The microlensing event OGLE-2017-BLG-0406 was first discovered on March 27 (HJD'=HJD-2450000=7839) by the Optical Gravitational Lensing Experiment (OGLE) collaboration. The event lies in the OGLE-IV field BLG506, and the observations were conducted at the cadence of once per hour by using the 1.3m Warsaw telescope located at Las Campanas Observatory in Chile.
The Microlensing Observations in Astrophysics (MOA) group independently discovered this event on May 5 (HJD'=7879) by using the MOA alert system. MOA observed this event with 15 minutes cadence by using MOA-II telescope at Mt. John University Observatory in New Zealand.
The event was also independently discovered by the Korean Microlensing Network (KMTNet) survey using its post-season event finder. KMTNet observes toward the Galactic bulge by using three 1.6m telescopes at the Cerro Tololo Inter-American Observatory in Chile (CTIO: KMT-C), and the South African Astronomical Observatory in South Africa (SAAO: KMT-S). Because this event was in an overlapping region between two fields (KMTNet BLG02 and BLG42), the observations were conducted at a 15minute cadence.
On June 2 (HJD'=7907), the Microlensing Follow-up Network (μFUN) collaboration, the Microlensing Network for the Detection of Small Terrestrial Exoplanet (MiNDSTEp) collaboration and Las Cumbres Observatory (LCO) global network of telescope collaboration started high-cadence follow-up observations. μFUN used the following telescopes: the 1.3m CTIO telescope in Chile, the 0.41m Auckland telescope and the 0.36m Farm Cove telescope in New Zealand, and the 0.30m Perth Exoplanet Survey Telescope (PEST), and the 0.25m Craigie telescope in Australia. MiNDSTEp used the 1.54m Danish Telescope at La Silla Observatory in Chile. LCO used the 1.0m telescopes at CTIO in Chile and at SSO in Australia.
We also obtained three near-infrared images taken at different epochs (HJD'~7911, 7918 and 7942). The observations were made with SIRIUS, a simultaneous imager in J, H, and KS bands, covering an area 7.7x.7 arcmin2 with a pixel scale of 0.45" on the 1.4m InfraRed Survey Facility (IRSF) telescope at SAAO.
OGLE-2017-BLG-0406 was observed by the Spitzer space telescope with the 3.6μm (L-band) channel of the IRAC camera. Spitzer started to observe this event on June 26 (HJD'=7931).
(17 data files)....