We determine the ephemeris by measuring the mideclipse time from the CHIMERA g lightcurve . We then use the best model from the Chimera g data and use it fit all ZTF data . In addition , we noticed that there is one non - detection on 2012 - 11 - 1 in Palomar Transient Factory data ( out of 94 observations ) . We add this epoch with half the eclipse duration as uncertainty as a prior ( BJD T DB = 2456232.8854 ± 0.0018 ) . This results in an ephemeris of : BJD(T DB ) = 2459045.985194(2 ) + 0.431 920 8 ( 14 ) ( 1 )