The discovery of five quasars at z>4 using the Second Palomar Sky Survey

J. D. Kennefick, R. R. De Carvalho, S. G. Djorgovski, M. M. Wilber, E. S. Dickson, N. Weir, U. Fayyad, J. Roden

    Research output: Contribution to journalArticlepeer-review


    We are conducting a survey to identity z>4 quasars using a digital version of the Second Palomar Sky Survey. The plates are taken in the photographic JFN bands and calibrated to the Gunn-Thuan gri system, making these data suitable for a multicolor search for quasars in the redshift range of 4.0≲z≲4.8. A new software package, SKICAT, was developed to perform automatic reduction of these scans into object catalogs, to classify the objects as stars or galaxies to faint levels objectively using a machine learning decision tree method, and to allow for easy manipulation of the final catalogs. Here we report on the initial results from this survey. We have selected high-redshift quasar candidates from 14 fields with a total area covered of ∼560 deg2 over the magnitude range 16.5≤mr≤19.6. Follow-up work is now well underway, and is complete for several fields. Here we present a preliminary description of the survey as well as spectroscopy, coordinates, and finding charts for our first five z>4 quasars.

    Original languageEnglish (US)
    Pages (from-to)78-86
    Number of pages9
    JournalAstronomical Journal
    Issue number1
    StatePublished - Jul 1995

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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