JWST-TST Proper Motions: I. High-Precision NIRISS Calibration and Large Magellanic Cloud Kinematics
Abstract
We develop and disseminate effective point-spread functions and geometric-distortion solutions for high-precision astrometry and photometry with the JWST NIRISS instrument. We correct field dependencies and detector effects, and assess the quality and the temporal stability of the calibrations. As a scientific application and validation, we study the proper motion (PM) kinematics of stars in the JWST calibration field near the Large Magellanic Cloud (LMC) center, comparing to a first-epoch Hubble Space Telescope (HST) archival catalog with a 16-yr baseline. For stars with G~20, the median PM uncertainty is ~13 as yr (3.1 km s), better than Gaia DR3 typically achieves for its very best-measured stars. We kinematically detect the known star cluster OGLE-CL LMC 407, measure its absolute PM for the first time, and show how this differs from other LMC populations. The inferred cluster dispersion sets an upper limit of 24 as yr (5.6 km s) on systematic uncertainties. Red-giant-branch stars have a velocity dispersion of 33.8 0.6 km s, while younger blue populations have a narrower velocity distribution, but with a significant kinematical substructure. We discuss how this relates to the larger velocity dispersions inferred from Gaia DR3. These results establish JWST as capable of state-of-the-art astrometry, building on the extensive legacy of HST. This is the first paper in a series by our JWST Telescope Scientist Team (TST), in which we will use Guaranteed Time Observations to study the PM kinematics of various stellar systems in the Local Group.
Keywords
Cite
@article{arxiv.2303.00009,
title = {JWST-TST Proper Motions: I. High-Precision NIRISS Calibration and Large Magellanic Cloud Kinematics},
author = {M. Libralato and A. Bellini and R. P. van der Marel and J. Anderson and S. T. Sohn and L. L. Watkins and L. Alderson and N. Allen and M. Clampin and A. Glidden and J. Goyal and K. Hoch and J. Huang and J. Kammerer and N. K. Lewis and Z. Lin and D. Long and D. Louie and R. J. MacDonald and M. Mountain and M. Peña-Guerrero and M. D. Perrin and L. Pueyo and I. Rebollido and E. Rickman and S. Seager and K. B. Stevenson and J. A. Valenti and D. Valentine and H. R. Wakeford},
journal= {arXiv preprint arXiv:2303.00009},
year = {2023}
}
Comments
28 pages, 25 figures, 2 tables. Accepted for publication in ApJ. The effective point-spread-function models, the geometric-distortion solutions and a preliminary version of the code are available at the links provided in the manuscript