5.1 Additional Science Objectives of EUI
5.1.1 Study the corona and its phenomena in a high spatial and temporal scale (active regions during flares or in quiescent conditions, coronal holes, quiet Sun).
- Whatever the active region target, the high spatial resolution of HRI is used in a mode close to A mode with a time resolution of the order of 1 sec. For the polar coronal hole mode, the high latitude is mandatory and the compression in Lalpha possibly lower than 15 (mode C) . Complementary observations of SPICE in Lbeta would be very useful.
5.1.2 What is the Ly-α emission and absorption in the cool atmosphere (especially in polar coronal holes)? To what extent is it a function of latitude?
The observing mode is C but the observations must be repeated during the various orbits (always at perihelion) in order to cover a large range of latitudes.
Complementary observations of SPICE in Lbeta would be very useful.
5.1.3 Study the coronal He abundance.
The S mode should be OK since there is overlap between METIS FOV and FSI (304). One could modify this mode in three ways : not cropping to 4Rs by 4Rs (in order to increase the FOVs overlap)), decreasing the cadence (down to about an hour) and decreasing the compression by a factor 5.
5.1.4 Reconstruct the solar EUV irradiance (Haberreiter et al., 2014) for all hemispheric directions, in particular for higher latitudes.
Synoptic F174 (and additionally F304) at a cadence of 1/day; high latitude observations are of particular interest; coordniation with other imagers in space, if possible.
5.1.5 Targets of opportunity (planetary quadratures, comets, …).
See also 5.5.1
For Jupiter and Saturn, the most obvious targets are the aurorae (see observations with the Hubble Telescope) to be observed in Lalpha. The visibility will depend on the planet-SO distance. The signal is time variable (from a few kR to MR, Nichols et al. 2007) and detectable (at the typical distance of 4 AU for Jupiter). The disk would cover about 30*30 pixels of HR ILalpha. This assumes an out-of-limb offset pointing … To perform further S/N computations, it is necessary to know the pointing stability.
If one refers to Bennett comet observations (Bertaux, Blamont, Festou 1973) performed at distances smaller than 1 AU, the Lalpha signal should be about 10^^-6 the solar signal with a very large field. This requires out-of-limb offset pointing of HRI Lalpha with perhaps a “reconnaissance” imaging in FSI 30.4 nm. To perform further S/N computations, it is necessary to know the pointing stability. If SO is offset, METIS could observe the extended bubble of the comet in Lalpha.
YZ: Still to define modes and tags.