Light curve of MHO 3252 Y3 in the K band, shown in red. The data were obtained with the IRIS telescope (filled circles) and UKIRT and the Fraunhofer Telescope (open star symbols) from 2012 to 2017. For comparison, the IRIS photometry of two apparently constant stars in the field is also shown (gray color), to demonstrate the reliability of the photometry and the typical errors involved in the IRIS telescope photometry of similarly bright stars. Two major dimming events, ≈2 mag deep, occurred in 2014 and 2016, and minor dimming events were observed in 2013 and again in 2017.