Very good question. The article I'm reading says "Today, most independent researchers believe that the 1979 flash was caused by a nuclear explosion" What does yours say?
It sounds like early on the US government said it was inconclusive in order to not offend South Africa and Israel. But more recently, people have been saying it was a nuclear test.
> A December 2016 report by William Burr and Avner Cohen of George Washington University's National Security Archive and Nuclear Proliferation International History Project noted that the debate over the South Atlantic flash has shifted over the last few years, on the side of a man-made weapon test.[1] The National Security Archive briefing concluded:
>> A Central Intelligence Agency-sponsored panel of well-respected scientists concluded that a mysterious flash detected by a U.S. Vela satellite over the South Atlantic on the night of 22 September 1979 was likely a nuclear test.
> The newly released research and subsequent report was largely based upon recently declassified documents in files at the National Archives of Gerard C. Smith, a former Ambassador and special envoy on nuclear nonproliferation during Jimmy Carter's presidency.[1][60][5] Smith had once said: "I was never able to break free from the thought that the event was a joint operation between Israel and South Africa." The documents cited a June 1980 U.S. State Department report where Defense Intelligence Agency Vice Director Jack Varona had said the ensuing U.S. investigation was a "white wash, due to political considerations" based on "flimsy evidence". He added that the "weight of the evidence pointed towards a nuclear event" and cited hydroacoustic data analyzed by the Naval Research Laboratory. The data, he suggested, involved "signals ... unique to nuclear shots in a maritime environment" and emanating from the area of "shallow waters between Prince Edward and Marion Islands, south-east of South Africa".[1][5][60]
> In 2018, a new study made the case for the double flash being a nuclear test.[6][7][61][62]
The interesting fact is that there is very little speak of any other nation carrying out a nuclear test. It boiled down to Israel and South Africa, or a sensor glitch/weather fenomena. Kind of fun that the two nations vere the prime suspects although officially "nothing happened".
Also that the 'glitch' happened to occur in very close proximity to two uninhabited* subantarctic islands controlled by South Africa - and that sheep in Western Australia showed higher levels of iodine 131.
*Permanently uninhabited, but there's a research base there.
I spent a year on that island in 2010/2011. There has never been a time where there weren't research personnel at the station since the 50s. It's very hard to believe a nuclear test would be carried out without concern for the safety of the overwintering team or without anybody noticing.
A two to three kiloton nuclear explosion approximately 100 miles east of the island would not be noticeable. The prevailing winds blow east, but the nearest islands are another 400 miles away.
The coordinates of the blast are given as 47°S 40°E, while Prince Edward is at about 38°E. Google maps shows the distance as about 100 miles. Tan(2degrees) x 100 x 5280 gives about 18,400 feet below the horizon at Prince Edward for the elevation of the blast. So any radiation from the blast itself would travel through a lot of shielding water and rock. Possibly the decay of fallout aloft could be detected, but that would only be for gamma radiation at that distance through air. And not many fission products would make it to 18,000 feet from a small bomb.
> It's very hard to believe a nuclear test would be carried out without concern for the safety of the overwintering team or without anybody noticing.
Atomic tests have routinely been carried out with scientific observers nearby, I mean, it's sorta the point of doing one. And as for people noticing, I would imagine apartheid South Africa had their own equivalent of an Official Secrets Act.
I don't disbelieve you, but again - Official Secrets Act. I doubt any of the wintering over scientists had a strong urge to end up on Robben Island for telling someone about the time that they were asked to take a short holiday and not ask too many questions.
Also, the fact that the overwintering teams are all listed as ending their time there in September strongly correlates to the date of the Vela Incident. So entirely plausible to send the winter team home a few days early and delay the the summer team.