Physical constraints of (612911) 2004 XR190 from a stellar occultation and photometric observations
Session 9.03 Occultations (Targeted)
Thursday 06-27 | 09:50 - 10:10

The TNO 2004 XR190 was discovered on December  11,  2004, from observations within the Canada-France Ecliptic Plane Survey (CFEPS) carried out at the Canada-France-Hawaii Telescope on Mauna Kea, Hawaii. It has a semi-major axis of 57.65 au, a high orbital inclination of 46.54, and an orbital eccentricity of 0.1. Although not the most inclined known TNO, this object's orbit is unique, having a unusual combination of high orbital inclination and low eccentricity, which motivated new dynamical studies involving resonance trapping with Neptune and escaping mechanisms (Gomes 2011; Brasil et al. 2014). Assuming different albedo values, its diameter was estimated from the discovery images to be between 335 and 850 km (Allen et al. 2006; Schaller and Brown 2007). An upper limit of 0.026 mag for the rotational light curve amplitude was obtained from the K2 mission from the Kepler Space Observatory (Kecskeméthy et al. 2022). Despite the inaccurate ephemeris of this faint TNO, we predicted and detected a stellar occultation on January 22, 2021, from one station in the United States of America and another one in Spain. Preliminary results indicate that the object's equivalent diameter is in the order of 600 km. Motivated by this positive detection, we obtained ten nights at the SOAR 4-meter telescope in Chile to perform photometric observations in December 2021, January 2022, and December 2023. This work presents the combined analysis of the stellar occultation and photometric data, constraining the object's fundamental physical parameters such as rotation period, diameter, and albedo.

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