2.2.5.1 Spacecraft Illumination
The Perun 1p is freely rotating after injection, basic assumption is 3 full rotations in a minute (different angular velocity does not affect essentially total illumination). Specifics of this Perun 1p is the illumination of its individual plates, the reference altitude being 600 km.
Rotation is determined by three angles: yaw (z axis), pitch (y axis) and roll (x axis). The angular time rates of individual angles are essentially random, depending on the mechanism of injection (injection direction is assumed to be along the z body fixed axis) and the location of the Perun 1p centre of mass with respect to its geometric centre, more exactly, depending on structure of its moment of inertia tensor. For demonstration purpose angular time rates of individual angles is taken randomly but representing 3 full rotations in a minute. 24-hour typical illumination of individual sides of the Perun 1p, when in orbit with 60deg inclination, is shown in Figure. S gives the total illumination, which is given in units of their area (for u cube all its sides have the same area). Zero illumination signifies the period of eclipse.

24-hour plates illumination orthogonal to the BFRF unit vectors (60 deg orbit)
                                             

Illumination within shorter time interval reveals its oscillations, as shown in Figure, and only up to three sides of the Perun 1p are simultaneously illuminated.
                                             
Average daily exposure of the Perun 1p to the Sun, on yearly basis, is 16 hours, with the deviation margin of about 0.5 hours.
In the sun-synchronous orbit the illumination has more complex structure. For the 600 km orbit the optimal inclination angle of the Perun 1p orbit is 97.7 deg, when the orbit plane rotates around the Earth axis by 2.38 deg per year. However, if the angle is missed by 0.50 the rotation increases to approximately 22 deg per year, and if by 1 deg then uncreases to 45 deg. In the sun-synchronous orbit the Perun 1p average daily exposure to the Sun is 15.2 hours, if the initial RAN is 0 deg. If RAN is 90 deg then exposure is 24 hours, meaning that if the initial inclination of the Perun 1p orbit plane is missed by small angle there is no unique telling what time evolution of its Sun exposure would be. Even a small perturbation of the orbit, to various external effects, would remove the Perun 1p from its Sun Synchronous orbit. The satellites therefore need propulsion systems to keep them within the margins of this orbit, which in the presented mission the systems is not planned.