The French Observatory

Six European countries spend seven years looking for a southern sky and build a working observatory on a Zeekoegat sheep farm, then leave for Chile. The third time the outside world came to this one farm for something it could not get elsewhere - after the gold and the fossils - and the third time the answer was nearly.

Zeekoegat, 1954–1996

There is a sign on a gravel road west of the N12 that reads French Observatory. It is faded and it is not explained, and most people who pass it do not slow down. Behind it is the reason six European countries spent seven years looking at the sky over a Karoo sheep farm, and then left for Chile.

Why here

The problem was straightforward and it was not about South Africa. By 1954 European astronomy could see only half of what it wanted to. The Magellanic Clouds, the centre of our own galaxy, most of the interesting sky, all of it sits south, and there was no European instrument south of the equator worth the name.

On 26 January 1954 astronomers from six countries met at Leiden to do something about it: Belgium, France, Germany, the Netherlands, Sweden and Great Britain. Britain pulled out in October 1956 to pursue a Commonwealth telescope in Australia instead. The rest became the European Southern Observatory.

South Africa was the obvious place and everybody assumed it from the start. It already had Harvard's Boyden Station near Bloemfontein, Leiden's southern station at Johannesburg and later at Hartebeespoort, the Radcliffe near Pretoria, and Britain's Royal Observatory at the Cape. But every one of those sat near a city, and a city is exactly what a telescope cannot have. ESO wanted its own ground, far from anybody's lights.

So they came looking for the emptiest, driest, stillest place they could find. Which is one way of describing the Koup.

Four young men off a ship

The first party sailed on the Zuiderkruis, the Southern Cross, in October 1955 and landed on 6 November: G. Courtès from France, J. Dommangel from Belgium, H. Elsässer from Germany and Ch. E. Heynekamp from the Netherlands. They started setting up pilot stations almost immediately.

They looked at Graaff-Reinet, at Beaufort West, at the Hantamsberg near Calvinia, at Laingsburg, at Willowmore, at the Rooiberg near Calitzdorp, at the Swartberg. After a three-month look the choice came down to two: the Nuweveld plateau about 35 km north-west of Beaufort West, and Zeekoegat.

The French team took Zeekoegat. The German-led team took the Nuweveld and stayed on Klawervlei. The first report went back to Europe in January 1956.

The dome

Construction started in 1958. What went up was a cylindrical building with a dome, and inside it a 40 cm objective-prism refractor, the Grand Prism Objectif, an exact copy of the instrument at Marseilles, used for measuring radial velocities. It was fully working by the middle of 1961. There were staff houses and an office. In time the German sites on the Nuweveld were closed, and by then it was clear that Zeekoegat had stopped being a test site and had become an observatory, returning real results.

Between July and September 1963 they ran the newly developed Siedentopf turbulent-cell technique here and at Flathill, a way of measuring the rapid temperature flickers in the air that blur a star, and it worked well.

The job needed a particular sort of person. Qualified astronomers did the bulk of it, but the final testing programme wanted staff who could improvise, fix things themselves and live for long stretches in rough conditions a long way from anyone. Somebody worked out that the job description fitted an ambitious Boy Scout, and two were duly sent from Holland. Both went on to permanent ESO careers in South America.

They also, being young and very far from home, began counting the donkeys visible from each station as a measure of how remote it was. This went into the reports. Eventually an edict arrived from Europe instructing them to leave the donkeys out.

The boy who found it

Around 1963 a ten-year-old named Eric Swanepoel was poking about in the veld while his father, a welder, worked for a company building the stretch of the N12 between Beaufort West and Klaarstroom. Their workshops and living quarters were about a kilometre from Zeekoegat.

He saw a rounded white building in the distance, unlike anything he had come across. His parents told him it was a sterrewag. That was not nearly enough for him, so he went and found out for himself that it had "a big, big telescope inside".

Then luck: in the little Zeekoegat store, he and his parents ran into a family friend from Aberdeen who happened to work at the observatory, and who invited them up. Eric got to see the telescope. He was not allowed to look through it. He was disappointed by the photographs, which were pictures of black dots. And he was entirely delighted when the friend offered to save him the stamps off all the foreign mail.

Fifty years later he went looking for what it had been, which is how a good deal of this is known at all.

Chile

In the end the sky over the Andes was better. Cerro Tololo had something like forty per cent more clear nights than Zeekoegat, and Chile's temperature swings were much smaller, which matters more than clear nights do, still air is what "good seeing" means. La Silla won. The Zeekoegat telescope was crated and shipped to South America. The South African project was finally decommissioned in 1996.

Adriaan Blaauw, who was in it from the beginning, wrote that the switch

did not pass without bewilderment to the young astronomers and their collaborators who worked in South Africa. Their disappointment was undeniable, and they could not help but ask whether their years of effort had been wasted.

He added that the disappointment gave way to the conviction that the decision had been right. Both things are usually true at once.

What it belongs to

It is tempting to file this as a curiosity. Europeans on a Karoo farm, briefly, then gone. It reads better as the third instance of the same thing.

Three times the outside world came to this one farm for something it could not get anywhere else, and each time the answer was nearly:

• Gold, in 1871 and again in 1891. Five hundred diggers, 1,042 claims and 504 ounces.

See S002.

• Fossils, through Roy Oosthuizen's museum on Zwartskraal, and this one actually came off,

because the ground genuinely did hold something world-class and a farmer with a good eye found it. See S004.

• Stars, from 1958 to the 1960s, and then Chile.

What all three have in common is that the Koup's emptiness is its asset. Nobody came here for the farming. They came because there is nothing in the way, no overburden on the fossil beds, no lights, no people. The same quality that made this a hard place to make a living made it worth a long journey three times over.

And the church that Frederick Simon Oosthuizen built in 1906, because a community had grown up on his farm and Prince Albert was too far to ride, is still standing while the dome is a shell and the diggings are pits in the veld. See S003.

Still open

• The exact site of the station. The sign survives and photographs from 1962 exist, but no

coordinate for it is held here and none has been pinned. It gets no map pin until it is fixed against a survey or an aerial photograph.

• Who owned Zeekoegat in 1958, and what were the terms? Somebody signed something to let ESO

build on it. That paper would put a family name into this story, which at present has none.

• Local names in the ESO records. The final testing programme relied on local

enthusiasts to gather meteorological data. Those would be Prince Albert and Klaarstroom people, and none of them is named in the cameo.

What this story is about

• set on Zeekoegate

Sources

Everything this story rests on, with a link to the original wherever one exists. Where a citation is incomplete it says so, an incomplete citation is a research gap, not a formatting problem. If your work is here and the credit is wrong or thin, please tell us and it will be fixed.

1. Rose Willis & Doreen Atkinson, "Zeekoegat: Explorations in the Koup Karoo" (2022) Karoo Development Foundation38pp cameoview it online →

Research notes

The research behind this page, kept separate from it: dated working notes, open questions, and what is not yet settled.