Is it possible to identify the first direct observation of the gravitational lensing?

What object was lensed, and where did the energy detected fall on the electromagnetic spectrum?

  • $\begingroup$ Your post is about 80% nonsense and rambling that does nothing to encourage people to read, let alone answer, your question. Please cut out the waste and trim it down to the simple question you want answered. And, yes, seriously, it is possible to limit your post to one question and we do seriously expect that done unless it's unavoidable. $\endgroup$ – StephenG Jun 12 at 20:28
  • $\begingroup$ That's why I bolded the actual questions! Also, one man's rambling nonsense is another man's multilayered refusal to take himself (or anything else for that matter) too seriously. Alas, I'm certainly not interested in exhibiting any behavior which conflicts with an existing culture which was likely deliberately cultivated over time. I've been on the other side of that issue, and won't be that guy. I'll de-fluff the post and try to consolidate the questions into a single concise version. It probably won't shock you to hear that this is not my first finger-wag on a Stack-Exchange forum. Oh well. $\endgroup$ – BigNutz Jun 12 at 22:30
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    $\begingroup$ +1 for the edit! I've fine-tuned the format. Stack Exchange is open to the entire internet and what keeps it running so smoothly is a shared concern of maintaining a certain minimum requirement for what a Stack Exchange question should be. It's certainly more than okay to be modest and not take ones self too seriously, but if it doesn't add to the clarity of the question then it doesn't belong in a Stack Exchange question post. $\endgroup$ – uhoh Jun 12 at 23:37
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    $\begingroup$ I don't know if this qualifies as lensing or if we should just call it deflection: en.wikipedia.org/wiki/Eddington_experiment There are a few different kinds of gravitational lensing effects and each may have a first observation. Wikipedia says It was not until 1979 that the first gravitational lens would be discovered. for example, and Microlensing by an isolated object was first detected in 1989 $\endgroup$ – uhoh Jun 12 at 23:40
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    $\begingroup$ This is a couple of great examples. The sheer scale and distances involved make me giddy! $\endgroup$ – BigNutz Jun 12 at 23:43

The first identified gravitationally lensed object is known as the Twin Quasar.

The Twin Quasar (also known as Twin QSO, Double Quasar, SBS 0957+561, TXS 0957+561, Q0957+561 or QSO 0957+561 A/B), was discovered in 1979 and was the first identified gravitationally lensed object. It is a quasar that appears as two images, a result from gravitational lensing caused by the galaxy YGKOW G1 that is located in the line of sight between Earth and the quasar.

You can see it right in the middle of this picture:

Twin Quasar

The Twin Quasar's two images are separated by 6 arcseconds. Both images have an apparent magnitude of 17, with the A component having 16.7 and the B component having 16.5. There is a 417 ± 3-day time lag between the two images.

The quasars QSO 0957+561A/B were discovered in early 1979 by an Anglo-American team around Dennis Walsh, Robert Carswell and Ray Weyman, with the aid of the 2.1 m Telescope at Kitt Peak National Observatory in Arizona, United States.


Critics however identified a difference in appearance between the two quasars in radio frequency images. In mid 1979 a team led by David Roberts at the VLA (Very Large Array) near Socorro, New Mexico/USA discovered a relativistic jet emerging from quasar A with no corresponding equivalent in quasar B. Furthermore, the distance between the two images, 6 arcseconds, was too great to have been produced by the gravitational effect of the galaxy G1, a galaxy identified near quasar B.

Young et al. discovered that galaxy G1 is part of a galaxy cluster which increases the gravitational deflection and can explain the observed distance between the images. Finally, a team led by Marc V. Gorenstein observed essentially identical relativistic jets on very small scales from both A and B in 1983 using VLBI (Very Long Baseline Interferometry). The difference between the large-scale radio images is attributed to the special geometry needed for gravitational lensing, which is satisfied by the quasar but not by all of the extended jet emission seen by the VLA near image A.

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