Recently a colleague asked how far can I look into the Universe with my amateur telescope (i.e. by the eye, not by photography). I found a (German) source saying that the brightest quasar, 3C 273 (https://en.wikipedia.org/wiki/3C_273) is the most distant object which can be observed with a good amateur telescope. Its distance is about 2.4 billion light-years. This is a fact which can be nicely used in popularizing astronomy. However, an object with a magnitude of nearly 13 ist not easy to be found and to be seen. Does anyone have experience to look at this quasar, and under which conditions?
Hi Wolfgang -
Here's a better answer than any I could give (since I've never tried to see it):
https://www.skyandtelescope.com/observing/12-quasars-for-spring-evenings/
All the best,
Peter
Thank you very much, Peter, for the link to this S&T paper. It seems to be very helpful, and I will try to find 3C 273 in a clear night with my 6-inch. However, the sky at Potsdam may be not dark enough, although we live near to the city boundary.
Wolfgang:
We often view this object at our public observatory, located on the edge of a town of ~50k population. Luckily, there are several foreground stars of similar or brighter magnitude in the field which make it relatively easy to locate. It appears star-like with a barely-detectable bluish tint.
That being said, we are using a 0.6-m telescope on a high-precision mount, so locating the field is very easy for us. Magnitude 12.9 is going to be considerably more difficult with a 6-inch aperture, especially if you don't have pristine, dark skies. If you are using a go-to mount, be aware that very few of the catalogs in such mounts' databases include 3C objects, so you'll either have to put in its celestial coordinates, or find a catalog which includes it under a different name (e.g. it is found in the Principal Galaxies Catalog as PGC 41121).
Finally, 3C273 reaches its apex at the end of astronomical twilight right around mid-May, so that's the best time to look to minimize atmospheric extinction (or earlier in the year if you're willing to stay up later to look.
Best of luck,
Chris Anderson, Coordinator
Centennial Observatory
College of Southern Idaho
Thank you, Chris, for sharing your experience in observing 3C273. I am afraid the observing conditions at Potsdam near Berlin with a relatively bright sky will not allow to find this object with my 6-inch reflector. However, I will propose this to the people who do public observations with the historic Great Refractor (1899) of the former Potsdam Astrophysical Observatory (double refractor, apertures 50/80 cm, one of the largest refractors in the world, see https://www.aip.de/grosser_refraktor/refengl.html for information in English). The location in a forest gives a darker sky than in the city. Although the view of 3C273 may not be so spectacular, it can be impressive for visitors to imagine how far the object is in space (and time).
Best regards,
Wolfgang
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