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  • 1
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    Noise suppression by time exposure oscilloscope photography. (1972)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: We describe a simple and inexpensive means of enhancing repetitive signals obscured by noise with roughly equal amplitude. The signal and noise are displayed on an oscilloscope, and we perform a time average over many traces by time exposure photography. If the oscilloscope triggering is synchronous with the signal, the result is a significant suppression of the offending noise.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 43; May 1972
    Format: text
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  • 2
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    A true gamma-radiation spectrometer. (1968)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Gamma radiation spectrometer using standard scintillation detector and outputs gamma spectrum with spurious peaks and tails corrected
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NUCLEAR SCIENCE SYMPOSIUM; Oct 31, 1967 - Nov 02, 1967; LOS ANGELES, CA|; INESE JOURNAL OF PHY
    Format: text
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  • 3
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    Variability Selected Low-Luminosity Active Galactic Nuclei in the 4 Ms Chandra Deep Field-South (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The 4 Ms Chandra Deep Field-South (CDF-S) and other deep X-ray surveys have been highly effective at selecting active galactic nuclei (AGN). However, cosmologically distant low-luminosity AGN (LLAGN) have remained a challenge to identify due to significant contribution from the host galaxy. We identify long-term X ray variability (approx. month years, observed frame) in 20 of 92 CDF-S galaxies spanning redshifts approx equals 00.8 - 1.02 that do not meet other AGN selection criteria. We show that the observed variability cannot be explained by X-ray binary populations or ultraluminous X-ray sources, so the variability is most likely caused by accretion onto a supermassive black hole. The variable galaxies are not heavily obscured in general, with a stacked effective power-law photon index of Gamma(sub Stack) approx equals 1.93 +/- 0.13, and arc therefore likely LLAGN. The LLAGN tend to lie it factor of approx equal 6-89 below the extrapolated linear variability-luminosity relation measured for luminous AGN. This may he explained by their lower accretion rates. Variability-independent black-hole mass and accretion-rate estimates for variable galaxies show that they sample a significantly different black hole mass-accretion-rate space, with masses a factor of 2.4 lower and accretion rates a factor of 22.5 lower than variable luminous AGNs at the same redshift. We find that an empirical model based on a universal broken power-law power spectral density function, where the break frequency depends on SMBH mass and accretion rate, roughly reproduces the shape, but not the normalization, of the variability-luminosity trends measured for variable galaxies and more luminous AGNs.
    Keywords: Astronomy
    Type: GSFC.JA.6055.2012
    Format: application/pdf
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  • 4
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    Saturn's Atmospheric Composition from Observations by the Cassini/Composite Infrared Spectrometer (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Thermal emission infrared observation of Saturn s atmosphere are being made by the Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft since its insertion in Saturn s orbit on July 2nd, 2004. The measurements made in both limb and nadir modes of observations consist of infrared spectra in the 10-1400/cm region with a variable spectral resolution of 0.53/cm and 2.8/cm, and exhibit rotational and vibrational spectral features that may be analyzed for retrieval of the thermal structure and constituent distribution of Saturn s atmosphere. In this paper, we present a comprehensive analysis of the CIRS infrared observed spectra for retrieval of Saturn s atmospheric composition focusing on the distributions of some selected hydrocarbons, phosphine, ammonia, and possible determination of the isotopic ratios of some species with sufficiently strong isolated spectral features. A comparison of the retrieved constituent distributions with the available data in the literature will be made.
    Keywords: Astronomy
    Type: M10-0339 , 38th COSPAR Scientific Assembly; Jul 18, 2010 - Jul 25, 2010; Bremen, Germany; Germany
    Format: application/pdf
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