Summary of three observed multiple systems in the Orion Trapezium Cluster. Middle: Orion nebula in the background and zoom on the Orion Trapezium Cluster (θ¹) stars in the inset. Blue arrows mark the separation between FT and SC. Upper: orbit of θ¹ Ori B₆ around the eclipsing binary θ¹ Ori B₁₅ at the center. We use θ¹ Ori A at a separation of 8.85 arcsec as the FT. Note that θ¹ Ori B₆ has completed more than one orbital revolution between 2017 and 2021. Left: orbit of θ¹ Ori C₂ around the primary star θ¹ Ori C₁ at the center. θ¹ Ori C₂ has completed more than two orbital revolutions. Literature data points are measurements taken from Weigelt et al. (1999), Schertl et al. (2003), Kraus et al. (2007, 2009), Patience et al. (2008), and Grellmann (2013). The observation was performed with θ¹ Ori A at a separation of 12.86 arcsec as the FT. Right: orbit of θ¹ Ori D₃ around the primary star θ¹ Ori D₁ at the center. We use θ¹ Ori C at a separation of 13.41 arcsec as the FT. θ¹ Ori D₃ has revolved 20 times between the first and last data point. Background image and zoom from ESO/M. McCaughrean et al. (AIP) 2001.