Professor Ranjan Gupta
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Item A comparison of synthetic and observed spectra for G-K dwarfs using arti(Astron. Astrophys, 1967-01-18) Gulati, R.K; Gupta, Ranjan; Rao, N.KA library of synthetic spectra, based on Kurucz model atmospheres, has been used to compare the spectroscopic observations in thewavelength range 4850-5384 A by using statistical and supervised arti cial neural network methods. The effective temperatures assigned by these methods for G-K dwarfs are compared with those given in Gray and Corbally (1994) and found to be closely matching their calibration curve. This result provides a promising new technique for determination of fundamental stellar atmospheric parameters on the basis of comparison between the model generated synthetic spectra and observed stellar spectra.Item ULTRAVIOLET STELLAR SPECTRAL CLASSIFICATION USING A MULTILEVEL TREE NEURAL NETWORK(Elsevier Science Ltd, 1995-01-25) Gulati, R.K; Gupta, R; Gothoskar, P; et.alHere we present a pattern classification technique based on an Artificial Neural Network (ANN) in a multi-level tree configuration to classify ultraviolet stellar spectra from the IUE Low-Dispersion Spectra Reference Atlas. Preliminary results of this technique show that 94% of the spectra have been classified correctly with an accuracy of one sub-class. A conventional 9~2 minimization scheme has also been applied to the data to compare the classification obtained from these schemes with that of the IUE catalog classification.