Filtering Interpolators for Image Comparison Algorithms

Comparing two or more images, either by differencing or ratioing, is important to many remote sensing problems. Because the pixel sample points for the images are (almost) always separated by some nonzero shift, a resampling, or interpolation, process must be performed if one image is to be accurately compared to another. Considered in Fourier space, an interpolator acts as a filter that attenuates some frequencies (usually high) of the image. Thus, when the shifted and unshifted images are compared, the former has been filtered, while the latter has not; the effect of this difference is called interpolation error. The key idea of this paper is to apply a filter to the unshifted image that matches the filtering effect of applying the interpolator to the shifted image, thereby drastically reducing interpolation error. The resulting interpolators, called filtering interpolators, are derived and discussed in detail elsewhere. Basic results will be given in this presentation

New Constraints on the Energetics, Progenitor Mass, and Age of the Supernova Remnant G292.0+1.8 Containing PSR J1124-5916

We present spatially resolved spectroscopy of the supernova remnant (SNR) G292.0+1.8 with the Chandra X-ray observatory. This SNR contains the 135 ms pulsar, J1124-5916. We apply non-equilibrium ionization (NEI) models to the data. By comparing the derived abundances with those predicted from nucleosynthesis models, we estimate a progenitor mass of 30-40 solar masses. We also derive the intrinsic parameters of the supernova explosion such as its energy, the age of the SNR, the blast wave velocity, and the swept-up mass. In the Sedov interpretation, our estimated SNR age of 2,600 years is close to the pulsar's characteristic age of 2,900 years. This confirms the pulsar/SNR association and relaxes the need for the pulsar to have a non-canonical value for the braking index, a large period at birth or a large transverse velocity. We discuss the properties of the pulsar wind nebula (PWN) in the light of the Kennel and Coroniti model and estimate the pulsar wind magnetization parameter. We also report the first evidence for steepening of the power law spectral index with increasing radius from the pulsar.Comment: 5 pages, 3 figures. To appear in ApJL, Feb 1 2003 (submitted Oct 9 2002, accepted Dec 19 2002

Precision and accuracy of the orbital parameters derived from 2D & 1D space observations of visual or astrometric binaries

Recent investigations (e.g. Han et al. 2001) have shown that fitting the Hipparcos observations with an orbital model when the astrometric wobble caused by the companion is below the noise level can have rather unexpected consequences. With new astrometric missions coming out within the next ten years, it is worth investigating the orbit reconstruction capabilities of such instruments at low signal-to-noise ratio. This is especially important because some of them will have no input catalogue thus meaning that all the orbital parameters will have to be derived from scratch. The puzzling case of almost parabolic orbits is also investigated.Comment: 6 pages, 7 figures, accepted by A&

X-ray Observation and Analysis of The Composite Supernova Remnant G327.1-1.1

Based on the data from the observation of the SNR G327.1-1.1 by ASCA and ROSAT, we find that G327.1-1.1 is a composite remnant with both a nonthermal emission component and a diffuse thermal emission component. The nonthermal component is well fitted by a power-law model with photon index about 2.2. This component is attributed to the emission from the synchrotron nebula powered by an undiscovered central pulsar. The thermal component has a temperature of about 0.4 keV. We attribute it to the emission from the shock-heat swept-up ISM. Its age, explosion energy and density of ambient medium are derived from the observed thermal component. Some charactistics about the synchrotron nebula are also derived. We search for the pulsed signal, but has not found it. The soft X-ray(0.4 - 2 keV) and hard X-ray(2 - 10 keV) images are different, but they both elongate in the SE-NW direction. And this X-ray SE-NW elongation is in positional coincidence with the radio ridge in MOST 843MHz radio map. We present a possibility that the X-ray nonthermal emission mainly come from the trail produced by a quickly moving undiscoverd pulsar, and the long radio ridge is formed when the pulsar is moving out of the boundary of the plerionic structure.Comment: 20 pages, 4 Postscript figures, aasms4.sty and psfig.sty, to be published in Astrophysical Journal, January 20, 1999, Vol. 51

Climate Suite Study for the National Polar-Orbiting Operational Environmental Satellite System Internal Concepts Study

Our recommendations to NPOESS for the sensors it should adopt to meet threshold requirements for global monitoring of ozone and, to some extent, of aerosols and of atmospheric temperature, pressure, and water vapor content are summarized in this report. The degree to which these sensors fulfill other NPOESS requirements than ozone is also summarized. The number of sensors that should be in the constellation is discussed in terms of desired reliability, continuity of coverage, and the ability to cross-calibrate successive sensors. Our recommendations for specific ozone measurement requirements, IORD item 4.1.6.2.28, are given. We make the case that the monitoring of three minor constituents in the upper atmosphere (N20, ClO or ClONO2, and HNO3) should be added to the list of NPOESS requirements because of their importance to long-term ozone studies and the small additional cost required (ozone sensors are already designed to measure them). Specific measurement requirements, which should be regarded as supplementary to the ozone requirement, are given here. The necessity of using two types of sensors, nadir-viewers and limb-scanners, for atmospheric studies is discussed

Resolving the compact HII regions in N160A with HST

Using high-resolution imaging with the Hubble Space Telescope, we study the Large Magellanic Cloud HII region N160A and uncover several striking features of this complex massive star-forming site. The two compact high excitation HII blobs (HEBs) A1 and A2 are for the first time resolved and their stellar content and morphology is revealed. A1, being of higher excitation, is powered by a single massive star whose strong wind has created a surrounding bubble. A2 harbors several exciting stars enshrouded inside large quantities of dust. The whole N160A nebula is energized by three star clusters for which we obtain photometry and study their color-magnitude diagram. The HII region is particularly dusty, with extinction values reaching an A_v~2.5 mag in the visible, and it is separated from the molecular cloud by an outstanding ionization front. A previously detected infrared young stellar object is also accurately located with respect to the HII region.Comment: 11 pages, 5 figures. Accepted for publication in Astronomy & Astrophysics. A version of the paper with higher quality images is available at http://wwwusr.obspm.fr/~heydari/projects/N16

Lung Cancer Metastasis Presenting as a Solitary Skull Mass

Lung cancer has been well documented to spread to bone and the axial skeleton after metastasis to adjacent organs. Bony metastasis is not, however, the typical presenting manifestation. The differential diagnosis for a tissue mass on the skull should warrant a workup for metastatic disease. Bony metastasis plays an important role in treatment and disease management. We report an exceptionally rare case of stage IV lung adenocarcinoma that presented with a solitary skull metastasis and a significant soft-tissue component. The lesion was treated by excision via craniotomy and subsequent medical management of the adenocarcinoma. This case illustrates a very rare presentation of lung adenocarcinoma and also represents what the authors believe to be the first report of a solitary skull mass originating from a lung primary. We also present a review of the literature surrounding bony metastasis to the skull and implications for patient care