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IOP Publishing, The Planetary Science Journal, 2(5), p. 35, 2024

DOI: 10.3847/psj/ad0e74

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Photometry of the Didymos System across the DART Impact Apparition

Journal article published in 2024 by Nicholas Moskovitz ORCID, Cristina Thomas ORCID, Petr Pravec ORCID, Tim Lister ORCID, Tom Polakis, David Osip ORCID, Theodore Kareta ORCID, Agata Rożek ORCID, Steven R. Chesley ORCID, Shantanu P. Naidu ORCID, Peter Scheirich ORCID, William Ryan, Eileen Ryan, Brian Skiff ORCID, Colin Snodgrass ORCID and other authors.
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Data provided by SHERPA/RoMEO

Abstract

Abstract On 2022 September 26, the Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the satellite of binary near-Earth asteroid (65803) Didymos. This demonstrated the efficacy of a kinetic impactor for planetary defense by changing the orbital period of Dimorphos by 33 minutes. Measuring the period change relied heavily on a coordinated campaign of lightcurve photometry designed to detect mutual events (occultations and eclipses) as a direct probe of the satellite’s orbital period. A total of 28 telescopes contributed 224 individual lightcurves during the impact apparition from 2022 July to 2023 February. We focus here on decomposable lightcurves, i.e., those from which mutual events could be extracted. We describe our process of lightcurve decomposition and use that to release the full data set for future analysis. We leverage these data to place constraints on the postimpact evolution of ejecta. The measured depths of mutual events relative to models showed that the ejecta became optically thin within the first ∼1 day after impact and then faded with a decay time of about 25 days. The bulk magnitude of the system showed that ejecta no longer contributed measurable brightness enhancement after about 20 days postimpact. This bulk photometric behavior was not well represented by an HG photometric model. An HG 1 G 2 model did fit the data well across a wide range of phase angles. Lastly, we note the presence of an ejecta tail through at least 2023 March. Its persistence implied ongoing escape of ejecta from the system many months after DART impact.