The application of photography in astronomy was of great importance due to its many advantages over visual observation. In 1839, the French inventor Louis Jacques Mande Daguerre (1787-1851) invented a method of obtaining a hidden image on a metal plate of silver iodide, which he then showed by mercury vapor. The first portraits of people (daguerreotypes) appeared. The Director of the Paris Observatory, Dominique François Arago (1786-1853), in his report to the French Academy of Sciences on August 19, 1839, pointed out the extensive prospects for the application of photography in science, in particular in astronomy.
Already in 1840, the first daguerreotypes of the Sun and Moon, then the stars, the solar corona, and the Sun"s spectrum were obtained. The big disadvantage of daguerreotypes was the impossibility of their replication. Daguerreotype was made in one copy, and in order to get another, it was necessary to take off again. In 1851 the Englishman F. Scott-Archer invented a wet colloidal method when the plates were filled with a layer of colloid containing silver iodide shortly before use. The latter served as a light-sensitive material. The first experiments on photographing celestial bodies in this way showed a significant advantage of the wet colloidal method over the daguerreotype one.
Exposure time was reduced by more than 100 times, the images contained numerous details. The greatest success in the application of the wet colloidal method reached the English amateur astronomer Varren Deloru (1815-1889). As the owner of a paper mill, he built an observatory near London and a good telescope with which to conduct photography.
At his suggestion, the British Astronomical Association built a special observatory and a solar photogeliograph device in Q. In 1850, the association built a special observatory and a solar photogeliograph device in Q. William and George Bondy, father and son, took the first photograph of a star (Vega). In 1872, he took a photograph of the star (Vega). Henry Draper obtained her first spectrogram, which showed the absorption lines. Photography increasingly penetrated the practice of astronomical research. In 1891, the first small planet was discovered with its help. It was 323 Brucius. Photography techniques were gradually improved and photographic materials were improved.
Yellow, red and infrared spectrums became available for photography. To observe the complete solar eclipse on August 19, 1887, in Russia, in the Volga town of Yurievets (near Nizhny Novgorod), came the director of the Potsdam Observatory, Professor German Carl Vogel (1841-1907). He intended to photograph the red part of the chromosphere and crown spectrum, which at that time could not be taken with the help of dry bromide gelatin plates used since 1871. For this purpose, Vogel made a special liquid-based emulsion, the evening before the eclipse he poured his plates with a colloidal layer and dried them. He exhibited his records in the "photo lab", which he served as an ordinary Russian bath.
The ceiling was covered with earth, which was crumbling from slamming doors. Poor Vogel did not think that in the room where people were washing, the earth could fall from the ceiling. However, he got out of the situation - he observed the spectrum visually. In ancient times, astronomers divided the stars into six classes of shine - the stars. This value has nothing to do with the size of the star, it characterizes only the amount of light. In 1857, the English astronomer Norman Robert Pogson (1829-1891) proposed the scale of star values used up to now, in which the difference in one-star value corresponds to the ratio of brightness, which is 2. 512 times.
This number is chosen for convenience because of 2, 512 = 100. Differences in 5-star values correspond to the ratio of brightness precisely 100 times, and for the difference, for example, in 15 values it is equal to 1 million. For this purpose, special devices - photometers - were used. Thanks to these methods, accurate observations of changes in the brightness of variable stars became possible. Observation astrophysics developed rapidly in the XX century. But in this century, for the first time, it was preceded by theoretical astrophysics, which covered the entire universe in a single glance.