J.-F. Hochedez, COSPAR ’06, Beijing 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
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. A curtain !. - PowerPoint PPT Presentation
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J.-F. Hochedez, COSPAR ’06, Beijing
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 snake !
A wall !
A curtain !Dr Elephant
J.-F. Hochedez, COSPAR ’06, Beijing
Dimensions of (solar UV) observations
Spatial resolution
Field of ViewCadence
Exposure time
Temporal coverage(Long-term and duty cycle)
Spectral range & resolution +polarimetric diagnostics
Effective area, calibration & signal to noise
J.-F. Hochedez, COSPAR ’06, Beijing
Imagers vs. spectro-radiometers
Radiometer
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
SWAP & LYRA« the High-cadence solar mission »
Image courtesy: Verhaert
• Launch end 2007 (2-year mission)• 60 cm x 70 cm x 85 cm, 120 kg• LEO dawn-dusk orbit• Demonstrate new space technologies
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 wavesEIT image at 19.5 nm every 12 minIrradiance data from SEM
0.1-50 nm and 26-34nm, cadence 5 min
Temporal evolution (2/3)Contribution of solar regions to irradiance variations
last
First image
Last, and rotated
SEM [0.5-50nm]
EIT 19.5 nm (integrated)
Last image
Last image(rotated)
last
First image
Last, and rotated
SEM [0.5-50nm]
EIT 19.5 nm (integrated)
ACTIVE REGION 1 (AR1)
Last image(rotated)
last
First image
Last, and rotated
SEM [0.5-50nm]
EIT 19.5 nm (integrated)
ACTIVE REGION 2 (AR2)
Last image(rotated)
last
First image
Last, and rotated
SEM [0.5-50nm]
EIT 19.5 nm (integrated)
QUIET SUN 1 (QS1)
Last image(rotated)
last
First image
Last, and rotated
SEM [0.5-50nm]
EIT 19.5 nm (integrated)
QUIET SUN 2 (QS2)
Last image(rotated)
SEM 0.1-50 nm
SEM 30.4 nm
AR1
AR2
QS1
QS2 (around AR)
1. Most of the activity associated to AR1
2. AR2 anti-correlated?
3. Some SEM flares not seen in EIT
4. Finer details!
Instrumental pb
SEM 0.1-50 nm
SEM 30.4 nm
AR1
AR2
QS1
QS2 (around AR)
EIT difference images
SEM 0.1-50 nm
SEM 30.4 nm
AR 1
AR 2
QS 1
QS2
Bright front of EIT wave
Flare
.. And dimming
J.-F. Hochedez, COSPAR ’06, Beijing
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
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
Apparent Sun diameter: 25 km
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