1. Two years of solar observation with PROBA2/LYRA: An overview I. E. Dammasch, M. Dominique, M. Kretzschmar (ROB/SIDC), XII th Hvar Astrophysical Colloquium Hvar, Croatia, 03-07 Sep 2012 LYRA the Large-Yield Radiometer onboard PROBA2

2. Contents  Introduction What is PROBA2 ? What is LYRA ? What data products are delivered ?  Results (selected examples) Quasi-periodic pulsations in flares Lyman-alpha signatures of flares Degradation, and what to do about it Long-term irradiance development Thermal evolution of flares

3. PROBA2  ESA’s “PRoject for On-Board Autonomy”  Belgian microsatellite in Sun-synchronous orbit  725 km altitude  Launched 02 Nov 2009  Nominal operations since March 2010  Technology and science mission  4 innovative instruments and 17 technological experiments for in-orbit demonstration  Among them the EUV imager SWAP and the radiometer LYRA

4. LYRA  Large-Yield RAdiometer  3 instrument units (redundancy)  4 spectral channels per head  3 types of detectors,  Silicon + 2 types of  diamond detectors (MSM, PIN):  - radiation resistant  - insensitive to visible light  compared to Si detectors  High cadence up to 100 Hz

5. Royal Observatory of Belgium (Brussels, B) Principal Investigator, overall design, onboard software specification, science operations PMOD/WRC (Davos, CH) Lead Co-Investigator, overall design and manufacturing Centre Spatial de Liège (B) Lead institute, project management, filters IMOMEC (Hasselt, B) Diamond detectors Max-Planck-Institut für Sonnensystemforschung (Lindau, D) calibration science Co-Is: BISA (Brussels, B), LPC2E (Orléans, F)… LYRA design

6. LYRA filter-detector combinations  Spectral channels covering a wide emission temperature range  Redundancy with different types of detectors  Rad-hard, solar-blind diamond UV sensors (PIN and MSM)  AXUV Si photodiodes  2 calibration LEDs per detector (λ = 465 nm and 390 nm)  Quasi-continuous acquisition during mission lifetime Ly (120-123nm) Hz (190-222nm) Al (17-80nm + <5nm) Zr (6-20nm + <2nm) Unit1 (spare)MSMPINMSMSi Unit2 (nominal)MSMPINMSM Unit3 (campaigns)SiPINSi

7. SWAP and LYRA spectral intervals for solar flares, space weather, and aeronomy LYRA channel 1: the H I 121.6 nm Lyman-alpha line (120-123 nm) LYRA channel 2: the 200-220 nm Herzberg continuum range (now 190-222 nm) LYRA channel 3: the 17-80 nm Aluminium filter range incl the He II 30.4 nm line (+ <5nm X-ray) LYRA channel 4: the 6-20 nm Zirconium filter range with highest solar variablility (+ <2nm X-ray) SWAP: the range around 17.4 nm including coronal lines like Fe IX and Fe X

8. LYRA spectral response

9. LYRA data products  Daily FITS file (uncalibrated, full resolution): “Lev1”  Daily FITS file (calibrated, full resolution): “Lev2”  Daily FITS file (calibrated, 1-minute averages): “Lev3”  Daily overview graphic  Daily flare list  Daily GOES proxy  3-day overview graphic  Monthly overview graphic  SSA service (“Space Situational Awareness”, with SWAP)  … all updated several times per day, after downlink http://proba2.sidc.be

10. LYRA data products: Monthly overview

11. LYRA data products: Flare List LYRA data products: Flare list

12. Example X2.2 flare 15 Feb 2011 01:56 UTC

13. Results (1) L. Dolla et al.: “Time delays in quasi-periodic pulsations observed during the X2.2 solar flare on 2011 February 15” Astrophysical Journal Letters 749:L16 (2012)  QPP observed simultaneously in several wavebands  Focus on fluctuations on timescale 1-30 s  Different time lags between different wavebands  During impulsive phase approx 9 s between first and last (RHESSI, Nobeyama, SDO/ESP, LYRA, GOES)  Possible emission mechanisms discussed

15. LYRA data products: Daily list. Flare list

16. Results (2) M. Kretzschmar et al.: “Sun-as-a-star observation of flares in Lyman-alpha by the PROBA2/LYRA radiometer” Solar Physics (subm.)  Flare signatures in H I 121.5nm  9 in early phase (before degradation), 2 later (spare unit campaign)  Flux increases approx 0.6%  Profile peak compared in different wavelengths (PROBA2, GOES, SOHO/SEM, Suzaku, Kanzelhoehe, GONG)

18. LYRA degradation Temporal response loss of (nominal) unit 2, and estimation of future trends

19. Results (3) A. BenMoussa et al.: “Lessons learned from on-orbit degradation of solar instruments” (in prep)  ROB workshop to start discussion about degradation  Sun-observing instruments exposed to space environment  Examples from SOHO, Hinode, STEREO, ISS, PROBA2, SDO, PICARD  Recommendations to reduce or correct degradation, for future and ongoing missions  Cleanliness control, calibration stability, redundancy concepts, necessary technical developments

20. Comparison of the first 375 hours of LYRA unit 2 and unit 3 Quasi-continuous 06 Jan 2010 – 05 Feb 2010 Campaigns 06 Jan 2010 – 15 Mar 2012

21. Spectral degradation Normalized instrument response loss as experienced by LYRA (2010/11) and SOVA (1992/93) after 200 days of open covers, vs. spectral ranges of their individual channels

22. LYRA data products: Long-term irradiance Development of daily minimum, i.e. without flares, Sep 2011 – Aug 2012

23. Results (4) M. Kretzschmar et al.: “Extreme ultraviolet solar irradiance during the rising phase of solar cycle 24 observed by PROBA2/LYRA” Journal of Space Weather an Space Climate 2, A14 (2012)  LYRA channels 3 (Al) and 4 (Zr) in good agreement with TIMED/SEE and SDO/EVE  Channel 3 with reduced variability due to degradation above 19nm, which can be corrected  Channel 3 (corrected) and channel 4 irradiance increased approx. by a factor 2 between Feb 2010 and Nov 2011

24. LYRA data products: GOES vs. LYRA proxies

25. Results (5) “Thermal evolution of flares”  Using LYRA and GOES curves, flare profiles can be separated into components  These components correspond to different temperature domains  They can be compared to SDO/EVE spectral data  Shapes look similar, radiometric calibration still TBD  Consequences for Earth atmosphere ?  Consequences for instrument design ?

26. Flare components ch2-3 = SXR+EUV “SXR”: emission with log(T)>7 “EUV residual”: emission with 6<log(T)<7 “little bump”: emission with log(T)<6 Compare with SDO/EVE:

27. Thermal evolution plot based on: solar spectra observed by SDO/EVE contribution functions from the CHIANTI atomic database (Chamberlin, Milligan & Woods, Solar Physics 279, 23-42, 2012)

28. M6.7 thermal evolution with LYRA unit 3 Unit 3 has degraded less than unit 2 Slightly different residuals for Al and Zr channels “Cool” component peaks 6 or 5 minutes later than “hot” component

29. LYRA-GOES vs. SDO/EVE (M6.7) Again, corresponding temporal structures can be observed at various temperature levels.

30. Thank you for your attention !  Each year SWAP and LYRA offer a “Guest Investigator Program”  More info, a PROBA2 publication list, and all data products can be found here: http://proba2.sidc.be

31. Example: M1.1 flare, 28 Feb 2011  start to rise at same time  parallel in impulsive phase  GOES peaks earlier  LYRA decreases slower  linear factor in pure flare  irradiance

32. Lyman-alpha signal LYRA in early 2010 signal peaks in rising phase log(T)<6

33. 0.03 MK 0.7 MK 1.4 MK 3.7 MK 7.7 MK SOHO/SUMER

34. Problem: LYRA degradation nominal unit 2 (days), spare unit 3 (hours)

35. Spectral degradation after 200 days in space Experience from SOVA (1992/93) and LYRA (2010/11) combined (“molecular contamination on the first optical surface … caused by UV-induced polymerization”)

36. C8.7 thermal evolution with LYRA unit 2 Unit 2 has degraded more than unit 3 Identical residuals for Al and Zr channels “Cool” component peaks 19 minutes later than “hot” component

37. Reminder: LYRA spectral response channel 2-3: Aluminium filter, nominally 17-80nm channel 2-4: Zirconium filter, nominally 6-20nm pre-launch calibration at BESSY additional SXR components <5 nm, <2 nm for comparison: GOES 0.1-0.8 nm

38. C8.7 thermal evolution with LYRA unit 3 Unit 3 has degraded less than unit 2 Slightly different residuals for Al and Zr channels “Cool” component peaks 22 or 19 minutes later than “hot” component

39. LYRA-GOES vs. SDO/EVE (C8.7) Corresponding temporal structures can be observed at various temperature levels..

40. M6.7 thermal evolution with LYRA unit 2 Unit 2 has degraded more than unit 3 Identical residuals for Al and Zr channels “Cool” component peaks 5 minutes later than “hot” component

41. Conclusions Not the right person to tell you what this means as consequences for the thermosphere, the ionosphere, the geosphere. Eventually, LYRA and GOES together may be able to tell you something about the thermal evolution of flares… … with high temporal resolution, and without being full-blown spectrographs. Or, for future missions: How to get max information with min suitable components? Of course, we are still working on the radiometric calibration, together with our colleagues from SDO/EVE. So far, the shapes look similar, but we still have to attach the correct mW/m² to the curves. See you next time around