IRAS, IUE, and ground-based optical, NIR, mm and submm, and radio observations obtained mainly on Apr. 9-23, 1983, are reported for 19 active extragalactic sources and eight control sources. The ...overall spectra of the compact active sources are shown to be well represented by continuous-curvature functions such as parabolas. The spectra are found to be consistent with models involving continuous particle injection (with synchrotron losses) or first-order Fermi acceleration (with escape and synchrotron losses), but not with models using relativistic Maxwellian electron distributions.
The absolute calibration and characterization of the Multiband Imaging Photometer forSpitzer(MIPS) 70 μm coarse‐ and fine‐scale imaging modes are presented based on over 2.5 yr of observations. ...Accurate photometry (especially for faint sources) requires two simple processing steps beyond the standard data reduction to remove long‐term detector transients. Point‐spread function (PSF) fitting photometry is found to give more accurate flux densities than aperture photometry. Based on the PSF fitting photometry, the calibration factor shows no strong trend with flux density, background, spectral type, exposure time, or time since anneals. The coarse‐scale calibration sample includes observations of stars with flux densities from 22 mJy to 17 Jy, on backgrounds from 4 to 26 MJy sr−1, and with spectral types from B to M. The coarse‐scale calibration is
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackageOT2,OT1{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $702\pm 35$ \end{document}
MJy sr−1MIPS70−1(5% uncertainty) and is based on measurements of 66 stars. The instrumental units of the MIPS 70 μm coarse‐ and fine‐scale imaging modes are called MIPS70 and MIPS70F, respectively. The photometric repeatability is calculated to be 4.5% from two stars measured during every MIPS campaign and includes variations on all timescales probed. The preliminary fine‐scale calibration factor is
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackageOT2,OT1{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $2894\pm 294$ \end{document}
MJy sr−1MIPS70F−1(10% uncertainty) based on 10 stars. The uncertainties in the coarse‐ and fine‐scale calibration factors are dominated by the 4.5% photometric repeatability and the small sample size, respectively. The
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackageOT2,OT1{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $5\,\sigma $ \end{document}
, 500 s sensitivity of the coarse‐scale observations is 6–8 mJy. This work shows that the MIPS 70 μm array produces accurate, well‐calibrated photometry and validates the MIPS 70 μm operating strategy, especially the use of frequent stimulator flashes to track the changing responsivities of the Ge:Ga detectors.
The ratio of the yields of negative to positive pions photoproduced in deuterium has been obtained at six photon energies between 500 and 1000 Mev and at seven angles between 20° and 160° in the ...center of mementum system of the photon and the target nucleon. Pions were selected with a magnetic spectrometer and identified using momentum and specific ionization in a scintillation counter telescope. The spectator model of the deuteron was used to identify the photon energy. The statistical errors assigned to the ratio range between five and fifteen percent.
The results of the present experiment join smoothly with the low energy pi-/pi+ ratios obtained by Sands et al. At high energies the pi-/pi+ ratio varies from 0.4 at forward angles to 2.8 at backwards angles. The cross-sections for pi- photoproduction from neutrons, derived from the pi-/pi+ ratio and the Caltech photoproduction data, are also presented. A peak in the pi- total cross-section occurs at an energy 25-50 Mev below the energy of the second resonace peak in pi+ photoproduction. A phenomenological analysis has been attempted, but no definite conclusions have been reached.
3 Micron Imaging of the Hubble Deep Field Hogg, David W; Neugebauer, Gerry; Cohen, Judith G ...
The Astronomical journal,
04/2000, Letnik:
119, Številka:
4
Journal Article
The Viking infrared thermal mapper measures the thermal emission of the martian surface and atmosphere and the total reflected sunlight. With the high resolution and dense coverage being achieved, ...planetwide thermal structure is apparent at large and small scales. The thermal behavior of the best-observed areas, the landing sites, cannot be explained by simple homogeneous models. The data contain clear indications for the relevance of additional factors such as detailed surface texture and the occurrence of clouds. Areas in the polar night have temperatures distinctly lower than the CO$_{2}$ condensation point at the surface pressure. This observation implies that the annual atmospheric condensation is less than previously assumed and that either thick CO$_{2}$ clouds exist at the 20-kilometer level or that the polar atmosphere is locally enriched by noncondensable gases.
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