Z are −0.39, −0.70 and −0.81, respectively. We also present a map of brightness temperature spectral index over the region, between 408 and 2417 MHz. This shows a circular structure in which the spectrum steepens from the centre (Vela X) towards the periphery (Vela Y and Vela Z). X-ray observations show also a circular structure. We compare our spectral indices with those previously published.

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