How to measure the apparent magnitude of a star

The measurement of magnitude is photometric measurement, which refers to the measurement of radiation flow from limited band, referred to as photometric measurement, which is completed by telescope and radiation receiver and generally expressed by magnitude. The basic principle of photometry is that under the same conditions, the same radiation flow can make the detection system produce the same "response". According to this, the star to be measured is compared with the star with known magnitude, and the brightness or luminosity of the celestial body to be measured can be calculated according to the "response" of the detection system to them, and then the magnitude of the star to be measured can be calculated. There are many methods to measure the brightness of celestial bodies, the common ones are: visual photometry, photographic photometry and photoelectric photometry. The corresponding magnitude is called visual magnitude, photographic magnitude and photoelectric magnitude. Photoelectric photometry has obvious advantages and is the most widely used photometry method at present.