3C 273, Or, Why I Stay Up All Night
When a non-astronomer sees my telescope for the first time, I'm usually asked two questions, "How powerful is it?", and "How far can you see?" I end up trying to explain that astronomers are more interested in things like light gathering ability, resolution, optical quality, yada, yada, yada, but more often than not, the look on their face tells me the answer is about as satisfying as eating at a five-parsley restaurant. The nuances and subtleties are great, but "WHERE'S THE BEEF?"
The reason I bring this up is that this time of year, the spring, there is a well-situated object in the constellation Virgo that will answer at least one of the questions. It is a quasar called 3C 273, and at 2.6-3 billion light years away, it is generally regarded as being the most distant object, by a wide margin, visible with the average amateur telescope. The name 3C 273 designates that it is the 273rd object in the third Cambridge Catalogue of Radio Sources.
3C 273 shines at about magnitude 12.8, and to be visible at this distance it must be one of the brightest objects in the universe. It is estimated to be thirty trillion times brighter than the sun and 100 times brighter than a large galaxy. I'm pretty sure it's brighter than my neighbor's yard light. At magnitude 12.8 it's easier to see than Pluto at magnitude 14. It's located about 3.5 degrees NE of Eta Virginis and 3 degrees SE of the galaxy M61. A detailed finder chart can be found on page 2101 of "Burnham's Celestial Handbook" and various places on the Internet. It is shown on SkyAtlas 2000, but the scale is too coarse on this atlas to be of much use. 3C 273 is just a faint point of light, so it looks like a small, bluish star. In order to find it you need a chart that shows stars at least as faint as magnitude 13 or 14. Most of the software for the better planetarium programs go down to mag 15.
Theoretically 3C 273 should be visible in a 6" scope, but practically you'd need at least 8", and 10" would be better. On a clear, moonless night, it should be fairly easy in the club's 16" scope. Once the moon goes down, I'm going to seriously try to find it so the next time I'm asked, "How far can you see?" I'll be able to confidently say, "Oh, about
2.6 billion light years". Now, about the question of, "How powerful is it?" That's easy. On a clear, dark, steady night, powerful enough to keep me up most of the night. Doug Tanaka