UV solar disc imagers of Kuafu-A

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UV solar disc imagers of Kuafu-A

• Pierre Rochus
• Jean-François Hochedez
• Jean-Marc Defise
• Pierre-Alexandre Blanche
• Udo Schuehle

Centre Spatial de Liège, CSL, Belgium SIDC-
ROB, Royal Observatory of Belgium MPS, Lindau,
Germany
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International Telescope Suite for the
Investigation of Solar Eruptive EventsITSISEE
(Its easy! SpW forecast)
ITSISEE is an observatory for Solar Weather
forecast and nowcast
MOSES Multi Order Solar EUV Spectrograph
LyCo Lyman-alpha Coronagraph ViCo Visible light
Coronagraph
EDI (or ELATE?) Euv Lyman-Alpha Telescope
Guide Telescope
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EDI EUV Lyman Alpha Telescopes

• 2 filtergraph telescopes
• FOV gt 45 Arcmin
• Pixel lt 2.6 Arcsec, viz. 1k x 1k or more
• 1 minute non-stop cadence ?!
• More if possible, where/when useful
• 1 Gbit/day per telescope TBC

• 19.5 nm, Fe XII Fe XXIV
• Focal length 1200 mm
• 1 nm FWHM
• Pupil 33 mm diameter

• 121.6 nm, H Ly ?
• Focal length 1200 mm
• Purity gt70, goal 90
• Pupil 50-60 mm TBC

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The EUV Telescope (1/2)

• SoHO-EIT (Jan. 1996) and Proba2-SWAP (Sep. 2007)
  heritage
• CSL ROB in Belgium
• Off-axis Ritchey-Chretien

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The EUV Telescope (2/2)

• Lighter mirrors
• Absence of external baffle
• (There is room for internal baffling)

• Mirrors
• Multi-layer
• super-polished
• Smaller filters (at the entrance pupil)

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Proba2-SWAP (1/2)
A new EUV solar telescope for the ESA PROBA2
mission
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Proba2-SWAP (2/2)

• New technologies
• APS CMOS detector
• Off-axis optical design
• Onboard image processing

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The Lyman-? Telescope

• Quasi-identical optical design as the EUV one
• Heritage from TRC but off-axis
• Transition Region Camera, R. M. Bonnet, 1980
• Multilayer coatings on the 2 mirrors
• Al/MgF2/B4C or Al/MgF2 optimized for 1215 Å.
• gt70 purity (FWHMlt7nm)
• ACTON RESEARCH filters ( solarblind detector?)

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Solar science addressed by the EUV telescope

• 195 (1.6MK) is an established General Purpose
  coronal channel
• Observable in still images
• Coronal Holes (CH are the source of the fast
  wind)
• Active Regions Filaments (AR are flare CME
  sites)
• Sigmoids, EUV flares, post-eruptive arcades
• Observable in image sequences
• Eruption/CME on-disc signatures
• EIT waves dimmings, CME mass estimates
• Filament instabilities leading to their eruption
• Forecasting better
• Progress about physics of event precursors
• Inputs to SpW data assimilation codes

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Solar science addressed by the Ly ? telescope
With ideas from Dr. A. Vourlidas (VAULT PI)

• Ly-a solar images have never been monitored
• Not even by SDO-AIA (which has He II ?
  synergies), Preparation for S.O.
• Brightest line allows fast cadence
• Emission mechanisms (typ. 20 000K but actually
  10-80 000 K)
• Ly-a solar images will reveal (cf VAULT rocket
  experiment)
• dense prominences in absorption and in emission
  (mass estimation)
• CH, jets, spicules (like in H? )
• Cool magnetic field lines over the photosphere at
  the limb (not seen in H? )
• Chromospheric response to Corona and flares,
  moss, Moreton waves
• EUV emission always associated with Ly-a emission
• but not the reverse ? observe inside CH
• Will improve solar irradiance models
• Main energetic contribution to Earth lower
  ionosphere
• Sources of Ly-a irradiance variability
• Imaging give access to irradiance in the
  heliosphere
• ? Planetary aeronomy

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Anticipated improvements of ELATE over SOHO-EIT

• Use of CMOS imaging detector
• 2k x 2k? Solarblind AlGaN CMOS detectors?
• Smart camera schemes, optimal SNR
• Improved calibrations
• Optical element robustness improved
• On-ground, in-flight (UV LEDs)
• Polarimetry at Ly-alpha
• Bommier, V. Sahal-Brechot, S. Leroy, J. L.
• Optimised lossy image or movie compression
  schemes
• 15x and up to 200x ! ? 1 min cadence or better
• Moderate the concern of being at L1 (cf.
  telemetry)
• Data filtering
• Since SOHO, main progress is with CPU and
  algorithmic
• Autonomous operations
• e.g. triggering sub-field high cadence acquisition

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Mission complementarities (1/2)
Timeline Missions complementarities
I UV imaging C Coronagraph R UV Radiometer
06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Soho C IR C IR C IR C IR
Stereo CIS CIS CIS CIS CIS
Solar B I I I
SDO IR IR IR IR IR IR IR IR IR IR
PROBA2 IR IR IR
PROBA3 C C C
KUAFU CIS? CIS? CIS? CIS? CIS?
S.O. CI CI CI CI CI CI
S stereo ability
S stereo ability??
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2 ideas for Kuafu-A

• ITSISEE well tailored for CME forecast but less
  so for flares (often CME-associated)
• Need for a full-sun wide range spectrograph or
  spectro-imager
• Array of 10 one-mirror low-resolution multilayer
  telescopes?
• Spectro-heliograph design (cf. Coronas-F mission)
• Interest for such an instrument exists in Europe
  (B, CH)
• Stereoscopy?
• L1 brings constraints but could bring an
  extremely valuable bonus stereoscopy in
  coordination with the LWS mission SDO (AIA).
• Parallax of possible L1 orbits to be assessed

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Conclusions

• UV solar disc imagers of Kuafu-A (ELATE)
• Rest of the RS suite (ITSISEE)
• Whole scientific payload of the Kuafu mission
• Inescapable for
• solar physics
• Solar Weather monitoring
• in 2012-2017 and beyond