Results from a Stellar Occultation by (623) Chimaera
Abstract
We present results from a stellar occultation by the asteroid (623) Chimaera on October 21st, 2025, when it passed in front of V magnitude 13.86 star UCAC4 626-004193. Chimaera is the largest asteroid in the Chimaerid asteroid family and will be subject to a spacecraft flyby in the 2030s. Eighteen telescopes were deployed, spanning the United States from Arizona to North Carolina, incrementally spaced by ∼4.4\,km with respect to the cross-track of the shadow. In total, sixteen telescopes collected useful data. This multi-chord observation, when compiled into a single sky-plane plot, suggests a profile which is well-described by an elongated elliptical fit, with a semi-major axis a=26.2±0.8 km and a semi-minor axis b=16.0±1.0 km. The projected area from ellipse fitting is 1316 km2, and a limb fit is calculated to enclose 1312 km2. Photometry collected in the Gaia G band over a seven-month period coinciding with the occultation corresponds to a geometric albedo pG=0.059±0.005; comparing with archival occultation observations and direct observations gives pG=0.051±0.004 and pV=0.051±0.004. We compare occultation sky-plane projections with 3-D modeling from inversion techniques and demonstrate that the models can accurately predict the orientation of Chimaera at the time of each occultation.
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BibTeX
@misc{oakey2026results,
title = {{Results from a Stellar Occultation by (623) Chimaera}},
author = {Phillip Oakey and Keya Garg and Andrey Moore and Altony Foote and Michael F. Skrutskie and Anne J. Verbiscer and Matthew Nelson and Marc W. Buie and Diego Gomez and Lauren Daszynski and Charlie Dorsey and Roger Venable and Vadim Nikitin and Joan Dunham and David Dunham and Nadara Hudson and Colin Surovell and Norman Carlson and Georgia Clickner and James Beck and Mark Chernov and Tristan Howdyshell and Paul D. Maley and Ted Barnes and John DiPasquale and Casey York and Ted Blank and Henk de Groot},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.08041},
eprint = {2611.08041},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.08041},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Results from a Stellar Occultation by (623) Chimaera
AU - Phillip Oakey
AU - Keya Garg
AU - Andrey Moore
AU - Altony Foote
AU - Michael F. Skrutskie
AU - Anne J. Verbiscer
AU - Matthew Nelson
AU - Marc W. Buie
AU - Diego Gomez
AU - Lauren Daszynski
AU - Charlie Dorsey
AU - Roger Venable
AU - Vadim Nikitin
AU - Joan Dunham
AU - David Dunham
AU - Nadara Hudson
AU - Colin Surovell
AU - Norman Carlson
AU - Georgia Clickner
AU - James Beck
AU - Mark Chernov
AU - Tristan Howdyshell
AU - Paul D. Maley
AU - Ted Barnes
AU - John DiPasquale
AU - Casey York
AU - Ted Blank
AU - Henk de Groot
PY - 2026
DA - 2026/11/05
PB - arXiv
DO - 10.48550/arxiv.2611.08041
UR - https://arxiv.org/abs/2611.08041
AB - We present results from a stellar occultation by the asteroid (623) Chimaera on October 21st, 2025, when it passed in front of V magnitude 13.86 star UCAC4 626-004193. Chimaera is the largest asteroid in the Chimaerid asteroid family and will be subject to a spacecraft flyby in the 2030s. Eighteen telescopes were deployed, spanning the United States from Arizona to North Carolina, incrementally spaced by ∼4.4\,km with respect to the cross-track of the shadow. In total, sixteen telescopes collected useful data. This multi-chord observation, when compiled into a single sky-plane plot, suggests a profile which is well-described by an elongated elliptical fit, with a semi-major axis a=26.2±0.8 km and a semi-minor axis b=16.0±1.0 km. The projected area from ellipse fitting is 1316 km^2, and a limb fit is calculated to enclose 1312 km^2. Photometry collected in the Gaia G band over a seven-month period coinciding with the occultation corresponds to a geometric albedo p_G=0.059±0.005; comparing with archival occultation observations and direct observations gives p_G=0.051±0.004 and p_V=0.051±0.004. We compare occultation sky-plane projections with 3-D modeling from inversion techniques and demonstrate that the models can accurately predict the orientation of Chimaera at the time of each occultation.
ER -