Q0957+651 - Gravitationally lensed Quasar

[lukebl]

The Twin Quasar Q0957+651 is an amazing object in Ursa Major, and surprisingly easy to capture. The first discovered example of gravitational lensing as theorised by Einstein.

It's apparently 8.7 Billion Light Years away (174 times more distant than the galaxy NGC3079 in this pic), and the gravitational lensing effect caused by an intervening (unseen) galaxy results in the light taking two paths either side. The single quasar thus appears as two separate points of light, separated by 6 arcseconds. The A component has a magnitude of 16.7 and the B component 16.5. There is a 417 time lag between the two images as one of them has a longer light path!

Captured over three nights with an Atik 383L+, 250mm f/4.8 Newt. 52 x 300s exposures luminance, 18 x 300s R & B binned 2x, synthetic green channel, 12 x 600s HA binned 2x

Edited March 25, 2022 by lukebl

[Peter Reader]

How did we identify this rather than thinking its just 2 very close stars?

[Trevor N]

That’s brilliant Luke. Intrigued with that. Trevor 

[City9Town0]

I'd seen this mentioned a while ago. I tried this with my ED80 DSPRO and 450D a few weeks ago... You have me well beaten. 417 days time lag... Quite a crop attached. Fifty exposures at 120 seconds. 800ISO.

Edited March 25, 2022 by City9Town0

[lukebl]

37 minutes ago, Peter Reader said:

How did we identify this rather than thinking its just 2 very close stars?

I asked myself the same question! Surely ‘they’ can’t be checking the redshift of every object in the sky?

[BrokeAstronomer]

5 hours ago, lukebl said:

I asked myself the same question! Surely ‘they’ can’t be checking the redshift of every object in the sky?

Oh man, astronomers love to acquire spectra. It is one of, if not the best way to learn about an object. It's chemical composition, temperature, radial velocity, redshift, rotation ..we can even learn about the composition of gas clouds along the line-of-sight to a distant object. Once we have an object's spectrum, we compare it to a theoretical spectrum at rest and use the Doppler equation to determine it's redshift. It sounds absurd, but if an object has been identified, there's a good chance it's spectrum was acquired and someone estimated it's redshift. P.S. I'm new here and I like to ramble.

[wimvb]

On 25/03/2022 at 21:17, lukebl said:

I asked myself the same question! Surely ‘they’ can’t be checking the redshift of every object in the sky?

 

On 26/03/2022 at 03:08, BrokeAstronomer said:

Oh man, astronomers love to acquire spectra. It is one of, if not the best way to learn about an object. It's chemical composition, temperature, radial velocity, redshift, rotation ..we can even learn about the composition of gas clouds along the line-of-sight to a distant object. Once we have an object's spectrum, we compare it to a theoretical spectrum at rest and use the Doppler equation to determine it's redshift. It sounds absurd, but if an object has been identified, there's a good chance it's spectrum was acquired and someone estimated it's redshift. P.S. I'm new here and I like to ramble.

Quite so. A lot of published research is based on sky surveys like SDSS and Gaia, zapping away in space, collecting spectra of almost anything up there.

https://en.wikipedia.org/wiki/Gaia_(spacecraft)#Scientific_instruments