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  • 1
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    A deep x ray survey in the Lockman hole and the soft x ray log N - log S (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The longest pointed observation (152 ksec) with the Rosat position sensitive proportional counter in the direction of the absolutely lowest neutral hydrogen column density is discussed. 26 shallower fields from the Rosat medium sensivity survey are analyzed. 1176 X-ray sources were detected in at least one Rosat energy band in these fields covering a total solid angle of 9.3 deg; 661 of these sources constitute a statistically complete sample detected in the hard band with 0.5 to 2 keV fluxes greater than 2.5 times 10 to the power of minus 15 erg/sq cm s. The faintest limiting flux of the survey is analyzed. Detailed simulations show that confusion effects and other selection biases are relatively small and can be corrected for in the sample. From an analysis in the Lockman field, a best fit slope of approximately 1.8 is found for the extrapolation of the differential X-ray counts below 2.5 times 10 to the power of minus 15 erg/sq cm s. On the basis of this analysis an upper limit of approximately 25% can be found for a truly diffuse background component in the Rosat hard band.
    Keywords: ASTRONOMY
    Type: NASA-CR-194698 , NAS 1.26:194698 , MPE-PREPRINT-238
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  • 2
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    Optical observations of SN 1987D in UGC 7370 (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: This paper presents optical photometry and spectroscopy of SN 1987D, a Type Ia supernova in the nearby galaxy UGC 7370, during the period immediately subsequent to its discovery. The distance modulus of the galaxy, independently determined by the redshift and the Tully-Fisher (1977) relation, is 32.3 + or - 1.0. The maximum brightness of SN 1987D was V about 13.2 and occurred on April 18, 1987, + or - 4 days; the absolute luminosity is about 0.6 mag brighter than the average for SNe Ia. The spectrum of SN 1987D is typical of SNe Ia, but the expansion velocity (9600 km/s) is considerably lower than average.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 99; 1167-117
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  • 3
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    X-ray observations of the bright quasar survey (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Using the Einstein Observatory, X-ray observations of about 80 percent of the quasars in the Bright Quasar Survey located outside the declination range defined by 30 and 60 deg. X-ray emission has been detected above the 3-sigma level for 57 out of 66 quasars observed. This paper describes observations and data reduction and provides a summary of the more detailed analyses and discussion contained in the two accompanying papers (Schmidt and Green 1986, Avni and Tananbaum 1986).
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 305; 57-67
    Format: text
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