An analysis of binary microlensing event OGLE-2015-BLG-0060
Bennett, D. P.; Soszyński, I.; Udalski, A.; Szymański, M. K.; Pietrukowicz, P.; Skowron, J.; Mróz, P.; Poleski, R.; Kozłowski, S.; Ulaczyk, K.; Yamada, T.; Mao, S.; Steele, I. A.; Snodgrass, C.; Horne, K.; Wang, Y.; Korhonen, H.; Southworth, J.; Shibai, H.; Mancini, L.; Sumi, T.; Bachelet, E.; Tsapras, Y.; Hundertmark, M.; Cassan, A.; Rabus, M.; Evans, D. F.; Dominik, M.; Jørgensen, U. G.; Fukui, A.; Suzuki, D.; Koshimoto, N.; Yonehara, A.; Bozza, V.; Peixinho, N.; Bramich, D. M.; Figuera Jaimes, R.; Wambsganss, J.; Schmidt, R.; Ciceri, S.; Wertz, O.; Pawlak, M.; Andersen, M. I.; Burgdorf, M. J.; Beaulieu, J. P.; Popovas, A.; Nagakane, M.; Rattenbury, N.; Abe, F.; Bhattacharya, A.; Donachie, M.; Hirao, Y.; Itow, Y.; Li, M. C. A.; Matsubara, Y.; Miyazaki, S.; Muraki, Y.; Ranc, C.; Sullivan, D. J.; Tristram, P. J.; Menzies, J.; Street, R.; Skottfelt, J.; D'Ago, G.; Hinse, T. C.; Rahvar, S.; Evans, P.; Tronsgaard, R.; Kerins, E.; Calchi Novati, S.; Scarpetta, G.; Ling, C. H.; Masuda, K.; Ohnishi, K.; Marquette, J. B.; Kuffmeier, M.; Sharan, A.; Kawasaki, K.; Euteneuer, E.; Asakura, Y.; Saito, To; Robonet Team
Germany, France, United States, Poland, Italy, Australia, United Arab Emirates, United Kingdom, China, South Africa, Switzerland, Denmark, Finland, Chile, Portugal, South Korea, Iran, Belgium, Japan, New Zealand
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_{\star 1} = 0.87 ± 0.12 M_{⊙} and M_{\star 2} = 0.77 ± 0.11 M_{⊙}. The distance to the lensing system is 6.41 ± 0.14 kpc and the projected separation between the two components is 13.85 ± 0.16 au. Alternative interpretations are also considered.