UV solar disc imagers of Kuafu-A

1. 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

2. International Telescope Suite for the Investigation of Solar Eruptive EventsITSISEE (It’s easy! … SpW forecast…) ITSISEE is an observatory for Solar Weather forecast and nowcast MOSES Multi Order Solar EUV Spectrograph LyCoLyman-alpha Coronagraph ViCoVisible light Coronagraph EDI (or ELATE?) Euv + Lyman-Alpha Telescope + Guide Telescope J.-F. Hochedez, ROB-SIDC

3. 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: >70%, goal = 90% Pupil 50-60 mm TBC EDI = EUV + Lyman Alpha Telescopes • 2 filtergraph telescopes • FOV > 45 Arcmin • Pixel < 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 J.-F. Hochedez, ROB-SIDC

4. The EUV Telescope (1/2) • SoHO-EIT (Jan. 1996) and Proba2-SWAP (Sep. 2007) heritage • CSL + ROB in Belgium • Off-axis Ritchey-Chretien J.-F. Hochedez, ROB-SIDC

5. Lighter mirrors Absence of external baffle (There is room for internal baffling) Mirrors Multi-layer super-polished Smaller filters (at the entrance pupil) The EUV Telescope (2/2) J.-F. Hochedez, ROB-SIDC

6. Proba2-SWAP (1/2) A new EUV solar telescope for the ESA PROBA2 mission J.-F. Hochedez, ROB-SIDC

7. Proba2-SWAP (2/2) • New technologies: • APS CMOS detector • Off-axis optical design • Onboard image processing J.-F. Hochedez, ROB-SIDC

8. 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. • >70% purity(FWHM<7nm) • ACTON RESEARCH filters (+ solarblind detector?) J.-F. Hochedez, ROB-SIDC

9. 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 J.-F. Hochedez, ROB-SIDC

10. With ideas from Dr. A. Vourlidas (VAULT PI) Solar science addressed by the Ly  telescope • 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 J.-F. Hochedez, ROB-SIDC

11. 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 J.-F. Hochedez, ROB-SIDC

12. Mission complementarities (1/2) Timeline & Missions complementarities I : UV imaging C: Coronagraph R: UV Radiometer S: stereo ability S: stereo ability?? J.-F. Hochedez, ROB-SIDC

13. 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 J.-F. Hochedez, ROB-SIDC

14. 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 J.-F. Hochedez, ROB-SIDC