Multi-color photometric light curves of NO Cam in V R _ { C } and I _ { C } bands are obtained and analyzed simultaneously using the Wilson-Devinney ( W-D ) program .
The solutions suggest that NO Cam is an A-subtype overcontact binary with its mass ratio to be q = 0.439 and a contact degree of f = 55.5 \% .
The small temperature difference ( \Delta T = 44 K ) between its two components indicates that the system is under thermal contact .
The high orbital inclination ( i = 84.5 ^ { \circ } ) strengthens our confidence in the parameters determined from the light curves .
All available times of minimum light are collected and period variations are analyzed for the first time .
The O - C curve reveals that its period is increasing continuously at a rate of dP / dt = +1.46 \times { 10 ^ { -9 } } , which can be explained by mass transfer from the less massive component to the more massive one .
After the upward parabolic variation is subtracted , the residuals suggest that there may be a cyclic variation with a period of 2.23 years and an amplitude of A _ { 3 } = 0.00153 days , which may due to the light-travel time effect ( LTTE ) arising from the gravitational influence of a close-in tertiary component .
The close-in companion reveals that early dynamic interaction among triple system may have played very important role in the formation of the W UMa type binaries .