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Anand Sivaramakrishnan Space Telescope Science Institute Peter Tuthill, Anthony Cheetham

A Back-up Method for Coarse Phasing JWST - Operational Considerations possible with any/all of NIRCam LW, NIRCam SW, NIRISS, MIRI. Anand Sivaramakrishnan Space Telescope Science Institute Peter Tuthill, Anthony Cheetham University of Sydney Scott Acton Ball Aerospace Alexandra Greenbaum

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Anand Sivaramakrishnan Space Telescope Science Institute Peter Tuthill, Anthony Cheetham

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  1. A Back-up Method for Coarse Phasing JWST - Operational Considerationspossible with any/all of NIRCam LW, NIRCam SW, NIRISS, MIRI Anand Sivaramakrishnan Space Telescope Science Institute Peter Tuthill, Anthony Cheetham University of Sydney Scott Acton Ball Aerospace Alexandra Greenbaum Johns Hopkins University Ed Nelan Space Telescope Science Institute

  2. …the big one near the Andromeda, you know the one, they’re almost twins A long time ago in a galaxy far, far away.… Milky Way, Sun, Earth, Hawaii, Keck telescope, 2007…

  3. Mid-Infrared Segment-Tilt `Masking’: 9-segment pattern Peter Tuthill

  4. Mid-Infrared Segment-Tilting: Raw Data CCD Chip Peter Tuthill

  5. 1st Mid-IR Sparse-Aperture results:Rebirth from the Ashes 23% of 1-1.5 Msun have companion with log(P)=4 – 6.5 Total accretion one to a few Mjup (3Mjup) Birth rate = 0.25 x death rate. Therefore MiraAB type systems about as common as YSOs Ireland, Monnier & Tuthill ApJ 2007

  6. Fizeau Interferometric Cophasing of Segmented Mirrorsprecomputed look-up tables from detector data Perfect Piston errors Piston and tilt errors Cheetham, Tuthill, Sivaramakrishnan & Lloyd Optics Express 2012 Three NRT’ed segments

  7. FICSMFizeau Interferometric Cophasing of Segmented Mirrors Segment tilting – choose non-redundant patterns NRT Recover segment piston (few nm) & tip-tilt (10mas) Capture range >150 micron pistons, 0.5 arcsec tilts (NIRCam LW) Should work on NIRISS/NIRCamLW/NIRCamSW/MIRI Cheetham, Tuthill, Sivaramakrishnan & Lloyd Optics Express 2012

  8. JWST Commissioning DHS – coarse phasing baseline FICSM – coarse phasing backup Exit gate: no segment deviates in piston from PM segments’ mean by > 150nm

  9. PSFS during commissioning? a b c d e f Contos et al. 2006 SPIE

  10. Image Stacking process Ball Testbed Telescope data Baseline: move all segments to a single STACK CENTER Large moves inaccurate small moves accurate Must guide during this process Acton et al. 2006 SPIE

  11. Image Stacking before Coarse Phasing • segment images moved to fall at a common location on one detector - “Stack Center” • Large moves inaccurate, small moves accurate • Not ITAR-restricted information

  12. Optics Express 2012 FICSM

  13. Coarse Phasing with Non-Redundant Tilts and FICSM Instead of stacking all segments at same location, separate them into NRT’ed sets, use FICSM on them to phase them (images in 3 filters yield pistons + tilts) 3 applications of FICSM to sets of NRT’ed segments If you want details…

  14. Keck – 36 segments, atmospheric blur determines separation of NRT sets on detector (few to several arcsec) JWST – 18 segments, l/segmentDia determines separation of NRT sets on detector (½ - 1 arcsec) A scaled down Keck-type segment tilting approach works well for JWST Shorter baselines mitigate against higher vibration during JWST commissioning Seed segments and first guiding segments on backplane (not wings) JWST-STScI-002527 on NRT (Sivaramakrishnan & Acton) Tests at Ball Testbed Telescope planned (Acton, Greenbaum, Sivaramakrshnan, Cheetham, Tuthill)

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