A Short-lived Solar Phenomenon in High Latitude

Abstract

On the morning of June 19, 1947, at 09h. 46m. u.t., while scanning the solar disk with the spectro-helioscope of the Solar Physics Observatory, Cambridge, in Hα, light, my attention was suddenly attracted by an intensely dark absorption flocculus near the south point of the sun. The region had three nuclei of the order of 1′ of arc in diameter or less, more jet black in appearance than any flocculi I have previously observed. There was only just time to confirm the reality of the phenomenon and obtain a preliminary measure of its position before clouds intervened at 09h. 48½m. No sign of the flocculus could be observed at first when the clouds cleared, but at 09h. 57m. one nucleus (A) was picked up at a line-shifter reading corresponding to a velocity of recession of 74 km./sec. Later, the other nuclei, B,B′, were picked up at a still higher velocity as a single marking much fainter in contrast. The complete set of readings in the observing book, together with the corresponding velocities, are given below: