1. Coarse phasing JWST using Non- Redundant Tilts (NRT) in TFI a back-up method requiring no extra hardware
Anand Sivaramakrishnan
JWST TFI Science Team (NRM lead)
JAM team lead
Stony Brook University Physics & Astronomy Department
Peter G. Tuthill
University of Sydney & JAM Team
D. Scott Acton
Ball Aerospace
STScI TIPS JIM November
Yesterday morning I awoke to an from Peter Tuthill, a key JAM Team member, telling me he won a senior Australian fellowship, the Futures Fellowship.
This is a big deal for the JAM team. The award will enable him to focus on JWST and space aperture masking, including wavefront sensing, over the next four years.
Peter is responsible for the detailed design of the non-redundant mask in TFI.

2. JWST Commissioning
Exit gate: no segment deviates in piston from the mean piston of all segments by >~ 300nm

3. Baseline method: Dispersed Hartmann Sensing
Well-understood
Works well on WFSC testbed
Two of them in 2 NIRCams
STScI expert Erin Elliott
Looks good
Even with AO remnant speckles are the dominant noise source

4. Why develop back-up? Comfort Uses different instrument than NIRCam SW
Flexible diagnostic tool, mitigate risks
No new hardware required
Look at the NRT idea for show-stoppers
Even with AO remnant speckles are the dominant noise source

5. Image Stacking before Coarse Phasing
segment images must be moved to fall at a common location on one of the NIRCam SCA’s - “Stack Center”
Large moves inaccurate, small moves accurate (details ITAR)

6. Groups of three segments

7. Groups of four segments

8. NRT PSF

9. Spectral Bandwidth

10. Filters Capture range L = lc/b = R.l TFI R=100 4-5um NIRCam LW
R=100 4 filters
2np ambiguity:
3 wavelengths