What kind of telescope was used to get pictures of the black hole?
57688129#4
Alongside Heino Falcke and Michael Kramer, he received a
14 million euro research grant of the European Research Council for further
studies into black holes with the goal to construct a black hole camera using the Event Horizon Telescope. This would allow testing of general theory of relativity by creating an image of the black hole shadow.
Luciano Rezzolla
34573309#0
The Event Horizon Telescope (EHT) is a project to create a large telescope array consisting of a global network of radio telescopes and combining data from several very-long-baseline interferometry (VLBI) stations around the Earth. The aim is to observe the immediate environment of the supermassive black hole Sagittarius A* at the center of the Milky Way, as well as the even larger black hole in the supergiant elliptical galaxy Messier 87, with angular resolution comparable to the black hole's event horizon.
Event Horizon Telescope
54183162#1
O'Dowd studies black holes and quasars by using gravitational lensing. He uses the Hubble Space Telescope to look at distant quasars that line up with nearby galaxies. Those galaxies act like additional lenses on the telescope, allowing scientists to see much closer to the black hole than is otherwise possible.
Matt O'Dowd (astrophysicist)
840191#8
In a paper published October 31, 2018, the discovery of conclusive evidence that Sagittarius A* is a black hole was announced. Using the GRAVITY interferometer and the four telescopes of the Very Large Telescope (VLT) to create a virtual telescope 130 metres in diameter, astronomers detected clumps of gas moving at about 30% of the speed of light. Emission from highly energetic electrons very close to the black hole was visible as three prominent bright flares. These exactly match theoretical predictions for hot spots orbiting close to a black hole of four million solar masses. The flares are thought to originate from magnetic interactions in the very hot gas orbiting very close to Sagittarius A*.
Sagittarius A*
56326541#2
The telescope will be used to study the event horizons of black holes and to test how general relativity behaves in environments with extreme gravity.
Greenland Telescope
5280804#2
Filippenko developed and runs the Katzman Automatic Imaging Telescope (KAIT), a fully robotic telescope which conducts the Lick Observatory Supernova Search (LOSS), the most successful nearby supernova search. He is also a member of the Nuker Team which uses the Hubble space telescope to examine supermassive black holes and determined the relationship between a galaxy's central black hole's mass and velocity dispersion. The Thompson-Reuters "incites" index ranked Filippenko as the most cited researcher in space science for the ten-year period between 1996 and 2006.
Alex Filippenko
37775617#4
Subsequent investigations employed adaptive optics to acquire a better estimate of the mass of the black hole.
One group made observations using the Gemini Near Infrared Integral Field Spectrometer to better determine the mass of the black hole at the center of NGC 1277. The group used similar models to that of van den Bosch, but with higher spatial resolution. After using stellar dynamics and luminosity models to estimate the mass of the black hole, they came to a mass of , similar to the estimate from the follow-up study done by Emsellem, which estimated a mass between 2–5 billion solar masses. 
More recently, a new group made observations using the larger Keck Telescope with superior spatial resolution, and calculated that a black hole with mass fits best. Moreover, this value is an order of magnitude smaller than first reported by van den Bosch, and was noted to probably be an upper limit due to the edge-on rotating disk in NGC 1277.
NGC 1277
2639335#99
(May 2) First visual proof of existence of black holes is published. Suvi Gezari's team in Johns Hopkins University, using the Hawaiian telescope Pan-STARRS 1, record images of a supermassive black hole 2.7 million light-years away that is swallowing a red giant.
Timeline of astronomy
960596#5
Two black holes of between 10 and 20 solar masses each have been discovered, initially with the Very Large Array radio telescope in New Mexico, and corroborated by the Chandra X-ray telescope, in 2012. Their detection implies that gravitational ejection of black holes from clusters is not as efficient as was previously thought, and leads to estimates of a total 5 to 100 black holes within M22. Interactions between stars and black holes could explain the unusually large core of the cluster.
Messier 22
42123974#1
This determination was made by a team led by Rubens Reis of the University of Michigan using NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton telescopes. The team observed the X-rays generated in the innermost regions of the disk circling and feeding the black hole that powers the quasar. By measuring the radius of the disk, the astronomers were able to calculate the black hole's rotational speed, which was almost half the speed of light. The rapid spin of the quasar indicates that the black hole is being fed by a vast supply of gas and dust.
RX J1131-1231
215706#7
The Hubble Space Telescope, launched in 1990, provided the resolution needed to perform more refined observations of galactic nuclei. In 1994 the Faint Object Spectrograph on the Hubble was used to observe Messier 87, finding that ionized gas was orbiting the central part of the nucleus at a velocity of ±500 km/s. The data indicated a concentrated mass of lay within a span, providing strong evidence of a supermassive black hole. Using the Very Long Baseline Array to observe Messier 106 , Miyoshi et al. (1995) were able to demonstrate that the emission from an HO maser in this galaxy came from a gaseous disk in the nucleus that orbited a concentrated mass of , which was constrained to a radius of 0.13 parsecs. They noted that a swarm of solar mass black holes within a radius this small would not survive for long without undergoing collisions, making a supermassive black hole the sole viable candidate.
Supermassive black hole