| The pulsar has always been the object which the astronomers pay attention to since itsdiscovery. Among the numerous research directions, studying on the spectral observations of thepulsars is one of the hot spots, and is also one of the most direct ways through which peopleunderstand the internal material constitution, the radiation mechanism and locate electromagneticenvironment of pulsars. The astrometry has entered a new stage by the development of VLBIwith its high angular resolution, which also greatly benefits the research of the pulsar.This paper consists of two parts. Based on the brief introduction of the pulsars’ basic attributesand research directions, the research on the fitting observation data of the pulsar spectrum withthe free-free absorption model are emphasized, and the current application situation,development requirements of VLBI technology in China are also detailed described anddiscussed.Based on the large sample of multi-frequency observation data, we select two different fittingmodels, giving priority to free-free absorption model, and fit the curves with the linear leastsquares method and nonlinear LM (Levenberg-Marquardt) algorithm, and finally analyze theapplicability of model and the factors that influence the error of the fitting parameters after thecomparison of the two models’ results. With the result we find there is no phenomenon such asturn-over in the spectrum of millisecond pulsar, and the figure of the curve fitting also showthere may be a turn-over at a low frequency.e-VLBI is a new result of development of contemporary VLBI which can obtain theobservation results quickly by transmitting its data with high speed communication network. Byanalyzing the technical characteristic, reviewing the development of e-VLBI, we elaborate thecurrent application situation in observation of pulsar and the orbit determination of spacecraft,and mainly discuss the future requirements of the arrangement of equipment in the old and newobservation stations. |
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