First View of the Extended Green-Line Emission Corona at Solar Activity Minimum Using the LASCO-C1 Coronagraph on SOHO
by R. Schwenn, B. Inhester, S.P. Plunkett, A. Epple,
B. Podlipnik, D.K. Bedford, M.V. Bout,
G.E. Brueckner, K.P. Dere, C.J. Eyles,
R.A. Howard, M.J. Koomen, C.M. Korendyke,
P.L. Lamy, A. Llebaria, D.J. Michels, J.D. Moses,
N.E. Moulton, S.E. Paswaters, G.M. Simnett,
D.G. Socker, O.C. St. Cyr, S.J. Tappin, and D. Wang
- Movie 1:
18 days evolution of the extended corona at solar activity minimum as observed by the LASCO-C1 coronagraph.
This movie was created from images taken with the LASCO-C1 coronagraph
in the green coronal emission line at 530.0 nm (due to FeXIV ions with
temperatures of about 1.6 MK). The time period covered is February 29, 1996
to March 18, 1996, i.e. about two thirds of a solar rotation close to solar
activity minimum. Each image results from differencing a line center image
and an image taken at the nearby continuum at 530.9 nm. Thus, instrumental
straylight and the coronal continuum emission due to Thomson scattering by
coronal electrons cancel out fairly well. Flatfielding has not been
applied (see text). Most pixel defects due to cosmic ray hits were
eliminated by proper interpolation. The raw images were taken every 1 to
two hours, with some longer gaps randomly distributed. We selected them
such that a regular cadence of 10 images per day resulted (181 total).
Longer data gaps were covered by interpolation of adjacent images.
More information on LASCO can be found at the LASCO Home Page.