ABSTRACT LYRA is the solar UV radiometer that will embark in 2006 on-board PROBA-2, a technologically oriented ESA micro-mission. LYRA is designed and manufactured by a Belgian-Swiss-German consortium (ROB, PMOD/WRC, IMOMEC, CSL, MPS & BISA). LYRA will monitor the solar irradiance in four carefully selected UV passbands. The channels have been chosen for their relevance to Solar Physics, Aeronomy, and Space Weather: 1/ Lyman-alpha (121.6 nm), 2/ the nm Herzberg continuum range (interference filters for the two previous passbands), 3/ Aluminium filter EUV channel (17-70 nm) covering He II at 30.4 nm, 4/ Zirconium filter XUV channel (1-20 nm), where solar variability is highest. The radiometric calibration will be traceable to synchrotron source standards (PTB & NIST), and the stability will be monitored by on-board calibration sources (VIS & UV LEDs). LYRA benefits from a new technology of detectors based on diamond. Diamond sensors make the instruments radiation hard and solarblind: with such detectors, the filters used to block the unwanted visible light, and that attenuate the desired UV radiation, are unnecessary. With diamond detectors, the accuracy, the cadence, or an optimal combination of both is improved. LYRA will be an innovative solar monitoring tool for operational space weather nowcasting and research. SWAP (Sun Watcher using APS and image Processing), a solar EUV imaging telescope, will operate on PROBA-2 as well. LYRA demonstrates technologies important for future ESA missions such as e.g. Solar Orbiter. The sensor devices are promising for other applications as well: Earth remote sensing, ozone hole monitoring, EUV lithography, among others. LYRA the L arge Y ield R adiometer onboard the ESA PROBA-2 CONSORTIUM J.-F. Hochedez 1, W. Schmutz 2, M. Nesladek 3a+b, Y. Stockman 4, U. Schühle 5, A. Ben Moussa 1, S. Koller 2, K. Haenen 3b, J.-P Halain 4, D. Berghmans 1, J.-M. Defise 4, D. Gillotay 6, V. Slemzin 7, A. Mitrofanov 7, D. McMullin 8, M. Kretzschmar 9, M. Dominique 1, A. Theissen 1, B. Nicula 1, L. Wauters 1, S. Gissot 1, V. Delouille 1, J.H. Lecat 4, H. Roth 2, E. Rozanov 2, I. Ruedi 2, C. Wehrli 2, R. Van der Linden 1, A. Zhukov 1, F. Clette 1, M. d’Olieslaeger 3a+b, J. Roggen 10, P. Rochus 4 1 Royal Observatory of Belgium, Circular Avenue 3., B-1180 Brussels, Belgium 2 Physikalisch-Meteorologisches Observatorium Davos (PMOD) and World Radiation Center (WRC), Dorfstrasse 33, 7260 Davos Dorf, Switzerland 3a IMOMEC, Wetenschapspark 1, B-3590 Diepenbeek, Belgium 3b Institute for Materials Research, Limburgs Universitair Centrum, Wetenschapspark 1, B-3590 Diepenbeek, Belgium 4 Centre Spatial de Liège - Av. Pré Aily B-4031 Angleur - Belgium 5 Max-Planck-Institut für Sonnensystemforschung MPS - D Katlenburg-Lindau - Germany 6 Belgian Institute for Space Aeronomy, Circular Avenue 3., B-1180 Brussels, Belgium 7 Lebedev Physical Institute, 53 Leninsky Prospect, Moscow, , Russia 8 Naval Research Laboratory, 4555 Overlook Ave., S.W., Washington, DC 20375, USA 9 Istituto Fisica dello Spazio Interplanetario, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100, I Roma, Italy 10 IMEC, Kapeldreef 75, B-3001 Leuven, Belgium 11 Imperial College, London, UK LYRA will : Benefit from innovative UV diamond detectors solar blindness radiation-hardness Benefit from ultraviolet in-flight calibration LEDs Technologically assess detectors, LEDs and filters in-flight stability/robustness Assess UV irradiance radiometers capabilities Take advantage of high-cadence observations : 50 Hz LED A  Peak WL = 370 nm LED B  Peak WL = 465 nm  Material: Aluminum alloy 6082 T6  Surface finish:Black anodized  Envelope:X mm Y 92.5 mm Z mm  Mass:5.0 kg Mission duration: 2 Years, launch in 2006 Orbit: dawn-dust sun synchronous orbit Dimensions: 60 cm x 70 cm x 85 cm, 120 kg Payload: Technological demonstrators + LYRA and SWAP Image: courtesy Verhaert The SPACECRAFT DEVELOPMENT Ti/Pt/Au contacts – diamond MSM structures Ø 5mm SOLARBLIND DIAMOND DETECTORS For the very first time in a space instrument, LYRA is using sensors based on diamond, a wide bandgap material. The LYRA solarblind diamond detectors are designed and fabricated at IMOMEC, Belgium with the collaboration of the National Institute for Materials Science (NIMS), Japan. The single pixel devices are MSM structures and PiN junctions, depending on the LYRA channel. The collaboration between ROB and IMOMEC originates with the BOLD program ( submitted to ESA. LYRA contributes to demonstrating the feasibility of a technology that will be highly beneficial in the context of the Solar Orbiter ESA mission. diamond PiN sensor Images: courtesy IMOMEC The PiN devices exhibits a rejection of circa 5 orders of magnitude between 200 nm and 400 nm. The MSM rejection is around 4 orders. These values are sufficient in amplitude. The wavelength cut-off (220nm) is very appropriate for the Herzberg channel, but too high otherwise. Good rejection of the 200nm range is required from the filters. VUV tests and absolute calibrations were made at the Berlin Electron Storage Ring (BESSY) thanks to a collaboration between MPS and PTB (Physikalisch-Technische Bundesanstalt, Germany). CALIBRATION & RADIOMETRIC MODEL Red (MSM) and Blue (PN) - left axis: Synthesis of May-June ‘04 PTB measurements of LYRA detector response Dashed curves - right axis: Filter transmittances (Herzberg, Ly- , Al and Zr) Shadows - units not shown for clarity: Solar minimum and solar maximum spectra used as references The first table shows the expected currents in the various channels and the second, the ratio of solar minimum and solar maximum signal in the four LYRA passbands, calculated from measured transmittances and responsivities, using solar spectra (plotted as grey shades in the left figure). LYRA measurements will be sensitive to solar activity. A detailed interpretation of LYRA measurements will be achieved after further data simulations with various solar spectra, and after comparison of LYRA data with data of other instruments. A.Solar physics 1.In the LYRA timeline, discriminating all temporal features from noise 2.Identifying the above events in the SWAP data to determine their spatial location and nature (flares but also others) 3.Enhancing the accuracy at which the UV solar spectrum is measured, also in view of long-term monitoring 4.Inverting the observations to produce “best-guess” UV solar spectra 5.Looking for high-cadence chronology of events (typically flares) in the 4 LYRA channels, for their causality, impulsive phase, etc,… B.Aeronomy 1.Atmospheric composition analysis by the occultation technique (O2, O3, N2, etc...) 2.Monitoring of the middle- and high-atmosphere response to solar activity 3.Observation of the Polar Mesospheric Clouds 4.Improvement of the climate-chemistry models C.Space Weather application Automated reporting of flares. Attempt to calibrate the LYRA data according to the C, M, X flare nomenclature originally defined in the X-rays ROB 1 unit = 4 wavelength channels 3 units 12 detectors 24 LEDs … LYRA Images courtesy PMOD WRC IN-FLIGHT CALIBRATION LAMPS: UV LEDs Each of the 3 units comprises 4 channels. Each channel corresponds to a collimator and a detector head (one detector, one filter, two calibration LEDs and a precision aperture). The design of the heads takes into account field of view (opening angles), cleanliness, vibration, and thermal issues. The LYRA optical design by PMOD/WRC stems from the photometers of VIRGO onboard SoHO. Images courtesy PMOD WRC CHANNEL DEFINITION & FILTERS STATUS OPERATIONS 4 channels: Herzberg ( nm), Ly-alpha, Al & Zr baselined – FM filters available Lyman-alpha channel is weak in anticipated signal LYRA filter mount LYRA SCIENCE CONCLUSION CSL STATISTICAL DATA ANALYSIS Relevance to Solar Physics, Aeronomy and Space weather: nm (Herzberg channel) nm (Lyman-  channel) nm (Aluminium EUV channel) 1-20 nm (Zirconium XUV channel) LYRA, UV RADIOMETER The dawn-dusk sun-synchronous orbit is ideal for Sun observation, which will occur most of the time. Regularly, the Si unit and the Redundant Diamond unit will be used simultaneously with the nominal one to check the diamond performances and aging effects. For the same reason, it will also be possible to calibrate the detectors with UV and VIS LED’s. During 80 days per year eclipses of max 18 min will occur allowing to perform occultation analysis. LYRA will produce high cadence data (50 Hz) in 4 UV passbands. To fully exploit the wealth of these data, statistical tools are needed. In particular, it is important to analyze small scale phenomena, and to exploit the multivariate aspect of the time series. Challenges: 1.Stabilization of the variance and denoising : although the noise is expected to be small, it will not be Gaussian. Time series can be subject to photon noise, readout noise, as well as aliasing. The Data-Driven Haar-Fisz transform proposed by Fryzlewicz & Delouille (2005) is able to (approximately) gaussianize a signal under very mild conditions on the noise distribution. Once the variance is stabilized, we can threshold the discrete wavelet coefficients to estimate the underlying signal 2.Extraction of 'events' (even at small scales) with as least arbitrary as possible. Different definitions of event leads to different distributions of duration, energy, waiting time (cfr Buchlin et al, 2005) 3.Multivariate analysis: cross-correlation, alignment (wraping) of the different passband curves (work of J. Bigot, J. Ramsay). Test on GOES data Denoising, Alignment of curves Denoising using discrete Daubechies wavelet and hard thresholding Alignment of GOES long ( nm) and GOES short ( nm) for a same period using landmarks of J. Bigot and wraping fct of J. Ramsay. Véronique Delouille 1, J.-F. Hochedez 1, P. Fryzlewicz 11, A. Ben Moussa 1, M. Dominique 1, A. Theissen 1 EGU Meeting, Vienna, April 2005 (*10 -5 ) (*10 -6 ) Wraping fct that aligns 2 GOES signals Dawn-dusk sun-synchronous orbit