Determine the true obliquity of observed near-Earth asteroids

Determine the true obliquity angle of each observed near-Earth asteroid in order to replace the statistically assumed amplitude–phase correction with an object-specific correction and obtain a reliable lower limit on its axis ratio.

Background

The paper corrects observed lightcurve amplitudes to opposition using an empirical amplitude–phase relationship. Because the correction coefficient depends primarily on obliquity, the authors adopt an average obliquity of 60 degrees and use the corresponding mean coefficient for all targets.

The resulting axis-ratio estimates are therefore statistical rather than object-specific. The unresolved issue is the actual obliquity of each asteroid, which is needed to determine its true opposition amplitude and improve the inferred shape constraints.

References

Of course, this value must be taken with caution, as we do not know the true obliquity angle; it is valid only in a statistical sense.

— Photometric characterization of near-Earth asteroids: rotation, taxonomy, and candidate evidence for internal cohesion  (2609.02563 - Carbognani et al., 2 Sep 2026) in Section 2.4, subsection “Dimension and shape estimate”