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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). 



Required observations:

  • 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?


Required observations:

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.



Required observations:

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.


Required observations:

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


Required observations:

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.