Encountering the mystery of the first black hole: An interview with Paul Murdin, a key figure in black hole discovery.

The Isaac Newton Telescope (INT), a vital instrument in astronomy, made a groundbreaking discovery about the changing nature of Seyfert galaxies. This telescope, though not a giant, has left an indelible mark on the cosmos, thanks to the work of Dr. Paul Murdin and his team.

The INT was initially stationed at Herstmonceux Estate in East Sussex, UK, but due to the unforgiving English weather, it was moved to the Roque de los Muchachos Observatory on the island of La Palma in the 1980s. This relocation was overseen by Dr. Murdin, who was also instrumental in the building of the William Herschel Telescope in La Palma.

Dr. Murdin's tenure with the INT began in its heyday, a period marked by significant discoveries. One such discovery was the first identification of a black hole in Cygnus X-1, a binary star system. This remarkable achievement was made in 1971, in partnership with Louise Webster.

The binary period of the black hole in Cygnus X-1 is five and a half days, requiring consistent access over long periods. This was a challenge with the INT, designed to benefit university astronomers but offering limited opportunities for completing a program of work in a short trip. However, researchers who were resident at the site could take advantage of good weather and make substantial progress.

Dr. Murdin's dedication to the INT was unwavering. He competed with other users for access and also got priority when equipment was being tested. His commitment paid off when he was involved in the first discovery of a black hole, a feat that earned him a permanent employee position.

The discovery of the black hole in Cygnus X-1 was made using the INT. This breakthrough led to a series of papers, the first of which was authored by Michael Penston about the changing nature of a Seyfert galaxy.

Dr. Murdin's contributions to astronomy did not end with the INT. He was chosen as one of the first members of staff at the Anglo-Australian Observatory, furthering his impact on the field.

In an interview conducted in 2017, Dr. Murdin reflected on his time with the INT, sharing anecdotes about his work and offering insights into the challenges and triumphs of the era. Despite the telescope's humble size and cramped operating conditions, its impact on astronomy was anything but small.

Tragically, Louise Webster passed away on 29 September 1990, leaving behind a legacy of groundbreaking discoveries and a profound influence on the field of astronomy. Her work with Dr. Murdin on the first ever clear identification of a black hole will forever be remembered as a milestone in the history of space exploration.

The Isaac Newton Telescope, with its significant discoveries and contributions to our understanding of the universe, was inaugurated by Queen Elizabeth II on 1 December 1967. Its legacy continues to inspire and guide astronomers today.

Encountering the mystery of the first black hole: An interview with Paul Murdin, a key figure in black hole discovery.