Apparent Change in Comet 103P/Hartley 2’s Rotation Period During 2023/2024 Measured via Aperture Photometry

Abstract A photometric study of Comet 103P/Hartley 2 is presented, aiming at the detection and analysis of rotationally induced variability during its latest apparition 2023/2024. Brightness measurements within a 5000 km radius aperture using a green filtered spectral range reveal periodic variations, despite the use of different instrumentation, non-standard filters, and varying observing conditions. An increase of the rotation period from 18.6 to 19.1 hr within about 4 months was found, a slowing-down of the rotation similar to results from the apparition in 2010.