OGLE-2012-BLG-0563: Relative Proper Motion Constraint from Keck Follow-up finds the correct Lens

@misc{bhattacharya2026ogle2012blg0563,
  title = {{OGLE-2012-BLG-0563: Relative Proper Motion Constraint from Keck Follow-up finds the correct Lens}},
  author = {Aparna Bhattacharya and David P. Bennett and Jean Phillippe Beaulieu and Ian A. Bond and Kansuke Nunota and Jessica R. Lu and Joshua W. Blackman and Andrew A. Cole and Akihiko Fukui and Jean Baptiste Marquette and Clement Ranc and Natalia Rektsini and Sean K Terry and Aikaterini Vandorou},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.30310},
  eprint = {2610.30310},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.30310},
  note = {CC0},
}

TY  - UNPB
TI  - OGLE-2012-BLG-0563: Relative Proper Motion Constraint from Keck Follow-up finds the correct Lens
AU  - Aparna Bhattacharya
AU  - David P. Bennett
AU  - Jean Phillippe Beaulieu
AU  - Ian A. Bond
AU  - Kansuke Nunota
AU  - Jessica R. Lu
AU  - Joshua W. Blackman
AU  - Andrew A. Cole
AU  - Akihiko Fukui
AU  - Jean Baptiste Marquette
AU  - Clement Ranc
AU  - Natalia Rektsini
AU  - Sean K Terry
AU  - Aikaterini Vandorou
PY  - 2026
DA  - 2026/10/21
PB  - arXiv
DO  - 10.48550/arxiv.2610.30310
UR  - https://arxiv.org/abs/2610.30310
AB  - We present Keck/NIRC2 adaptive optics imaging results of planetary microlensing event OGLE-2012-BLG-0563. We find that the OGLE-2012-BLG-0563L planetary system consists of a 1.12 +/- 0.09 Jupiter-mass planet orbiting a 0.81 +/- 0.04 solar-mass host star at a distance of 5.49 +/- 0.56 kpc from the Sun. This event has a lens-source separation of 23.28 +/- 0.48 mas, which is the smallest lens-source separation measured to date with Keck AO data. We find that the incorrect solution - which identifies the Northeast (NE) star as the source star - is favored if one only considers the discovery paper, the Fukui et al. (2015) solution, or an unconstrained model. However, by performing an image-constrained light curve model fit using the relative proper motion direction constraint from the Keck follow-up data, we demonstrate that the correct solution identifies the NE star as the lens star. The discrepancy in the unconstrained models is driven by systematics in the FTS and MOA B & C data, alongside the impact of the relative proper motion direction constraints. This outcome offers two important lessons for future Roman data analysis: (1) thoroughly verify systematics across all passbands and identify the precise origin of chi-squared differences, and (2) utilize image-constrained light curve modeling incorporating relative proper motion direction constraints to identify the correct lens.
ER  -