# # Program information file # PROGRAM_ID 2024A027 PROGRAM_TITLE Stellar occultation by the large trans-Neptunian object Quaoar PROGRAM_INV1 Amanda Sickafoose PROGRAM_INV2 Carlos Zuluaga PROGRAM_INV3 Michael Person PROGRAM_INV4 Stephen Levine PROGRAM_INV5 PROGRAM_SCICAT Centaurs / TNOs / KBOs PROGRAM_ABSTRACT_BEG Stellar occultations are one of the most accurate ground-based methods to measure sizes, shapes, and atmospheres of distant bodies in the Solar System. The capabilities of MORIS+SpeX, combined with Hawaii's unique geographic location, have proven successful for observing stellar occultations by Trans-Neptunian Objects [TNOs]. We propose for 4 hours to observe a predicted stellar occultation by the large TNO [50000] Quaoar. Recent occultation observations of Quaoar have proposed surrounding rings or ring arcs: a successful observation would better characterize surrounding material and provide additional insight into possible activity processes. The UT mid-time for the predicted Quaoar event is on 24 June 13:09 UT. We request 4 hours, to observe [i] at high cadence for +/-20 min centered on the predicted and [ii] long-exposure, calibration frames before and after, when the star and object are well separated. MORIS will be run with no filter at the fastest cadence that allows for a light-curve signal-to-noise of at least a few tens: for this target, the resulting integration time is 0.06 sec. SpeX will be employed to obtain simultaneous K-band image for all the events. Visible data are used to constrain object sizes and atmospheres, as well as the extent and structure of surrounding material. Multi-color data provide an additional level of characterization, through providing insight into [i] particle sizes in atmospheric haze or surrounding material and [ii] nucleus shapes, through central-flash modeling. PROGRAM_ABSTRACT_END