Observation of a metallic prominence on October 15 and 16, 1969.

The paper discusses spectrographic observations of a very bright and complex quiet-time prominence that appeared on the eastern limb of the sun. Some 60 spectrograms of the prominence were obtained in the wavelength region between 3300 and 6600 A along with 23 polarization photographs in the 4227-A Ca I line. A total of 276 spectral lines of various elements are identified, including 63 Fe I lines, 48 Ti II lines, 7 Cr I and 14 Cr II lines, 3 Ca I and 4 Ca II lines, and 13 Ni I lines. Balmer-line profiles are calculated up to H-26, an upper limit of 100 billion per cu cm is placed on the electron density and an electron temperature of 4990 K is estimated. It is shown that the metallic-line emission originated exclusively in a filament which also showed the greatest luminosity in the hydrogen and Ca II K lines.