  We present the photometric analysis of three ultra-short period total
eclipsing binaries in contact configuration, CRTS_J172718.0+431624,
OGLE-BLG-ECL-000104, and OGLE-BLG-ECL-000012, mined from massive astronomical
surveys. Using the available archival light curves (LCs) from Vista Variables
in the Via Lactea (VVV), Optical Gravitational Lensing Experiment (OGLE),
Zwicky Transient Facility (ZTF) and Catalina Sky Survey (CSS) in different
passbands and new multi-band photometric observations with the 2.3 m
Aristarchos telescope at Helmos Observatory, their relative physical parameters
were derived. We explored the parameter space by using PIKAIA genetic algorithm
optimizer. The best photometric solution and error budget estimation was
adopted for each system through MCMC sampling of the global optimum. The
approximate absolute parameters were derived for each contact system adopting
an empirical mass-luminosity relation. All three systems have a mass ratio
lower than 0.5. The exchange between primary and secondary depths of
CRTS_J172718.0+431624 during the years 2016-2022 may be due to spot activity.
In addition, we present a detailed analysis of the first well characterized
shortest period contact eclipsing binary with total eclipses known so far
(OGLE-BLG-ECL-000104). Thanks to VVV and OGLE LCs, new distances were derived
for OGLE-BLG-ECL-000104 and OGLE-BLG-ECL-000012 using empirical
period-luminosity relations. The origin and evolutionary status of all three
ultra-short period contact binaries are thoroughly discussed in the context of
the detached-binary formation channel.
