Model-Based Retrieval of Four Years of JWST/NIRCam Wavefronts

@misc{ray2026modelbased,
  title = {{Model-Based Retrieval of Four Years of JWST/NIRCam Wavefronts}},
  author = {Shrishmoy Ray and Benjamin Pope and Louis Desdoigts and Hayden Greer and Milo Langker and Peter Tuthill and Marshall Perrin and Anand Sivaramakrishnan and Alexandra Greenbaum and Laurent Pueyo and Max Charles},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.40187},
  eprint = {2610.40187},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.40187},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Model-Based Retrieval of Four Years of JWST/NIRCam Wavefronts
AU  - Shrishmoy Ray
AU  - Benjamin Pope
AU  - Louis Desdoigts
AU  - Hayden Greer
AU  - Milo Langker
AU  - Peter Tuthill
AU  - Marshall Perrin
AU  - Anand Sivaramakrishnan
AU  - Alexandra Greenbaum
AU  - Laurent Pueyo
AU  - Max Charles
PY  - 2026
DA  - 2026/10/29
PB  - arXiv
DO  - 10.48550/arxiv.2610.40187
UR  - https://arxiv.org/abs/2610.40187
AB  - The fidelity of data recovered by the James Webb Space Telescope (JWST) depends on precise monitoring of the mirror segments' surfaces and alignment. To this end, every few days the observatory takes pairs of defocused images of a reference star with its NIRCam instrument; a closed-source phase retrieval package is then employed to infer the wavefront. We here present camino (Computational Aberration Modelling and Inference for NIRCam Observations), an open-source algorithm to model NIRCam built in JAX using the differentiable Fresnel optics code dLUX and regularised maximum likelihood inference that has been conditioned on the entire archive of NIRCam wavefront sensing data. We typically improve the reduced chi-squared in fits to the defocused data from 60-65 to 12-13. We reconstruct the wavefront history of JWST from the beginning of science operations to early 2026. This open source implementation operates in parallel to the current STScI phase retrieval algorithm, allowing access by the broader scientific community to high-accuracy wavefront estimation and enabling its direct integration into science-analysis workflows. This represents a major step towards the ultimate goal of predictive calibration methods based on physics-based forward modelling, obviating the need for time-consuming observation of contemporaneous dedicated reference stars.
ER  -