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HMI Instrument Calibration and Observables

HMI Instrument Calibration and Observables. Conclusion. There is nothing new! Delivered long ago Any questions?. Overview. Calibration Status Image quality Wavelength dependence Polarization Miscellaneous On-Orbit Plans Commissioning Eclipses On-orbit routine Observables Update

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HMI Instrument Calibration and Observables

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  1. HMI Instrument Calibration and Observables

  2. Conclusion • There is nothing new! • Delivered long ago • Any questions?

  3. Overview • Calibration Status • Image quality • Wavelength dependence • Polarization • Miscellaneous • On-Orbit Plans • Commissioning • Eclipses • On-orbit routine • Observables Update • No rotate

  4. Image Quality and Wavelength Dependence • Too complicated for me to figure out • So, what to do?

  5. Image Quality and Wavelength Dependence Delegate!

  6. Polarization – Temperature Dependence Depolaization Front window temperature Front window temperature – leg temperature

  7. Polarization • Commissioning • Some terms (eq. I->(Q,U,V)) can only be determined on-orbit • Zero point for temperature dependence • Routine on-orbit • Not much for polarization. Mainly checks. • Overall Performance • Within spec. • 1% between Q, U, V • Various others

  8. Miscellaneous – LED Ratio

  9. More LED Ratio

  10. Commissioning (Calibration Related) • Much to be done • Check ground results • Eg. Image quality • Get numbers you can’t determine on the ground • Polarization terms • Image oblateness • Determine operating parameters • Which framelist to use • Get involved!

  11. Routine on-orbit • Check for drifts • Focus • Michelson drift • Flatfield • …

  12. Observables • Basic observables in instrument frame • North not necessarily up! • IQUV frame is instrument • Standard observing sequence still TBD! • Decision to be made during commissioning • Get involved!

  13. Framelist Choices Polarization Scheme • Options 1 and 2 – Cameras not combined • Same polarimetric noise per unit time • Option 1 (LCP/RCP on one, Mod A on other) is fast • Some Stokes parameters are made from differences over long time intervals (40-50s) • Significant acceleration effects • Option 2 (LCP/RCP on one, Mod C on other) is slower • But all differences are close in time (4s) • Almost no acceleration effects • Options 3 and 4 – Cameras combined • Depends on ability to combine the cameras • Option 3 (LCP/RCP on one, linear on other) only combines to make Vector • Better polarimetry than 1 and 2 • Calibrations on vector camera does not impact Doppler continuity • Option 4 (Mod A divided on cameras) combines to make both • Even better polarimetry • Also better Doppler • But calibrations interrupt Doppler • Time averaging helps

  14. Conclusion • Calibration looks good • Work still to be done on-orbit • Observables calculation • In good shape • Get involved!

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