Tuesday, 19 December 2017

PuWe1: Mission Impossible?

There are certain objects which tickle the imagination. You know that they're supposed to be virtually impossible to see with any amateur telescope, and yet the temptation's too strong. No matter how cold it is; no matter having to look for it for over an hour, you simply give in to this nagging crave in your chest and you point your telescope towards a remote corner of the obscure constellation of Lynx. There, in 1980, two Austrian astronomers called Purgathofer and Weinberger, discovered an extremely large, ethereal planetary nebula. It appeared so faint on their original photographic plates that they were unable to present it for printing along with the report of their discovery. Nowadays it has become a challenging object for skilled photographers who manage to capture its delicate structures after many hours of exposure time.

With its extremely low surface brightness of 23.7 mag/arcsec², it has always been deemed impossible for visual observations. But, as loyal readers of my blog will know, impossible is my middle name. What's more, I've got just the perfect instrument for large and extremely faint objects at my disposal. A binoscope effectively collects the same amount of light as a telescope 1,42 times its diameter, but... it offers that amount of light at a much lower magnification. I won't bother you with the technical explanation of all this, but suffice to say that the lower magnification allows to concentrate the frail light of the object on a smaller surface. In other words, you see it more clearly. How clearly? Well, don't get overexcited. After having stared at the right spot for at least fifteen minutes, I daresay that I did see "something". Yes, there was a broken circle of extremely faint nebulosity. It must be the faintest and most difficult object I've ever observed, even more so than oddities like ARO215. Yet, that's exactly the thrill that we faint-fuzzies lovers get from it. You know that it's on the edge of impossible. You're freezing, your limbs are giving in, your eyes are having difficulties to focus. But then... suddenly... that extremely faint arc reveals itself. And it was all worth it.

PuWe1 is one of the nearest planetary nebulae, its distance estimated at under 1,200 light-years. As you might have guessed, it's also very old and has extended over 6 light-years across in the last 20,000 years. Let's enjoy the show while we still can, because it won't be long before this nebula will be gone forever.

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