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Old 13-09-2018, 10:20 AM
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The Observologist

ngcles is offline
Join Date: Dec 2006
Location: Billimari, NSW Central West
Posts: 1,629
Seeing Fritz Zwicky's ring (aka the Cartwheel Galaxy)

Hi All,

Just wanted to share one observation with you from an excellent night at home in the NSW Central West near Billimari. Very nice conditions, SQML reading was 21.88 at 11pm just before I made this observation with my new 63.5 cm f/5 Newtonian: Brontes.

After checking out the gorgeous near edge-on spiral NGC 134 in Sculptor, I remembered that Zwicky's Ring (aka the Cartwheel Galaxy or ESO 350-40) was only a few medium-powered fields away and not having observed it for almost two decades, decided to trip on over to see what could be seen.

I could spend a bit of time rummaging through a thesaurus for a short list of alternate adjectives but off the cuff, I'm going to go with: astounded. Seriously, I thought I'd died and gone to heaven but I guess I must be alive as here I am reporting the observation.

For those who aren't familiar (I'll forgive you if you aren't), the image depicts Zwicky's Ring. I had glimpsed it once before with my old 31cm telescope -- just barely detected it as a spot of fleeting gossamer but the view tonight was something for which I was not prepared.

At x260 and then x346, what I saw was ... a wheel. Seriously, I couldn't believe my eyes! Yes, it's still a faint galaxy but there it was: A faint & low surface brightness, slightly oval, closed ring, seeming about 1.25 arc minutes diameter with a darker centre (though not completely dark).

I spent about 15 minutes at the eyepiece and what else should I see? A faint star (the one on the right-hand edge of the ring in the photo) (that is roughly 17th magnitude BTW), but **additionally** (I counted 'em) five other (fainter) star-like points embedded in the rim of the thin doughnut -- four in the southern part of the ring and one in the north. In the attached photo (which is a Hubble Space Telescope classic), North is to the upper left and East is upper right, the four star-like points ran down the right-hand side of the ring below the star (this yellowish star is a foreground star in our galaxy) while the other was embedded in the left-side nearer the other two galaxies.

Oh, didn't I mention those other two galaxies (PGC 2249 & 2252) before? I could see both of them too as tiny spots of ephemeral mist. Those star-like points I saw embedded within the outward propagating ring of star formation at the edge of Zwicky's Ring are in reality, gargantuan star factories furiously pumping-out masses of mega and hyper stars.


All this observed from my Billimari front paddock ... front row but a mere 500 million light-years distance.

As I said: Astounded -- also delighted. Life achievement unlocked -- a hard-core deep sky observer's moment of nirvana!


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