JWST's pointing accuracy, based on actual performance, is covered in this article.

Absolute pointing accuracy

The absolute pointing accuracy of JWST  without a science target acquisition is comfortably within the 1.0 arcsecond radial requirement for all four science instruments. Recent analysis (Sohn 2026, in preparation) shows that the 1-sigma (68%) radial blind-pointing accuracies are roughly 26–37 mas for NIRCam and NIRISS, approximately 45 mas for MIRI, and around 67 mas for NIRSpec.

Pointing repeatability is excellent; independent observations at the same target and same position angle usually result in pointings identical to within 0.10" for all instruments. Multiple sources of uncertainty contribute to the overall pointing accuracy such as locations of science instruments on the focal plane, roll angle of the telescope, and guide star coordinates.

Please note that in rare cases (e.g., crowded fields, high background), the guide star is misidentified, resulting in the telescope guiding on a star that is offset from the commanded location. This can lead to the absolute astrometry of the observed image being offset by 1–2 arcsec, or in some cases larger than that.

Pointing accuracy after target acquisition

Observations requiring better final pointing accuracy than 0.10" (e.g., coronagraphic spot placement, repeatable position for NIRISS aperture masking interferometry [AMI], or single object slitless spectroscopy [SOSS]), will need to use onboard target acquisition. Although each instrument mode uses a different target acquisition process, all modes typically achieve target positions within 5.5 mas (1-σ, radial) for NIR instruments, or 14 mas (1-σ, radial) for MIRI. For NIRCam coronagraphy, the recommended small grid dithers yield excellent coronagraphic contrast. 

Target acquisitions for NIRSpec multi-object spectroscopy are the most challenging, because they derive a roll correction for the observatory's position angle in addition to X, Y position offsets. Although the procedure requires careful attention to implement, pointing accuracy with NIRSpec MSA target acquisition is typically better than 25 mas (1-σ, radial). All modes requiring target acquisition meet or exceed their respective pointing requirements.

References

Sohn, S. T., 2026 (in preparation)
As-measured Pointing Performance of JWST