We report the analysis of a planetary microlensing event AT2021uey. The event was observed outside the Galactic bulge and was alerted by both space- (Gaia) and ground-based (ZTF and ASAS-SN) surveys. From the observed data, we find that the lens system is located at a distance of 1 kpc and comprises an M-dwarf host star of about half a solar mass, orbited by a Jupiter-like planet beyond the snowline. The source star could be a metal-poor giant located in the halo according to the spectral analyses and modelling. Hence, AT2021uey is a unique example of the binary-lens event outside the bulge that is offered by a disc-halo lens-source combination.
@article{arxiv.2503.22331,
title = {AT2021uey: A planetary microlensing event outside the Galactic bulge},
author = {M. Ban and P. Voloshyn and R. Adomaviciene and E. Bachelet and V. Bozza and S. M. Brincat and I. Bruni and U. Burgaz and J. M. Carrasco and A. Cassan and V. Cepas and F. Cusano and M. Dennefeld and M. Dominik and F. Dubois and R. Figuera Jaimes and A. Fukui and C. Galdies and A. Garofalo and M. Hundertmark and I. Ilyin and K. Kruszynska and V. Kulijanishvili and T. Kvernadze and L. Logie and M. Maskoliunas and P. J. Mikolajczyk and P. Mroz and N. Narita and E. Pakstiene and J. Peloton and R. Poleski and J. K. T. Qvam and S. Rau and P. Rota and K. A. Rybicki and R. A. Street and Y. Tsapras and S. Vanaverbeke and J. Wambsganss and L. Wyrzykowski and J. Zdanavicius and M. Zejmo and P. Zielinski and S. Zola},
journal= {arXiv preprint arXiv:2503.22331},
year = {2025}
}