9,564 research outputs found
Geologic studies of Yellowstone National Park imagery using an electronic image enhancement system
The image enhancement system is described, as well as the kinds of enhancement attained. Results were obtained from various kinds of remote sensing imagery (mainly black and white multiband, color, color infrared, thermal infrared, and side-looking K-band radar) of parts of Yellowstone National Park. Possible additional fields of application of these techniques are considered
Evaluation of LANDSAT MSS vs TM simulated data for distinguishing hydrothermal alteration
The LANDSAT Follow-On (LFO) data was simulated to demonstrate the mineral exploration capability of this system for segregating different types of hydrothermal alteration and to compare this capability with that of the existing LANDSAT system. Multispectral data were acquired for several test sites with the Bendix 24-channel MSDS scanner. Contrast enhancements, band ratioing, and principal component transformations were used to process the simulated LFO data for analysis. For Red Mountain, Arizona, the LFO data allowed identification of silicified areas, not identifiable with LANDSAT 1 and 2 data. The improved LFO resolution allowed detection of small silicic outcrops and of a narrow silicified dike. For Cuprite - Ralston, Nevada, the LFO spectral bands allowed discrimination of argillic and opalized altered areas; these could not be spectrally discriminated using LANDSAT 1 and 2 data. Addition of data from the 1.3- and 2.2- micrometer regions allowed better discriminations of hydrothermal alteration types
The 3D Structure of N132D in the LMC: A Late-Stage Young Supernova Remnant
We have used the Wide Field Spectrograph (WiFeS) on the 2.3m telescope at
Siding Spring Observatory to map the [O III] 5007{\AA} dynamics of the young
oxygen-rich supernova remnant N132D in the Large Magellanic Cloud. From the
resultant data cube, we have been able to reconstruct the full 3D structure of
the system of [O III] filaments. The majority of the ejecta form a ring of
~12pc in diameter inclined at an angle of 25 degrees to the line of sight. We
conclude that SNR N132D is approaching the end of the reverse shock phase
before entering the fully thermalized Sedov phase of evolution. We speculate
that the ring of oxygen-rich material comes from ejecta in the equatorial plane
of a bipolar explosion, and that the overall shape of the SNR is strongly
influenced by the pre-supernova mass loss from the progenitor star. We find
tantalizing evidence of a polar jet associated with a very fast oxygen-rich
knot, and clear evidence that the central star has interacted with one or more
dense clouds in the surrounding ISM.Comment: Accepted for Publication in Astrophysics & Space Science, 18pp, 8
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EChO Payload electronics architecture and SW design
EChO is a three-modules (VNIR, SWIR, MWIR), highly integrated spectrometer,
covering the wavelength range from 0.55 m, to 11.0 m. The baseline
design includes the goal wavelength extension to 0.4 m while an optional
LWIR module extends the range to the goal wavelength of 16.0 m.
An Instrument Control Unit (ICU) is foreseen as the main electronic subsystem
interfacing the spacecraft and collecting data from all the payload
spectrometers modules. ICU is in charge of two main tasks: the overall payload
control (Instrument Control Function) and the housekeepings and scientific data
digital processing (Data Processing Function), including the lossless
compression prior to store the science data to the Solid State Mass Memory of
the Spacecraft. These two main tasks are accomplished thanks to the Payload On
Board Software (P-OBSW) running on the ICU CPUs.Comment: Experimental Astronomy - EChO Special Issue 201
Proceedings of the Airborne Imaging Spectrometer Data Analysis Workshop
The Airborne Imaging Spectrometer (AIS) Data Analysis Workshop was held at the Jet Propulsion Laboratory on April 8 to 10, 1985. It was attended by 92 people who heard reports on 30 investigations currently under way using AIS data that have been collected over the past two years. Written summaries of 27 of the presentations are in these Proceedings. Many of the results presented at the Workshop are preliminary because most investigators have been working with this fundamentally new type of data for only a relatively short time. Nevertheless, several conclusions can be drawn from the Workshop presentations concerning the value of imaging spectrometry to Earth remote sensing. First, work with AIS has shown that direct identification of minerals through high spectral resolution imaging is a reality for a wide range of materials and geological settings. Second, there are strong indications that high spectral resolution remote sensing will enhance the ability to map vegetation species. There are also good indications that imaging spectrometry will be useful for biochemical studies of vegetation. Finally, there are a number of new data analysis techniques under development which should lead to more efficient and complete information extraction from imaging spectrometer data. The results of the Workshop indicate that as experience is gained with this new class of data, and as new analysis methodologies are developed and applied, the value of imaging spectrometry should increase
A Calibrated Measurement of the Near-IR Continuum Sky Brightness Using Magellan/FIRE
We characterize the near-IR sky background from 308 observations with the
FIRE spectrograph at Magellan. A subset of 105 observations selected to
minimize lunar and thermal effects gives a continuous, median spectrum from
0.83 to 2.5 microns which we present in electronic form. The data are used to
characterize the broadband continuum emission between atmospheric OH features
and correlate its properties with observing conditions such as lunar angle and
time of night. We find that the moon contributes significantly to the
inter-line continuum in the Y and J bands whereas the observed H band continuum
is dominated by the blended Lorentzian wings of multiple OH line profiles even
at R=6000. Lunar effects may be mitigated in Y and J through careful scheduling
of observations, but the most ambitious near-IR programs will benefit from
allocation during dark observing time if those observations are not limited by
read noise. In Y and J our measured continuum exceeds space-based average
estimates of the Zodiacal light, but it is not readily identified with known
terrestrial foregrounds. If further measurements confirm such a fundamental
background, it would impact requirements for OH-suppressed instruments
operating in this regime.Comment: 25 pages, 11 figures, accepted to PAS
Discrimination of rock classes and alteration products in southwestern Saudi Arabia with computer-enhanced LANDSAT data
Digital LANDSAT MSS data for an area in the southwestern Arabian Shield were computer-enhanced to improve discrimination of rock classes, and recognition of gossans associated with massive sulphide deposits. The test area is underlain by metamorphic rocks that are locally intruded by granites; these are partly overlain by sandstones. The test area further includes the Wadi Wassat and Wadi Qatan massive sulphide deposits, which are commonly capped by gossans of ferric oxides, silica, and carbonates. Color patterns and boundaries on contrast-stretched ratio color composite imagery, and on complementary images constructed using principal component and canonical analyses transformations, correspond exceptionally well to 1:100,000 scale field maps. A qualitative visual comparison of information content showed that the ratio enhancement provided the best overall image for identification of rock type and alteration products
Spectroscopic Confirmation of a z=2.79 Multiply Imaged Luminous Infrared Galaxy Behind the Bullet Cluster
We report spectroscopic confirmation and high-resolution infrared imaging of
a z=2.79 triply-imaged galaxy behind the Bullet Cluster. This source, a
Spitzer-selected luminous infrared galaxy (LIRG), is confirmed via polycyclic
aromatic hydrocarbon (PAH) features using the Spitzer Infrared Spectrograph
(IRS) and resolved with HST WFC3 imaging. In this galaxy, which with a stellar
mass of M*=4e9 Msun is one of the two least massive ones studied with IRS at
z>2, we also detect H_2 S(4) and H_2 S(5) pure rotational lines (at 3.1 sigma
and 2.1 sigma) - the first detection of these molecular hydrogen lines in a
high-redshift galaxy. From the molecular hydrogen lines we infer an excitation
temperature T=377+68-84 K. The detection of these lines indicates that the warm
molecular gas mass is 6(+36-4)% of the stellar mass and implies the likely
existence of a substantial reservoir of cold molecular gas in the galaxy.
Future spectral observations at longer wavelengths with facilities like the
Herschel Space Observatory, the Large Millimeter Telescope, and the Atacama
Pathfinder EXperiment (APEX) thus hold the promise of precisely determining the
total molecular gas mass. Given the redshift, and using refined astrometric
positions from the high resolution imaging, we also update the magnification
estimate and derived fundamental physical properties of this system. The
previously published values for total infrared luminosity, star formation rate,
and dust temperature are confirmed modulo the revised magnification; however we
find that PAH emission is roughly a factor of five stronger than would be
predicted by the relations between the total infrared and PAH luminosity
reported for SMGs and starbursts in Pope et al. (2008).Comment: 8 pages, 4 figures, accepted to Ap
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