Orwell Astronomical Society (Ipswich)

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Double Quasar, QSO0957+56, 17-18 April 2018

A gravitational lens is said to occur when light from a distant object is bent by the mass of an intervening object so as to form multiple images of the former. In 1979, the double quasar, QSO0957+561, was the first example found of such lensing involving quasars. It is thought to consist of a very distant quasar which appears as two separate images due to gravitational lensing associated with an intervening galaxy. (The intervening galaxy is designated YGKOW G1.)

I imaged the object on 17-18 April 2018, using a Celestron EdgeHD 200 mm Schmidt-Cassegrain telescope with SBIG 8300 camera. One image of the quasar is clearly visible but, in my amateur equipment, the other is coincident with the intervening galaxy. A bigger scope and clearer skies are necessary to see both separately! In the inset image, the quasars appear at approximately magnitude 17 and the two stars at approximately magnitude 19.


Nigel Evans