THE ASTRONOMICAL JOURNAL    VOLUME 114, NUMBER 2, PAGE 699        AUGUST 1997

               SPECTROPHOTOMETRY OF 237 STARS IN 7 OPEN CLUSTERS

                       LORI CLAMPITT AND DAVID BURSTEIN

        Department of Physics and Astronomy, Arizona State University,
                           Tempe, Arizona 85287-1504
      Electronic mail: clampitt@accesscom.com, burstein@samuri.la.asu.edu


                                   ABSTRACT

     Spectrophotometry is presented for 237 stars in 7 nearby open
     clusters: Hyades, Pleiades, Alpha Persei, Praesepe, Coma Berenices, IC
     4665, and M39.  The observations were taken by Lee McDonald and David
     Burstein using the Wampler single-channel scanner on the Crossley
     0.9 m telescope at Lick Observatory from 1973 July through 1974
     December. Sixteen bandpasses spanning the spectral range 3500-7780 A
     were observed for each star, with bandwidths 32, 48, or 64 A. Data are
     standardized to the Hayes-Latham system to mutual accuracy of 0.016
     mag per passband. The accuracy of the spectrophotometry is assessed in
     three ways on a star-by-star basis. First, comparisons are made with
     previously published spectrophotometry for 19 stars observed in
     common. Second, (B-V) colors and uvby colors are compared for 236
     stars and 221 stars, respectively. Finally, comparisons are made for
     200 main sequence stars to the spectral synthesis models of Kurucz,
     fixing log g = 4.0 and [Fe/H] = 0.0, and only varying effective
     temperature. The accuracy of tests using uvby colors and the Kurucz
     models are shown to track each other closely, yielding an accuracy
     estimate (1 sigma) of 0.01 mag for the 13 colors formed from
     bandpasses longward of the Balmer jump, and 0.02 mag for the 3 colors
     formed from the three bandpasses below the Balmer jump. In contrast,
     larger scatter is found relative to the previously published
     spectrophotometry of Bohm-Vitense & Johnson (16 stars in common) and
     Gunn & Stryker (3 stars). We also show that the scatter in the fits of
     the spectrophotometric colors and the uvby filter colors is a
     reasonable way to identify the observations of which specific stars
     are accurate to 1 sigma, 2 sigma, .... As such, the residuals from
     both the filter color fits and the Kurucz model fits are tabulated for
     each star where it was possible to make a comparison, so users of
     these data can choose stars according to the accuracy of the data that
     is appropriate to their needs.  The very good agreement between the
     models and these data verifies the accuracy of these data, and also
     verifies the usefulness of the Kurucz models to define
     spectrophotometry for stars in this temperature range (> 5000
     K). These data define accurate spectrophotometry of bright, open
     cluster stars that can be used as a secondary flux calibration for
     CCD-based spectrophotometric surveys. (c) 1997 American Astronomical
     Society.