Summary of Mount Wilson Magnetic Observations of Sunspots for March and April, 1939

1939 Publications of the Astronomical Society of the Pacific  
When the sun was examined with the spectrohelioscope at 14 h 40 111 G.C.T. on April 25, 1939, a small but rather bright prominence of the sunspot type was observed at the east limb in latitude 21° S. Its appearance was very ordinary, like a single column extending about 30,000 km above the chromosphere, but when Ha was moved off the second slit, the prominence remained visible over a large range in wave length with only slight changes in form. With the second slit wide open and the solar image
more » ... nd the solar image stationary, Ha appeared very broad with large displacements, especially toward the violet (Plate XXIV, a). Similar displacements were observed in the D3 line of helium.
doi:10.1086/125042 fatcat:foo3vqmqjvgjvegpn6ysm73mda