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Gamma Delphini and . . .

Gamma Delphini
RA: 20h 47m Dec: +16°07′
Mag: 4.4, 5.0 Sep: 9.1″ PA: 266°
Distance: 100 ly
Spectral type: K, F

Should we call this the “Summer Albireo?” Only joking, but we have a spring, winter, and fall Albireo, so why not a “summer” one – well, because Albireo is the Summer Albireo – and, of course, really not very far west of  γ (Gamma) Delphini. But oh my, this is a little beauty with a surprise (for me) bonus!

I was just prowling around the other night under rather nice conditions. Well, the sky was nice. I was feeling the impact of sleep deprivation – too much of a good thing. I had been trying to put the Towa 339 into collimation with no success, so I grabbed my smallest scope, the 50mm Tasco 6TE5, sat down in a comfortable chair, and did some roaming among the familiar stars of summer  – starting with Albireo, my all-time favorite double because it’s the first one I remember seeing the colors of – a vivid blue and gold. Looked great in my 4-inch Criterion reflector back in 1963, and in a fit  of sophomoric euphoria I penned a poem that has long since been lost (thankfully), but I remember calling Albireo the “blue and gold mistake.” Don’t know why I called it a “mistake” – sounded cool at the time, I guess! I’m much older and maybe a tad wiser now, and I know that Albireo is extremely wide apart (35″) and an easy split in any scope.

Sorry for the rambling, but that’s the mood I was in this night and I also recalled that one of the stars in the delicate little constellation of the Dolphin was also a fairly easy split – I just wasn’t sure which one.  So I went for the one that was farthest north – what I think of as the Dolphin’s nose – and at 19X I wasn’t getting a split, but it was hard to get a real sharp focus. So I went up to 35X and I was sure I had a split, but I didn’t linger. I went immediately to 59X using a 10.2mm  Televue Plossl and bingo! Now that’s real nice. Makes sense, too. While Albireo can look sweet at 20X, the 10 second separation of γ Delphini demands more – but the result is what I saw as a tangerine and bluish-green stars. In fact the secondary reminded me of the warm, clear green-blue waters you sometimes see dolphins playing in – well, I see them playing in such waters in the movies. Maybe you’re more lucky and have seen the real thing.

In “Turn Left at Orion” – I checked that when I went to write this report – they list the colors as “orange” and “lime.” I accept that. They also call it “one of the prettier pairs in the sky.” Yep! And it turns out I missed a second double that may have been in the same field of view, but  is fainter and closer. I’ll blame this first on my ignorance, then  on the 50mm which may not be able to split this second pair. But it gives me a reason to revisit γ soon, and with a  60mm next time.

This second pair is Struve 2725. The stars are 7.2 and 8.3 with a separation of 5.7 degrees. Sissy Haas – “double stars for small telescopes” – also says it’s in the same field as γ and lists the separation as 6.1″ noting that it looks like a “smaller duplicate of Gamma.” Hmmm . .. guess this is a good argument for planning observing sessions rather than just prowling around 😉

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One Response

  1. I had a look at this pair back on August 1 and got the theta & rho correct but not the colors. I got a “yellow/brown” primary and a pure “yellow/white” companion. I’ll have to take another look before it sets in the west quite soon. The primary is known as a “main sequence yellow giant” and the companion a “supergiant.” At 90X with my 1 1/4″ Plossl 26 mm, (Celestron 925), I also got STF 2725 AB in the same field of view w/ 8 other field stars. I’d like to post my sketch, but don’t see a way to do that.

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