We present a new coalignment method for the EUV Imaging Spectrometer (EIS) on
board the Hinode spacecraft. In addition to the pointing offset and spacecraft
jitter, this method determines the roll angle of the instrument, which has
never been systematically measured, and is therefore usually not corrected. The
optimal pointing for EIS is computed by maximizing the cross-correlations of
the Fe XII 195.119 \r{A} line with images from the 193 \r{A} band of the
Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory
(SDO). By coaligning 3336 rasters with high signal-to-noise ratio, we estimate
the rotation angle between EIS and AIA and explore the distribution of its
values. We report an average value of (-0.387 $\pm$ 0.007)\deg. We also provide
a software implementation of this method that can be used to coalign any EIS
raster.Comment: Accepted for publication in Solar Physics, 11 pages, 7 figure

Auchère, Frédéric

Baker, Deborah

Bocchialini, Karine

Brooks, David H.

Harra, Louise

Mariska, John T.

Pelouze, Gabriel

Warren, Harry P.

English

arXiv

International audienceAbstract Atypical flares cannot be naturally explained with standard models. To predict such flares, we need to define their physical characteristics, in particular, their magnetic environment, and identify pairs of reconnected loops. Here, we present in detail a case study of a confined flare preceded by flux cancellation that leads to the formation of a filament. The slow rise of the noneruptive filament favors the growth and reconnection of overlying loops. The flare is only of C5.0 class but it is a long duration event. The reason is that it is comprised of three successive stages of reconnection. A nonlinear force-free field extrapolation and a magnetic topology analysis allow us to identify the loops involved in the reconnection process and build a reliable scenario for this atypical confined flare. The main result is that a curved magnetic polarity inversion line in active regions is a key ingredient for producing such atypical flares. A comparison with previous extrapolations for typical and atypical confined flares leads us to propose a cartoon for generalizing the concept

Warren, Harry

Brooks, David

Mariska, John

HAL: Hyper Article en Ligne

Comprehensive Determination of the Hinode/EIS Roll Angle

HAL-INSU

We present a new coalignment method for the EUV Imaging Spectrometer (EIS) on board the Hinode spacecraft. In addition to the pointing offset and spacecraft jitter, this method determines the roll angle of the instrument, which has never been systematically measured, and which is therefore usually not corrected. The optimal pointing for EIS is computed by maximizing the cross-correlations of the Fe xii 195.119 Å line with images from the 193 Å band of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). By coaligning 3336 rasters with high signal-to-noise ratio, we estimate the rotation angle between EIS and AIA and explore the distribution of its values. We report an average value of  (-0.387 ± 0.007)^{\circ}. We also provide a software implementation of this method that can be used to coalign any EIS raster

Comprehensive Determination of the Hinode/EIS Roll Angle

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