# # Program information file # PROGRAM_ID 2024B079 PROGRAM_TITLE Stellar occultation events by multiple systems in the trans-neptunian region. PROGRAM_INV1 Flavia Luane Rommel PROGRAM_INV2 Estela Fernandez-valenzuela PROGRAM_INV3 Bryan Holler PROGRAM_INV4 Ben Proudfoot PROGRAM_INV5 Cameron Collyer PROGRAM_SCICAT Centaurs / TNOs / KBOs PROGRAM_ABSTRACT_BEG Trans-Neptunian Objects [TNOs] are thought to be remnants of the protoplanetary disc from which the solar system was formed. Due to their distance from the Sun, they may retain essential information from the primordial solar nebula. A great variety of surface colors, shapes, and sizes have been found in the trans-Neptunian region, including binaries and multiple systems. Binaries, in special, are considered valuable sources of information for improving formation theories, but sizes and orbits are difficult to obtain. Among all observational techniques, stellar occultations can help to determine an object's size with sub-km precision. This time-critical event occurs when an opaque body blocks the stellar flux for a given observer on Earth. In this context, three stellar occultation events by Trans-Neptunian multiple systems have been identified to be observable from Hawaii and IRTF during the 2024B semester: [47171] Lempo on 2025-01-03 UT, [148780] Altjira on 2024-11-11 UT, and [612582] 2003 QY111 on 2024-11-13 UT. Lempo and Altjira are hierarchical three-body systems, a valuable source of information for improving solar system formation theories. 2003 QY111 is a suspected binary system for which only the rotational light curve amplitude has been measured [0.72 mag in 2003 and 0.2 mag in 2017]. We request a total of 1 hour of Target of Opportunity time, i.e., 30 minutes per stellar occultation event, to observe a total of 2 events during this semester. The 30-minute interval allows for time series imaging of ~ 15 minutes before and after the stellar occultation to set a baseline and detect potential structures and/or satellites. This will also be minimally disruptive to the telescope schedule. PROGRAM_ABSTRACT_END