# An analysis of binary microlensing event OGLE-2015-BLG-0060

## TL;DR

This paper thoroughly analyzes a binary microlensing event using extensive multi-telescope data, successfully constraining the physical parameters of the lens system and demonstrating the importance of follow-up observations for detailed event characterization.

## Contribution

First comprehensive coverage of an anomalous microlensing event enabling precise physical parameter estimation of the lens system.

## Key findings

- Lens system consists of two stars with masses ~0.87 and 0.77 solar masses.
- Distance to the lensing system is approximately 6.41 kpc.
- Projected separation between the binary components is about 13.85 AU.

## Abstract

We present the analysis of stellar binary microlensing event OGLE-2015-BLG-0060 based on observations obtained from 13 different telescopes. Intensive coverage of the anomalous parts of the light curve was achieved by automated follow-up observations from the robotic telescopes of the Las Cumbres Observatory. We show that, for the first time, all main features of an anomalous microlensing event are well covered by follow-up data, allowing us to estimate the physical parameters of the lens. The strong detection of second-order effects in the event light curve necessitates the inclusion of longer-baseline survey data in order to constrain the parallax vector. We find that the event was most likely caused by a stellar binary-lens with masses $M_{\star1} = 0.87 \pm 0.12 M_{\odot}$ and $M_{\star2} = 0.77 \pm 0.11 M_{\odot}$. The distance to the lensing system is 6.41 $\pm 0.14$ kpc and the projected separation between the two components is 13.85 $\pm 0.16$ AU. Alternative interpretations are also considered.