also taken by follow-up groups during the Moon gap in the OGLE data, and these can be used to verify our results. After the Moon gap, the anomaly lasted for  10 days including one more peak centered on ${\rm HJD'}=6120.9$.

The main peak of the event occurred at $t_0 = 6141.5$. It was just after the Moon passed close to the OGLE-2012-BLG-0406. Unfortunately, a suspicious linear small scale trend is present in our photometry during the four nights starting from ${\rm HJD'} = 6140$. Larger scatter during that time is also present in photometry of nearby red clump stars and in some cases linear trends with $2\sigma$ significance are seen. High sky background or poor seeing conditions (above $1\farcs7$) clearly affected at least nine out of $21$ epochs collected at that time (including all on ${\rm HJD'} = 6142$ and $6143$). It is worth noticing, that $1\farcs5$ away from the source star there is another star that is $1.1~{\rm mag}$ brighter than the event in the baseline and was $0.3~{\rm mag}$ brighter than the event during the main peak. This neighbor star most likely affected the event photometry, especially at poor seeing conditions. As these factors caused not only larger 