The proton flare of August 28, 1966 began on H α records at 15 h 21 m 35 s UT. It presented an unusually complex development with flare emission occurring in two distinct plages. The brightest part of the flare attained maximum intensity, 152 % of the continuum, between 15 h 30 m and 15 h 32 m UT. Photometric measurements show that a long-enduring part of the flare continued to decline in intensity until at least 21 h 20 m UT.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43737/1/11207_2004_Article_BF00148084.pd
