50 research outputs found
Generating high-temporal and spatial resolution tir image data
No full textRemote sensing imagery to monitor global biophysical dynamics requires the availability of thermal infrared data at high temporal and spatial resolution because of the rapid development of crops during the growing season and the fragmentation of most agricultural landscapes. Conversely, no single sensor meets these combined requirements. Data fusion approaches offer an alternative to exploit observations from multiple sensors, providing data sets with better properties. A novel spatio-temporal data fusion model based on constrained algorithms denoted as multisensor multiresolution technique (MMT) was developed and applied to generate TIR synthetic image data at both temporal and spatial high resolution. Firstly, an adaptive radiance model is applied based on spectral unmixing analysis of. TIR radiance data at TOA (top of atmosphere) collected by MODIS daily 1-km and Landsat - TIRS 16-day sampled at 30-m resolution are used to generate synthetic daily radiance images at TOA at 30-m spatial resolution. The next step consists of unmixing the 30 m (now lower resolution) images using the information about their pixel land-cover composition from co-registered images at higher spatial resolution. In our case study, TIR synthesized data were unmixed to the Sentinel 2 MSI with 10 m resolution. The constrained unmixing preserves all the available radiometric information of the 30 m images and involves the optimization of the number of landcover classes and the size of the moving window for spatial unmixing. Results are still being evaluated, with particular attention for the quality of the data streams required to apply our approach.Optical and Laser Remote Sensin
Hyperfine splitting of [Al VI] 3.66 mu m and the Al isotopic ratio in NGC 6302
No full textThe core of planetary nebula NGC 6302 is filled with high-excitation photoionized gas at low expansion velocities. It represents a unique astrophysical situation in which to search for hyperfine structure (HFS) in coronal emission lines from highly ionized species. HFS is otherwise blended by thermal or velocity broadening. Spectra containing [Al vr] 3.66 mu m P-3(2) <- P-3(1), obtained with Phoenix on Gemini South at resolving powers of up to 75000, resolve the line into five hyperfine components separated by 20-60 km s(-1) as a result of the coupling of the I = 5/2 nuclear spin of Al-27 with the total electronic angular momentum J. The isotope Al-26 has a different nuclear spin of I = 5, and a different HFS, which allows us to place a 3 sigma upper limit on the Al-26/Al-27 abundance ratio of 1/33. We measure the HFS magnetic dipole coupling constants for [Al vr], and provide the first estimates of the electric quadrupole HFS coupling constants obtained through astronomical observations of an atomic transition
Six Years of Bursts with the SPI-ACS
No full textThe anticoincidence system of the INTEGRAL spectrometer has been an essential component of the
interplanetary network since launch. It has observed about 600 events which have been confirmed as
either soft gamma repeaters or cosmic gamma ray bursts by other instruments in the IPN. It has also
observed over 130 events which are unconfirmed, but which are almost certainly weak bursts below the
thresholds of the other IPN experiments. We review the highlights of these observations, which include
gamma-ray bursts, soft gamma repeaters, and one or two extragalactic giant magnetar flares
GLAST burst monitor instrument simulation and modeling
No full textThe GLAST Burst Monitor (GBM) will enhance LAT observations of GRBs by extending the spectral coverage from the LAT threshold down to ∼8keV, and will provide a trigger for re-orienting the spacecraft to observe delayed emission from selected bursts outside the LAT field of view. GBM consists of twelve NaI scintillation detectors operating in the 8 keV to 1 MeV energy range and two BGO scintillation detectors operating in the 150 keV to 30 MeV energy range. Detector resolution, effective area, and angular response have been determined by calibrations. Analyses indicate that the on-board burst threshold will be ∼0.7photonscm-2s-1 and the on-board burst localization accuracy will typically be better than 8°. © 2008 American Institute of Physics
