1,2,3,4,7,3,8,5,6,4,4,4,12,- 1LIRA, CNRS UMR-8254, Observatoire de Paris, Meudon, France (damya.souami@obspm.fr)
- 2naXys, University of Namur, 61 rue de Bruxelles, Namur, B-5000, Belgium
- 3LTE, Observatoire de Paris, Paris, France
- 4Instituto de Astrofisica de Andalucia, Granada, Spain
- 5Observatorio Nacional/MCTI, Rio de Janeiro, Brazil
- 6Laboratorio Interinstitucional de e-Astronomia – LIneA, Rio de Janeiro, Brazil
- 7Institut Polytechnique des Sciences Avancees IPSA, France
- 8Federal University of Technology Parana, Curitiba, Brazil
- 9Center of Research in Astronomy, Astrophysics and Geophysics - CRAAG, Algeria
- 10International Occultation Timing Association - European Section, Germany
- 11International Occultation Timing Association, USA
- 12Trans-Tasman Occultation Alliance, New Zealand
- 13Research Center of Astronomy, Francisco J. Duarte (CIDA), Venezuela
The powerful method of stellar occultations is a technique uniquely approaching the performances of planetary space missions. For remote objects such as 2013LU28 stellar occultations are by far the best method we have to determine its size and shape at km-level accuracy, and provide high accuracy astrometry to help better constrain the orbital solution.
(468861) 2013LU28 was discovered on June 8th, 2013 with the Mount Lemmon Survey in Arizona. It is a fascinating and intriguing object from the dynamical standpoint, with a semi-major axis of ∼183.4 AU, an inclination with respect to the ecliptic of ∼ 125°.3, and an eccentricity of ∼ 0.954. It was at its perihelion on June 20th, 2024 at ∼ 8.7AU. It has recently been observed with NIRSpec/JWST in the framework of the DiSCo-TNOs programme as well as MIRI/JWST (no published results as yet).
After chasing occultation opportunities by (468 861) 2013LU28 for about five years, we have only very recently succeeded with three multi-chord occultations recorded.
In this paper, we present the results of three multi-chord occultation campaigns on Jan. 30th (Europe and United States), Feb. 18th (Algeria, Canary Islands, and Venezuela), and March 18th, 2025 (USA) events, which have allowed to improve the astrometry, measure the size of the object and provide valuable constraints on its shape. The data from these occultations were combined with rotational light-curves obtained from Sierra Nevada Observatory, which allow to constrain the phase and have a better assessment of the 3D shape model.
Acknowledgements - This campaign is carried out under the ”Lucky Star” umbrella, an EU-funded research activity that agglomerates the efforts of the Paris, Granada, and Rio teams. (cf. https://lesia.obspm.fr/lucky-star/). Moreover, we would like to Acknowledge the contribution to these three campaigns of the 90+ IOTA members and non IOTA observers who cannot be cited here because of the limitations in the number of characters. The campaigns leads are co-authors to the abstract.
How to cite: Souami, D., Lecacheux, J., LTE, Observatoire de Paris, Paris, France, B., Ortiz, J.-L., Pereira, C. L., Desmars, J., Braga-Ribas, F., Santos-Sanz, P., Kilic, Y., Morales Palomino, N. F., Baba-Aissa, D., Beisker, W., Dunham, D., Gault, D., Guhl, K., Herald, D., Kloes, O., and Navas, G.: Constraining the astrometry, size, and shape of Trans-Neptunian Object (468 861) 2013LU28 from three multi-chord occultation events (01/2025 to 03/2025), EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–12 Sep 2025, EPSC-DPS2025-254, https://doi.org/10.5194/epsc-dps2025-254, 2025.
