|
Solar Stereoscopy with STEREO/EUVI A and B spacecraft from small (6°) to large (170°) spacecraft separation angles
|
|
Markus J. Aschwanden Submitted: 2012-07-11 14:11
We performed for the first time stereoscopic triangulation of coronal
loops in active regions over the entire range of spacecraft separation
angles (α sep≈ 6°, 43°, 89°, 127°,
and 170°). The accuracy of stereoscopic correlation depends mostly
on the viewing angle with respect to the solar surface for each
spacecraft,
which affects the stereoscopic correspondence identification of loops in
image pairs. From a simple theoretical model we predict an optimum range
of α sep ≈ 22°-125°, which is also experimentally
confirmed. The best accuracy is generally obtained when an active region
passes the central meridian (viewed from Earth), which yields a
symmetric
view for both STEREO spacecraft and causes minimum horizontal
foreshortening.
For the extended angular range of α sep≈
6°-127° we
find a mean 3D misalignment angle of μPF ≈ 21°-39°
of stereoscopically triangulated loops with magnetic potential field
models,
and μFFF ≈ 15°-21° for a force-free field model,
which is partly caused by stereoscopic uncertainties muSE ≈
9°. We predict optimum conditions for solar stereoscopy during
the time
intervals of 2012-2014, 2016-2017, and 2021-2023.
Authors: Markus J. Aschwanden, Jean-Pierre Wülser, Nariaki Nitta, and James Lemen
Projects: STEREO
|
Publication Status: Solar Physics (in press)
Last Modified: 2012-07-12 09:38
|
 
 
 
 
|
|