Time lapse movies acquired with the Sacramento Peak Observatory 6-in filter coronagraph very infrequently show dramatic transient events. Many of these events (at 1.04 < r/r| < 1.20) are correlated with Ha activity at the hmb, especially with large surges and eruptive prominences. Metric or centrimetric radio bursts are found associated with certain types of 25303 coronal events. The heights to which such disturbances will propagate can often be estimated from the green line movie data. We report the results of a study of all the examples of such transients observed during the last 16 years.
Two classes of coronal expansion phenomena have been studied in Sacramento Peak coronal movies: Slow, slightly decelerated expansion phenomena (v~ 10-~ 2km/sec) and fast, accelerated, quasi-exploding arches (v ~ l0 -> 100 km/sec). The various phenomena were found to be associated with flares in different ways: The slow expansions were long lived post-llare phenomena initiated by the flare; the accelerated expanding arches were either (a) arches expanding prior to and apparently exploding at flare onset, or (b) arches apparently emerging from the flare (probably in its initial phase) and rapidly expanding and exploding, or (c) the expansion and disruption of (originally stable) coronal arches during occurrence of a distant flare. These expansions may be considered as evidence for corresponding flare associated changes in the coronal magnetic field.
A summary is given of the following atmospheric conditions at the Sacramento Peak Observatory: cloud cover, seeing, and précipitable water. Sky brightness observations have been reported in an earlier paper.
A white-light solar flare was visually and photographically observed on May 23, 1967. Maximum white-light phase preceded the Ha intensity maximum, but the event is otherwise similar to earlier reported white-light flares.A large and concentrated region of sunspots of at least three separate groups located approximately 26° N latitude produced chromospheric flares of importance one or larger from May 18 through 29, 1967. On May 23 a series of three separate Ha flares occurred between 1803 and 2156 UT in the largest of these sunspot groups. The second and brightest flare in this sequence is of special interest.
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