TCP J18010186-2951258 is likely not a binary microlensing event
ATel #11883; P. Mroz, A. Udalski (Warsaw University Observatory)
on 24 Jul 2018; 09:20 UT
Credential Certification: Przemek Mroz (pmroz@astrouw.edu.pl)
Subjects: Optical, Microlensing Event
Nucita et al. (ATel #11882) reported that the light curve of the microlensing event TCP J18010186-2951258 (ATel #11853) shows deviations from the single lens model that could be interpreted as a signature of the binary lens with the mass ratio q = 8.3e-3.
This event is located in the field BLG513 that is regularly monitored by the
OGLE-IV Survey. The archival 22-year-long light curve of the source reveals semi-regular low-amplitude variability that is typical of OGLE small amplitude red giants. The strongest pulsation period is 155.4 d, but the light curve shows additional modulation on timescales of 10-20 d. Although the amplitude of variability in the baseline is small (0.03 mag or 3% of the flux in the I band), it is magnified by a factor ~30 during the microlensing event.
Deviations from the single lens model in the light curve of TCP J18010186-2951258 are likely caused by the variability of the source star, not by the binarity of the lens.
