THE ASTRONOMICAL JOURNAL    VOLUME 112, NUMBER 1, PAGE 241            JULY 1996

     SPECTRAL IRRADIANCE CALIBRATION IN THE INFRARED. VI. 3-35 um SPECTRA
                       OF THREE SOUTHERN STANDARD STARS

                                 MARTIN COHEN

 Jamieson Science and Engineering, Inc., Suite 204, 5321 Scotts Valley Drive,
       Scotts Valley, California 95066, and Radio Astronomy Laboratory,
    601 Campbell Hall, University of California, Berkeley, California 94720
                  Electronic mail: cohen@bkyast.berkeley.edu

           FRED C. WITTEBORN, JESSE D. BREGMAN, AND DIANE H. WOODEN

      Space Science Division, Mailstop 245-6, NASA-Ames Research Center,
                        Moffett Field, California 94035
        Electronic mail: (witteborn, bregman, wooden)@ssa1.arc.nasa.gov

                        ALBERTO SALAMA AND LEO METCALFE

         ISO Science Operations Centre, Astrophysics Division of ESA,
                              Villafranca, Spain
            Electronic mail: (asalama, lmetcalf)@iso.vilspa.esa.es


                                   ABSTRACT

    We present three new absolutely calibrated continuous stellar spectra
    from 3 to 35 um, constructed as far as possible from actual observed
    spectral fragments taken from the Kuiper Airborne Observatory (KAO),
    and the IRAS Low Resolution Spectrometer (LRS).  These stars - Alpha1
    Cen, Alpha TrA, and Epsilon Car - augment our previous archive of
    complete absolutely calibrated spectra for northern K and M giants.
    All these spectra have a common calibration pedigree.  The wavelength
    coverage is ideal for calibration of many existing and proposed
    ground-based, airborne, and satellite sensors.  KAO and IRAS data in
    the 15-30 um range suggest that the spectra of cool giants are close to
    Rayleigh-Jeans slopes.  Our observations of Alpha1 Cen, absolutely
    calibrated via our adopted Sirius model, indicate an angular diameter
    in very good agreement with values in the literature, demonstrating
    "closure" of the set of spectra within our absolute framework.  We
    compare our observed Alpha1 Cen spectrum with a published grid of
    theoretical models from Kurucz, and adopt a plausible theoretical
    shape, that fits our spectrum, as a secondary reference spectrum in the
    southern sky.