Synergies between solar UV radiometry and imaging Matthieu Kretzschmar ° Jean-François Hochedez ° Véronique Delouille ° Vincent Barra * Thierry Dudok de Witte ‘ ° Royal Observatory of Belgium, Brussels * ISIMA, Clermont-Ferrand, France ‘ LPCE, Orléans, France J.-F. Hochedez, COSPAR ’06, Beijing

A metaphor about multi-dimensionality A curtain ! Dr Elephant A snake ! A wall ! J.-F. Hochedez, COSPAR ’06, Beijing

Dimensions of (solar UV) observations Effective area, calibration & signal to noise Cadence Exposure time Field of View Spatial resolution Temporal coverage (Long-term and duty cycle) Spectral range & resolution + polarimetric diagnostics J.-F. Hochedez, COSPAR ’06, Beijing

Imagers vs. spectro-radiometers TIMED-SEE, PROBA2-LYRA… No spatial resolution Spectral resolution! Inflight re-calibrated Full Sun More or less spectral resolution Avoid time gaps Good cadence & SNR EUV Imagers SOHO-EIT, PROBA2-SWAP… Imaging Optical design or rastering Flatfield issues Partial FOV Multilayer passbands Usually not 100% duty cycle Possible polarimetry Photon limited J.-F. Hochedez, COSPAR ’06, Beijing

« the High-cadence solar mission » Launch end 2007 (2-year mission) 60 cm x 70 cm x 85 cm, 120 kg LEO dawn-dusk orbit Demonstrate new space technologies SWAP & LYRA « the High-cadence solar mission » J.-F. Hochedez, COSPAR ’06, Beijing Image courtesy: Verhaert

The solar payload of PROBA2 LYRA VUV, EUV & XUV radiometer PI: JF Hochedez LYRA.oma.be SWAP EUV imager PIs: D Berghmans JM Defise SWAP.oma.be Sun J.-F. Hochedez, COSPAR ’06, Beijing

LYRA highlights 4 channels covering a wide temperature range 200-220 nm Herzberg continuum range Lyman-alpha (121.6 nm) Aluminium filter channel (17-70 nm) incl. He II at 30.4 nm Zirconium filter XUV channel (1-20 nm) (rejects strongly He II) Traceable to radiometric standards Calibration campaigns at PTB Bessy synchrotron In-flight stability Rad-hard, not-cooled, oxide-less diamond UV sensors 2 different LEDs per detector Redundancy (3 units) High cadence (up to 100Hz) Quasi-continuous acquisition during mission lifetime J.-F. Hochedez, COSPAR ’06, Beijing

Dec 2005 tbc J.-F. Hochedez, COSPAR ’06, Beijing April 2006 tbc

One of the 3 LYRA units J.-F. Hochedez, COSPAR ’06, Beijing

SWAP highlights 1 channel at 17.4 nm, 1kx1k CMOS-APS detector Detector and global instrument calibrated at PTB Good cadence 1 min consistent with spatial resolution Quasi-continuous acquisition during mission lifetime Duty cycle limited by telemetry only J.-F. Hochedez, COSPAR ’06, Beijing

PROBA2 SWAP J.-F. Hochedez, COSPAR ’06, Beijing

SWAP TARGETS Dimmings EIT wave Post-eruption arcade Target 1 min image cadence will really resolve in time events like EIT waves. 1 min is what is needed for events propagating at sonic speeds Loop openings Plasmoid lifting Flares Erupting prominences J.-F. Hochedez, COSPAR ’06, Beijing

How can SWAP and LYRA work together? 3,11’’ 1 mn ～10s 17.5 nm 1nm FWHM LYRA None ～50 ms 10 ms [0,20]nm [17,70]nm 121.6 nm [200-220]nm Spatial resolution: Temporal resolution: - Nominal: - Optimal/max: … x 1200 Time 0 mn 1 mn Spectral resolution: Wavelength

Spectral information 1 20 121 200 220 17 70 Wavelength (nm) Can we use the fact that the spectral overlap between the Al & Zr LYRA channels corresponds roughly to the SWAP pass band ? No TBC Can we use the 4 (wide ) LYRA pass bands to model 17.5nm? DEM-like, statistical and/or empirical methods 2 pass bands are optically thick 

Plasma temperatures seen by SWAP and LYRA Zirconium Aluminium SWAP Corona (cold 1MK, and ‘hot’ 10MK) Transition region + Corona. Corona mainly cold LYRA & SWAP spectral coverage are very different  useful to think in term of T° Contribution functions (assuming thermal equilibrium) 104 105 108 106 107 J.-F. Hochedez, COSPAR ’06, Beijing

Preliminary conclusions on combining spectral information Hard to “spectrally” combine LYRA and SWAP But, LYRA Al and Zr include SWAP LYRA-Zr and SWAP observe ~same plasma J.-F. Hochedez, COSPAR ’06, Beijing

Using SWAP to identify the regions that make the irradiance vary Mid-term variation Using SWAP to identify the regions that make the irradiance vary EUV irradiance model track AR, QS, CH Cf. NRLEUV (Warren et al 2001), Kretzschmar et al 2004 If success, whole spectral irradiance variability is modeled hence LYRA time series (at SWAP cadence only) J.-F. Hochedez, COSPAR ’06, Beijing

Using SWAP to identify the regions that make the LYRA irradiances vary Small-term variations Using SWAP to identify the regions that make the LYRA irradiances vary A prospectful new field 4 LYRA pass bands  chronology of solar events in different parts of the solar atmosphere Can we observe irradiance counterparts brightenings, dimmings, others? SEM:0-50 nm J.-F. Hochedez, COSPAR ’06, Beijing

Temporal evolution (1/3) Using radiometers to re-calibrate imagers If roughly the same plasma, one expects similar normalized variations for integrated count rates Cross-calibrations mutually improve long-term stability J.-F. Hochedez, COSPAR ’06, Beijing

Temporal evolution (2/3) Contribution of solar regions to irradiance variations SEM [0.5-50nm] EIT 19.5 nm (integrated) Comparing instruments with different aim(s) and pass bands… e.g. SEM Flares not visible in the integrated EIT flux at 19.5

Temporal evolution (2/3) Contribution of solar regions to irradiance variations Method: Segment regions by hand on 1st image Rotate images so that regions of interest appear always at the same position. Not the best method but fast and quite easy The rotation induces some unwanted effects  Results are indicative & illustrative Data: 1st of April 1997; Several flares and EIT waves EIT image at 19.5 nm every 12 min Irradiance data from SEM 0.1-50 nm and 26-34nm, cadence 5 min

last Last image First image Last, and rotated Last image (rotated) SEM [0.5-50nm] EIT 19.5 nm (integrated) Last image (rotated)

last First image Last, and rotated Last image (rotated) ACTIVE REGION 1 (AR1) Last, and rotated SEM [0.5-50nm] EIT 19.5 nm (integrated) Last image (rotated)

last First image Last, and rotated Last image (rotated) ACTIVE REGION 2 (AR2) Last, and rotated SEM [0.5-50nm] EIT 19.5 nm (integrated) Last image (rotated)

last First image Last, and rotated Last image (rotated) QUIET SUN 1 (QS1) Last, and rotated SEM [0.5-50nm] EIT 19.5 nm (integrated) Last image (rotated)

last First image Last, and rotated Last image (rotated) QUIET SUN 2 (QS2) Last, and rotated SEM [0.5-50nm] EIT 19.5 nm (integrated) Last image (rotated)

Most of the activity associated to AR1 AR2 anti-correlated? SEM 0.1-50 nm SEM 30.4 nm AR1 Most of the activity associated to AR1 AR2 anti-correlated? Some SEM flares not seen in EIT Finer details! AR2 QS1 QS2 (around AR) Instrumental pb

EIT difference images SEM 0.1-50 nm SEM 30.4 nm AR1 AR2 QS1 QS2 (around AR) EIT difference images

Bright front of EIT wave SEM 0.1-50 nm SEM 30.4 nm Flare AR 1 AR 2 Bright front of EIT wave QS 1 QS2 .. And dimming

Temporal evolution (3/3) Imagers can potentially compute irradiance for other heliospheric directions i.e. other planets c.f. Auchère et al 2005 Use hi-cadence radiometer time series to decrease temporal aliasing in image sequences… Having assessed expected variability = f(x,y) J.-F. Hochedez, COSPAR ’06, Beijing

Using LYRA for aeronomy studies Apparent Sun diameter: 25 km PROBA2 has eclipse periods. During occultation, it will see the Sun thru the Earth’s atmosphere This allows LYRA to measure the attenuation of the solar flux from which one can derive atmospheric properties LYRA measurements J.-F. Hochedez, COSPAR ’06, Beijing

Using SWAP for aeronomy studies Independent SWAP occultation observations Cadence limited  Only 17.4nm  Imaging sequence  No need to deconvolve for Sun area No need to assume disc homogeneity SWAP measurements J.-F. Hochedez, COSPAR ’06, Beijing

Conclusion Design new full Sun instruments meant to optimize the spectro-spatio-temporal balance! Spectro-heliograph (such as on CORONAS-F)? Array of >9 “low” spatial resolution multilayer telescopes paving the accessible UV spectrum Smart camera schemes autonomously compromising between cadence and SNR J.-F. Hochedez, COSPAR ’06, Beijing

J.-F. Hochedez, COSPAR ’06, Beijing

Quit complaining about your job! J.-F. Hochedez, COSPAR ’06, Beijing