11 research outputs found

    A survey of Radio Recombination Lines using Ooty Radio Telescope at 328 MHz in the Inner Galaxy

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    A survey of radio recombination lines in the Galactic plane with longitude 32o<l<+80o-32^o < l < +80^o and latitude b<±3ob<\pm3^o using Ooty Radio Telescope(ORT) at 328 MHz has been reported. ORT observations were made using a New Digital Backend(NDB) augmented to it recently. With NDB ORT had a beam of 2o.3×2o.2sec(δ)2^o.3 \times 2^o.2 sec(\delta) and a passband of \sim1 MHz in the spectral line mode. The above mentioned Galactic region was divided into 2o×2o\sim 2^o \times 2^o patches with the ORT beam pointed to the center. The ORT observations form a study of distribution of extended low-density warm-ionized medium(ELDWIM) in the inner Galaxy using H271α\alpha RL. By obtaining kinematical distances using VLSRV_{LSR} of the H271α\alpha RLs the distribution of ELDWIM clouds within the inner Galaxy has been deduced for the region given above.Comment: 28 pages, Published in The Astronomical Journal with minor difference

    Interference detection in gaussian noise

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    Interference detection in gaussian noise is proposed. It can be applied for easy detection and editing of interference lines in radio spectral line observations. One need not know the position of occurence or keep track of interference in the band. Results obtained on real data have been displayed.Comment: 10 pages, 11 figure

    Helium line detections from ELDWIM at 1.4 GHz

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    Helium line observations towards 11 Galactic positions using Westerbork Synthesis Radio Telescope(WSRT) have been reported. These observations were made towards nearby positions where already hydrogen lines were detected at sufficiently high intensity(\geq50mK) at 1.4 GHz. This approach gave a fair chance for the detection of helium line as well, keeping in mind the relative abundance(10%) of helium with respect to hydrogen. Care was also taken to avoid the presence of HII regions along the line of sight so that the line emission originates from the extended diffuse low density ionized component, ELDWIM of the Galaxy. The observations have resulted in the detection of helium line towards 5 positions out of 11 with signal to noise ratio(snr) >> 4σ\sigma. An attempt has been made to associate detection/non-detection of helium line to the presence of surrounding HII regions. A weighting scheme that accounts for nearby(<< 500pc) HII regions, their distances and other factors produces favourable results. It is seen from this weighting scheme that a higher weight favours the detection of helium line while lower weight is associated with non-detection. The idea is to correlate ionization of ELDWIM with the surrounding HII regions.Comment: 15 pages, 6 figures, 3 tables, Published with minor changes in The Astronomical Journa