We just observed the plume of nucleus K with Near-IR camera attached to
188cm telescope at Okayama Astrophysical Observatory,
National Astronomical Observatory of Japan.
Initial flash was detected at 10:25 UT on July 19. This is fainter than Io, and its brightness decreased rapidly. Then the brightness increased again around from 10:31 UT, reached maximum around 10:38 UT. The maximum brightness is roughly 20 times or more of the brightness of Io. Several ND filters were used during the maximum phase in order to keep the signal within the effective range of our detector. These are all in 2.36 micron images.
J. Watanabe, T. Yamashita, H. Hasegawa, S. Takeuchi, M. Abe,
Y. Hirota, E. Nishihara, A. Mori, S. Okumura,