CK Aqr time keeping. Evidence for a ternary [Observed: 2005-20]
Photometric measurements of the contact binary system CK Aqr are presented. 49 times of minimum were obtained between 2005 and 2020. Along with already published observations, this allows the derivation of an improved ephemeris. The resulting O-C diagram shows oscillations which are interpreted as the light time travel effect due to a third component, with a period of 8.2 years.

VZ Lib: a contact binary in a ternary system [Observed: 2014 (1 session, 1 ToM), 2016 (1 session, 1 ToM), 2018 (1]
New photometric observations are presented for this contact binary in a ternary system. A total of 113 times of minimum are analyzed and are found to be in agreement with the ephemeris of Liao et al (2019).

VY Cet: a contact binary in a ternary system [Observed: 26 Dec 2006, 3 Nov 2007, 30 Jan 2009, 31 Oct 2014]
Time series of this contact binary in a ternary system are presented. 3 ToMs are measured along with the B-V and V-R_c colors.

VZ Lib: a contact binary in a ternary system [Observed: 2007-2009, 14 sessions]
Time series of this eclipsing contact binary are reported and times of minima (ToM) of the eclipses are measured. This system has a third component. From the O-C analysis of the observed ToM and of those in the literature, the orbital parameters of the third body can be derived: the orbital period is 34.8 yr and the inclination is 11.5 °.

UX Mon: time keeping and modelling of a binary [Observed: 13 Dec 2007, 11-16, 18 Feb, 8, 13, 14 March, 1, 4, 25, 29]
Time series of this eclipsing binary system with extra variability are presented. The O-C analysis suggests the presence of a third star. The observations are modelled with BinaryMaker3 and parameters of the system are derived.