1. CDS and SUMER “Companions on SOHO” Dave Pike and Richard Harrison

3. Shared ancestry SOHO study team (inc. PL) - strong spectroscopic requirement GIS - Spectral/temperature coverage NIS – Good spectral/spatial resolution –Feb '85. “NIS could have 7Å bands 500-1300 A. GIS descope or CDS” –Oct '85. “It is generally agreed that lower spatial resolution would be acceptable for the shorter wavelengths.”  CDS & VSP  CDS (NIS/GIS) & SUMER

4. Early planning

5. Performance CDS Large (~100Å), fixed wavelength bands 150 Å  800 Å T ~ 10 4  10 6 K Spectral res. ~500 Spatial res. few arcsec Time res. <1 sec Rigid planning SUMER Smaller (~40Å), variable wavelength bands 500 Å  1600 Å T ~ 10 4  10 6 K Spectral res. ~3 x 10 5 High spatial res. ~1.5" Typically 3 – 10 sec. SCL

6. Solar-B EIS Smaller (~40 Å), fixed wavelength bands 170 Å – 290 Å T ~ 10 5  10 7 K Spectral resolution up to 1.5 x 10 4 Spatial resolution < 2" Time resolution < 1 sec (Launch Aug 2006)

7. CDS/SUMER "best practice" Speak same (spectroscopic) language, if at times with slightly different scientific accents Design driven by science requirements Blue and red books Early joint meetings for collaborative science and including calibration issues, ops modes, slit alignment etc. Creation and formalisation of JOPs Not only an example within SOHO, but carried forward to future projects

8. Calibration Cleanliness  calibration  long-term and inter- comparison science studies Joint work with PTB, rocket under-flights, intercalibration JOPs Generous out-gassing period. Nov 1983 - Philippe talks of cleanliness: “LiF and MgF 2 have known problems of deterioration under 1 solar flux – due to ionised contaminants?”

9. Scientific collaboration 1989-2004 ADS abstracts…. 293 papers ‘CDS+SOHO’ 351 papers ‘SUMER+SOHO’ 114 papers ‘CDS+SUMER’

10. Solar-B Three instruments – spectrometer = EIS EIS calibration, cleanliness program strongly influenced by CDS/SUMER SOHO experience Planning will be a CDS clone Solar-B operations based upon SOHO model Joint team discussions/plans taking place.

11. Solar-B EIS calibration spectrum

12. And finally, a message from… The CDS and SUMER teams have worked closely together since the earliest stages of the SOHO proposal writing. Indeed, Philippe worked alongside Bruce Patchett in the definition of the mission. At one point, we even discussed the possibility of providing a single instrument. However, we decided on two spectrometers, designed to work closely together, to complement each other, and, as far as scientific output is concerned, the CDS and SUMER efforts have been a spectacular success for SOHO. The success comes down to the foresight and skill of a few individuals, such as Philippe. It has been a pleasure to work with Philippe throughout the whole SOHO era. He is a scientist who has never lost sight of the true scientific drivers behind the spectrometers and has inspired many to exploit the mission as fully as possible. Although most of the CDS team at RAL are not able to enjoy the events of 18 November at IAS, we send Philippe our best wishes, our thanks for everything, and hope that he has a long and enjoyable retirement. All the best, Richard Harrison Jim Lang Andrzej Fludra Dave Pike Peter Young Jeff Payne and all the rest of the CDS/Solar Group at RAL