Browsing by Author "Odewahn, SC"

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    Peculiar broad absorption line quasars found in the digitized palomar observatory sky survey
    (2003) Brunner, RJ; Hall, PB; Djorgovski, SG; Gal, RR; Mahabal, AA; Lopes, PAA; de Carvalho, RR; Odewahn, SC; Castro, S; Thompson, D
    With the recent release of large (i.e., greater than or similar to 100 million objects), well-calibrated photometric surveys, such as Digitized Palomar Observatory Sky Survey (DPOSS), Two Micron All Sky Survey, and Sloan Digital Sky Survey, spectroscopic identification of important targets is no longer a simple issue. In order to enhance the returns from a spectroscopic survey, candidate sources are often preferentially selected to be of interest, such as brown dwarfs or high-redshift quasars. This approach, while useful for targeted projects, risks missing new or unusual species. We have, as a result, taken the alternative path of spectroscopically identifying interesting sources with the sole criterion being that they are in low-density areas of the g-r and r-i color space defined by DPOSS. In this paper, we present three peculiar broad absorption line quasars that were discovered during this spectroscopic survey, demonstrating the efficacy of this approach. PSS J0052+2405 is an iron low-ionization broad absorption line (LoBAL) quasar at a redshift z = 2.4512-0.0001 with very broad absorption from many species. PSS J0141+3334 is a reddened LoBAL quasar at z = 3.005 +/- 0.005 with no obvious emission lines. PSS J1537+1227 is an iron LoBAL at a redshift of z = 1.212 +/- 0.007 with strong narrow Mg II and Fe II emission. Follow-up high-resolution spectroscopy of these three quasars promises to improve our understanding of BAL quasars. The sensitivity of particular parameter spaces, in this case a two-color space, to the redshift of these three sources is dramatic, raising questions about traditional techniques of de. ning quasar populations for statistical analysis.
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    Tests of the accelerating universe with near-infrared observations of a high-redshift type Ia supernova
    (2000) Riess, AG; Filippenko, AV; Liu, MC; Challis, P; Clocchiatti, A; Diercks, A; Garnavich, PM; Hogan, CJ; Jha, S; Kirshner, RP; Leibundgut, B; Phillips, MM; Reiss, D; Schmidt, BP; Schommer, RA; Smith, RC; Spyromilio, J; Stubbs, C; Suntzeff, NB; Tonry, J; Woudt, P; Brunner, RJ; Dey, A; Gal, R; Graham, J; Larkin, J; Odewahn, SC; Oppenheimer, B
    We have measured the rest-frame B-, V-, and I-band light curves of a high-redshift type Ia supernova (SN 1a), SN 1999Q (z = 0.46), using the Hubble Space Telescope (HST) and ground-based near-infrared detectors. A goal of this study is the measurement of the color excess, EB-I, a sensitive indicator of interstellar or intergalactic dust, which could affect recent cosmological measurements from high-redshift SNe Ia. Our observations disfavor a 30% opacity of SN Ia visual light by dust as an alternative to an accelerating universe. This statement applies to both Galactic-type dust (rejected at the 3.4 sigma confidence level) and grayer dust (grain size > 0.1 mu m, rejected at the 2.3-2.6 sigma confidence level) as proposed by Aguirre. The rest-frame I-band light curve shows the secondary maximum 1 month after the B maximum typical of nearby SNe fa of normal luminosity, providing no indication of evolution as a function of redshift out to z approximate to 0.5. An expanded set of similar observations could improve the constraints on any contribution of extragalactic dust to the dimming of high-redshift SNe Ia.