This is my probably impossible mission to capture an image of the so-called Einstein Cross.
But, at least, I found the Galaxy which works as a gravitational lense of a much more distant quasar Quasar : QSO2237+0305
( below red marker. I carefully checked against the Simbad database)
RA : 22h40m30.3s DE : 03°21'31"
This Galaxy, PGC +69457, has a brightness magnitude of 14.5 and is some 400 million light years away .
The actual "Einstein Cross" from that Quasar would only shine as 17.5 magnitude four star constellation around the gravitational lense galaxy core.
If I could separate that quasar light at all, this would be light as old as 8 billion lightyears away !!!
( current estimates of the age of our Universe is 13.8 billion years )
Remark :
Is it possible at all ?
The 12" Dobson has a theoretical angular resolution of 0.32".
The lensed quasar light beams are 1.4" distant to the gravitational lens galaxy core.
So far, so good ..
But the biggest problem is the required focal length (FL) to resolve the Einstein cross
at a given CCD chip. ( Atik 383L CCD : KAF-8300 = 5.4 micrometer )
Thumb rule : FL = D (305 mm) x 5 x CCD Pixel (5.4 micron) = 8235 mm
Any attempt to use Barlow lenses to come from 1500 mm to 8000 mm FL will fail.
(Losing too much light and precise tracking at this FL would be almost impossible)
P.S. Feb. 2021
the factor 5 in the thumb rule may be too high
The Einstein Cross was resolved by a 22" telescope f/8 560 mm and SBIG ST8XME at 9 micron.
(
https://ocastronomers.org/wp-content/uploads/2018/12/Pcg69457_Einstein_Cross.jpg)
which results to 560 * 5 * 9 = 25200 mm focal length : impossible
if we use factor 1 then f = 5040, which is close to the 4480 native focal length of this Telescope
cheers
Wanni
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