Results 31 to 40 of about 152,938 (206)

REMARKABLE SPECTRAL VARIABILITY OF PDS 456 [PDF]

The Astrophysical Journal, 2010
We report on the highest to date signal-to-noise-ratio X-ray spectrum of the luminous quasar PDS 456, as obtained during two XMM-Newton orbits in September 2007. The present spectrum is considerably different from several previous X-ray spectra recorded for PDS 456 since 1998.
Behar, E, Mushotzky, R, Kaspi, S, Reeves, J, Turner, TJ, O'Brien, PT   +5 more
openaire   +3 more sources

OPTICAL MICROVARIABILITY IN QUASARS: SPECTRAL VARIABILITY [PDF]

The Astrophysical Journal, 2010
We present a method that we developed to discern where the optical microvariability (OM) in quasars originates: in the accretion disk (related to thermal processes) or in the jet (related to non-thermal processes). Analyzing nearly simultaneous observations in three different optical bands of continuum emission, we are able to determine the origin of ...
Ramirez, A., Dultzin, D., de Diego, J. A.   +2 more
openaire   +2 more sources

Study of Genetic Variation in Bermuda Grass along Longitudinal and Latitudinal Gradients Using Spectral Reflectance

Remote Sensing, 2023
Genetic variation among populations within plant species can have huge impact on canopy biochemistry and structure across broad spatial scales. Since canopy spectral reflectance is determined largely by canopy biochemistry and structure, spectral ...
Jingxue Zhang, Mengli Han, Liwen Wang, Minghui Chen, Chen Chen, Sicong Shen, Jiangui Liu, Chao Zhang, Jiali Shang, Xuebing Yan   +9 more
doaj   +1 more source

Editorial for Special Issue “Hyperspectral Imaging and Applications”

Remote Sensing, 2019
Due to advent of sensor technology, hyperspectral imaging has become an emerging technology in remote sensing. Many problems, which cannot be resolved by multispectral imaging, can now be solved by hyperspectral imaging.
Chein-I Chang, Meiping Song, Junping Zhang, Chao-Cheng Wu   +3 more
doaj   +1 more source

Variability and spectral variation of 3C 66A [PDF]

Astrophysics and Space Science, 2011
3C 66A was monitored by the BATC(Beijing-Arizona-Taipei-Connecticut) telescope from 2005 to 2008,1994 observations were obtained on 89 nights. Detailed research and analysis was performed on these observations in this paper. A long term burst occurred in the whole light curve.
Hu, Shao Ming, Wu, Jianghua, Guo, H. Y., Zhou, X., Zhang, X., Zheng, Y. G.   +5 more
openaire   +2 more sources

New spectral functions of the near-ground albedo derived from aircraft diffraction spectrometer observations [PDF]

, 2014
The airborne spectral observations of the upward and downward irradiances are revisited to investigate the dependence of the near-ground albedo as a function of wavelength in the entire solar spectrum for different surfaces (sand, water, snow) and under ...
C. A. Varotsos, C. Tzanis, Varotsos, C. A., Vasilyev, A. V., I. N. Melnikova, Cracknell, A. P., Melnikova, I. N., Tzanis, C., A. V. Vasilyev, A. P. Cracknell   +9 more
core   +1 more source

Synthesis of Synthetic Hyperspectral Images with Controllable Spectral Variability Using a Generative Adversarial Network

Remote Sensing, 2023
In hyperspectral unmixing (HU), spectral variability in hyperspectral images (HSIs) is a major challenge which has received a lot of attention over the last few years.
Burkni Palsson, Magnus O. Ulfarsson, Johannes R. Sveinsson   +2 more
doaj   +1 more source

Host Galaxies and the Spectral Variability of Quasars [PDF]

, 2001
Brightness variability of QSOs is associated with variations of the spectral energy distribution in the optical-UV range. The observed change of the spectral shape depends on the contribution of the host galaxy. Simulations, taking into account luminosities and spectra expected for the host galaxies, are compared with the observed spectral variability ...
VAGNETTI, FAUSTO, Trevese, D.
openaire   +3 more sources

Spectral Characteristics of Common Reed Beds: Studies on Spatial and Temporal Variability

Remote Sensing, 2016
Reed beds are the second largest producer of biomass in Olkiluoto Island. Quantitative information on the extent and amount of reed stands is an integral part of the biosphere assessment related to long-term safety analysis of nuclear fuel repository ...
Jyrki Tuominen, Tarmo Lipping
doaj   +1 more source

Spectral Simplicity and Asymptotic Separation of Variables [PDF]

Communications in Mathematical Physics, 2011
We describe a method for comparing the real analytic eigenbranches of two families of quadratic forms that degenerate as t tends to zero. One of the families is assumed to be amenable to `separation of variables' and the other one not. With certain additional assumptions, we show that if the families are asymptotic at first order as t tends to 0, then ...
Hillairet, Luc, Judge, Chris
openaire   +5 more sources