Gennadij Borisov

Gennadiy Vladimirovich Borisov (; born 1962 in Kramatorsk) is a Crimean telescope maker and amateur astronomer who discovered the first-known interstellar comet, 2I/Borisov, in 2019.

Work Borisov works as an engineer at the of the Sternberg Astronomical Institute of Moscow State University. There, he maintains the telescopes, but does not make observations himself. He also works with Astronomicheskiy Nauchnyy Tsentr JSC, creating experimental telescopes in collaboration with Roscosmos.

+ Comets discovered by Gennadiy Borisov Designation Type C/2013 N4 (Borisov) long-period C/2013 V2 (Borisov) hyperbolic C/2014 R1 (Borisov) near-parabolic C/2014 Q3 (Borisov) Halley-type C/2015 D4 (Borisov) long-period C/2016 R3 (Borisov) long-period C/2017 E1 (Borisov) hyperbolic 2I/Borisov hyperbolic, interstellar C/2019 V1 (Borisov) near-parabolicC/2020 Q1 (Borisov)long-period C/2021 L3 (Borisov) hyperbolic C/2023 T2 (Borisov) near-parabolic C/2024 V1 (Borisov) long-period C/2025 B2 (Borisov) hyperbolic C/2025 J1 (Borisov) near-parabolic C/2025 V1 (Borisov) hyperbolic

Borisov pursues astronomy in his spare time at his personal observatory MARGO located in Nauchnyi, in the southern part of the Crimean peninsula. Between 2013 and 2019, he discovered nine comets and several near-Earth objects (NEOs) such as . These discoveries were made using telescopes he designed and built himself: GENON (2 comets), GENON Max (5 comets) and the HGB-650 0.65 m telescope (2 comets, including 2I/Borisov). In 2014, Borisov received two Edgar Wilson Awards for his discoveries of C/2013 N4 and C/2013 V2. Borisov also discovered the asteroid 2023 BU, another near-Earth object that passed within 4,000 km of the Earth in January 2023. He also observed cometary activity on NEO (523822) 2012 DG61, making it a Near-Earth Comet (NEC). The cometary activity was later independently discovered and confirmed by scientists of the Active Asteroids project. I measured its coordinates and consulted the Minor Planet Center database. Turned out, it was a new object. Then I measured the near-Earth object rating, it is calculated from various parameters, and it turned out to be 100% – in other words, dangerous. In such cases I must immediately post the parameters to the world webpage for confirmation of dangerous asteroids. I posted it and wrote that the object was diffuse and that it was not an asteroid, but a comet.

The discovery of 2I/Borisov by Gennadiy Borisov has been compared to the discovery of Pluto by Clyde Tombaugh. Tombaugh was also an amateur astronomer who was building his own telescopes, although he discovered Pluto using Lowell Observatory's astrograph.

Discovery of 2023 BU On January 21, 2023, Borisov discovered the relatively small asteroid 2023 BU, only 5 days before it would pass an initially calculated from the centerpoint of Earth, closer than geostationary satellites but further than low Earth orbit satellites.

Views Borisov thinks that soon amateur astronomers will no longer be able to discover new comets: "In 2016, only I discovered a comet. In 2013, there were seven of us. Every year there are less and less. There are more and more huge telescopes. Amateurs will soon have nothing left."