How soon could extrasolar planets have been discovered? Options

[Mongo]

Extrasolar pulsar planets were first discovered in 1992, and the first planets around main-sequence stars in 1995. However, it seems clear that main-sequence exoplanets could have been found much earlier, except for the fact that nobody actually looked for them in a way that would have succeeded.

The standard assumption was that all, or almost all, planetary systems followed the architecture of our own system -- a few terrestrial planets at distances ranging from a few tenths of an AU to a few AUs, with larger gas- and ice-giants further out. This would result in systems that are basically impossible to detect with the technology of the time, except perhaps for long-term (years to decades) astrometric studies of nearby dwarf stars. It was known that planetary transits would be easily detectable, but they were thought to be so unlikely due to the geometry, as well as being infrequent in the few existing transiting systems, that they were not worth the resources spent searching for them. Radial velocity searches were considered to be out of the question, with stellar RV shifts ranging up to a few m/s at best, well below the best sensitivity of the spectroscopes of the time.

In fact, "Hot Jupiters" are common, with RV swings measured in the tens or hundreds of m/s, and transiting planets are so common and easy to spot that many current search programs use telescopes no larger than typical amateur telescopes. Today's detectors are better, of course, but that could be compensated for with a slightly larger telescope.

I assume that a planet search program consisting of an all-sky transit search with one or more 30cm-class telescopes would produce several dozen candidates (with at least three observed transits each) orbiting fairly visually bright stars within a few months. Each of those would be examined spectroscopically, and each would be soon found to have RV swings of 50-200 m/s or more. With the existing spectroscopic classification of the primary stars, this would result in fairly accurate masses and radii for each of these planets, as well as expected daytime temperatures. It would be easy to calculate the frequency of "Hot Jupiters" around main-sequence stars (around 1%), and the "inflated Jupiter" effect should be apparent in the data.

So assuming that some astronomer manages to obtain funding and telescope time to conduct such a program, when was the astronomical photometer and spectroscope technology advanced enough for this to have succeeded? The 1960s? 1970s? Surely by the 1980s, at the latest, which seems very late to me.

[Hungry4info]

Stebbins (1910) was able to get photometric errors on the order of ± 0.006 mag, detecting the secondary eclipse of Algol for the first time. HD 189733 b has a 0.03 magnitude transit depth. So I suspect we've had the technology to detect transiting hot Jupiters for around a hundred years now. Getting a mass estimate would have been much harder. NGC3314's great post covers that part well enough.