spectral index


Also found in: Wikipedia.

spectral index

The index, α, expressing how the flux density (S) of a radio source varies with frequency (ν). The spectrum is taken to be a power law so that either S ∝ να or S ∝ ν–α. Because α is frequently stated without its sign, it is important to be clear which definition is being used in every case. See also power-law spectrum; radio-source spectrum.
References in periodicals archive ?
Better correlations were found in the attempt to portray wheat yield and NDVI, by normalizing the spectral index by time (DFP INSEY) and degree-days (GDD INSEY), according to Raun et al.
We performed a noise analysis with Maximum Likelihood Estimation (MLE) and found that stations in Central and Northern Europe are characterized by spectral index between flicker and random-walk noise, while stations in Southern and Western Europe: between white and flicker noise.
Specifically, the researchers say that the value of the spectral index, which describes the initial ripples in the density of the cosmos, should be 0.
Tenders are invited for supply installation testing Commissioning of Bi Spectral Index Monitor (2 Nos.
In addition, an integral spectral index - yellow rust spectral index (YRSI) was constructed to quantitatively estimate the disease using the most sensitive bands in the visible (704 nm), NIR (1423 nm) and SWIR (1926 nm) regions.
One of the experimental results supporting this theory is the fact that the distribution of the number of flares observed in the hard X-rays is a function of the energy, following a power law with negative spectral index 1.
As regards the spectral index, the latest data release and analysis from the WMAP satellite (8) shows that [[eta].
The NDVI has been the most commonly applied spectral index for characterizing the vegetation of Arctic environments using various satellite sensors.
In the first part of the analysis we simultaneously estimate the velocity and amplitudes of the noise with integer spectral index and in the second part we estimate the spectral index.
Such conditions are: the existence of some coupling constants that guarantee the calculation in a perturbative regime, the relative weight of the one-loop and tree level contributions, the normalisation of the spectrum, the observed spectral index, and the minimal amount of inflation required to solve the horizon problem.
The simplest inflationary models predict that the scalar spectral index should be slightly less than 1, exactly as the WMAP team has found.

Full browser ?