How to determine the position of asteroids in the starry sky?

In order to determine the orientation of asteroids in the starry sky, visual and photographic observation methods can be used. However, if we want to accurately measure the brightness or magnitude of asteroids, we must adopt a method called photoelectric photometry. This method uses a photovoltaic cell, and the light emitted by an asteroid shines on the photovoltaic cell through a telescope, and the energy of the light is converted into electricity. We use an ammeter to measure the current generated by the photocell. Because this current is directly proportional to the light energy irradiated into the photovoltaic cell, the current is an indicator of the brightness of the asteroid. If an asteroid is compared with a star of known size, its size can be calculated. In this work, it is found that the brightness of many asteroids varies periodically from several hours to more than ten hours.