Abstract. A large scale survey of the Galactic center region in the C18 O(J = 1 → 0) transition is presented. This survey was obtained with the 1.2 m Southern Millimeter-Wave Telescope (SMWT) at the Cerro Tololo Interamerican Observatory (CTIO) near La Serena, Chile. It covers the region −1.• 05 ≤ l ≤ +3.• 6 and −0.• 9 ≤ b ≤ +0.• 75 with a grid spacing of 9 , i.e. the sampling is at full FWHP beamwidth. 357 positions were in total observed. After reviewing the instrumentation of the 1.2 m SMWT, the observing techniques, and the methods used in the data reduction, the data of the survey are presented and morphologically described. In addition, data of the HNCO(5 0,5 − 4 0,4 ) line are presented, which was also included in the large bandwidth of the spectrometer.12 CO(1 − 0) measurements performed for comparison purposes are presented and compared with other 12 CO results. The maps of the C 18 O(1 − 0) survey demonstrate that there are great differences between the distribution of the optically thin C 18 O(1 − 0) emission and the usually optically thick 12 CO(1 − 0) emission.

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.

Abstract. We present a survey of the 45 MHz radio continuum emission in the declination range +5• to +65• . The observations were made with the circular filled array of the Japanese Midle and Upper Atmosphere Radar with a half-power beam width of 3.• 6. The results are presented in sets of maps in galactic and equatorial coordinates (Epoch 1950).

Abstract. We present a survey of the 45-MHz continuum emission south of δ = +19.1• . The observations were made with a transit array having a beam 4.6• (α) × 2.4• (δ), full width at half maximum (FWHM). The results are given in sets of maps in galactic and equatorial coordinates (Epoch 1950).

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