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A Slice of Aquiline Pi: Pi (π) Aquilae (Σ 2583)

As summer twilight surrenders to early August darkness at about 10PM in my mid-northern latitude, high up in the southeastern sky and wedged up against the eastern edge of the Milky Way, there’s a little orangish dot of sixth magnitude light flickering behind the 2.7 magnitude glow of Gamma (γ) Aquilae, which  of course we all know as Tarazed.  😉

Altair, Tarazed, and Pi (π)– all nestled up high against the eastern edge of the Milky Way. (Stellarium screen image with labels added, click for a larger view)

And I heard it calling to me  ……………

Actually, the first time I heard the Pi (π) call was when I read Neil English’s Cloudy Nights post on it.   Neil scoped it out with a four inch refractor and found it a difficult one to crack at that aperture.  It’s close separation of 1.4″ had me hesitating since that’s normally a bit beyond what my local atmospheric conditions permit.  On the other hand, with only half a magnitude of difference between the two stars, it struck me as having possibilities — although their relatively dim, non-Porrima like magnitudes had me a bit concerned.

But 10PM is well past desert time, so it seemed that a slice of this Pi (π) might make a delicious Star Splitting snack.

First, the location:

Pi sits a bit more than a degree to the north of Tarazed — you should be able to easily see it in a 6×30 or 8×50 finder paired with 6.5 magnituded HIP 97489 just to the southeast. If you look closely at the chart, you’ll see that Pi (π) forms a triangle with Tarazed and Omicron (ο) Aquilae – and with Tarazed and Chi (χ) – and with Omicron (ο) and Phi (φ) – for a total of three triangles in the sky! (Stellarium screen image with labels added, click for a larger view)

And then the numbers:

Pi (π) Aquilae  (Σ 2583)   (H I 92)        HIP: 97473    SAO: 105282
RA: 19h 48.7m   Dec: +11° 49′
Magnitudes   AB: 6.34, 6.75     AC: 6.34, 12.90
Separation:   AB: 1.50″            AC: 36.10″
Position Angle     AB: 103°  (WDS 2012)     AC: 297°  (WDS 2007)
Distance: 570 Light Years
Spectral Classification: A3, F9  (A and B)

My first attempt was with a four inch f10 Celestron refractor, but luck was pretty much out to lunch that night. I worked up to my magical 7.5mm Celestron Plössl (133x), which provided the barest hint of what might be possible, then gave a seldom used 5mm UO Ortho (200x) a chance to get out of its box — sorry, back to the box — and then tried a 2x Barlow with the 7.5mm Plössl (267x).  The entire time I was magnifying more moisture than photons, the seeing was about a II, and the transparency was right there with it.  It was almost impossible to see past the glare caused by the moisture, and fighting the hopping fueled by the poor seeing was frustrating as well as futile.

What I could actually see when my eyes were able to lock on to something resembling an image was a very faint and fuzzy something that looked like a peanut — but even that was elusive. The color was beautiful, though, kind of a light orange with a strong bit of yellow thrown in there somewhere.

Neil’s first attempt was about like mine, but when I read of his success the second time with his four inch f/15 refractor, I couldn’t resist seeing if I could match it with mine.  So the following night out came the Antares 105/1500, which actually works out to f/14.3

Looking for some kind of edge, I decided to try before the sky was completely dark.  At 9:30 PM, I aimed the long white tube of the Antares scope at Pi (π) in the sky and licked my lips.  I knew success was lurking in an eyepiece — the real question was whether or not it was one I owned.   On my first attempt, with a 15m TV Plössl (100x), I was rewarded with an image that looked like an unfocused football.  Realizing the seeing might improve later in the night, I set the Pi (π) aside for a few hours.

It was about 2 AM when the skies became more stable, so back I went again with my taste buds quivering.   This time I smelled victory — I could even hear a fork scraping the last few bits of Pi (π) from the plate.

A 10mm Radian and its 150x produced an elongated image in the eyepiece, which was my first real glimmer of hope. I swapped it for the 7.5mm Celestron Plössl and its 200x, and started to see enough vibration to make it demanding and difficult. I thought I could see a peanut shape a couple of times, but the seeing was starting to slip south again, back to the football smeared swell.

But what the heck — no pain, no gain  ………….  so I went for the pain.

A 4mm Astro-Tech Plössl and 375x.

Geeeeeeeeeeeeezzzzz that stung. The image was smeared from one side of the eyepiece to the other. I leaned back in my chair to give my eyes a chance to recover, muttered some unflattering things about the jet stream, leaned forward and looked again, and saw a slight improvement — very slight, in fact, but enough to have a fighting chance for a few random micro-seconds.

When I could eke out something resembling an image, I saw two distorted discs touching each other, bouncing back and forth in their linked dance at half the speed of light. What little bit of focus I could wring out of that image was very fuzzy and right at the edge of what my mental material was able to wrestle into something resembling a pair of stars.

Neil described that kind of view as surreal — I’ll call it un-real.  It was two throbbing orangish smears of light trying to be round and stuck to each other like siamese twins. And bouncing around as they were against a background of black sky illuminated by a flickering orange glow, I was reminded of a forest fire burning at night in the distant darkness.

Maybe, just maybe, there was a sliver of black between them, but I really wouldn’t want to swear to it — the image just wouldn’t hold still for enough micro-moments to get a sharp mental snapshot of it. It’s easy in that situation for the imagination to take over and see what it wants to see ………. or it could have been that my eyes were just tossing up a quick illusion because they couldn’t take any more, and were trying to lure me into giving it up so they could rest.

Once again, the sweet smell of success and the tantalizing taste of Tarazed flavored Pi (π) had slipped just out of reach.

But  —-  like Charlie Brown lured by Lucy holding the football, I had to try again —  with an extra inch of aperture.

So promptly at 10 PM the next night, I pointed my five inch Meade refractor at Pi (π), slipped a 10mm Radian (118x) into the diagonal, and just as on the previous two nights, I saw some promise in the eyepiece.  And since it had almost become habitual by now, I swapped the Radian for the 7.5mm Celestron Plössl (157x), and could see that if success was lurking in an eyepiece, this was clearly going to be its night.  The Pi (π) was just begging to be sliced now.

And being a cooperative type — not to mention hungry — I swapped in a 6mm Astro-Tech Plössl (197x)  ……………

………….  and there it was. Two very distinct yellow-orange globes of light, almost touching. I don’t know which emotion was stronger — the surprise, or my awe at the beauty of the image.

I tried a 4mm AT Plössl (295x), which put more space between the two stars, but found I was fighting the focal demons again, so I went back to the 6mm AT. The AR-5 was mounted on an un-driven alt-az mount, which meant Pi (π) was zipping through the Plössl’s narrow field of view like greased lightning.   Out with the AT and in with a 6mm Radian, giving me a wider and more comfortable field of view, as well as a decent interval of time to feast my eyes on these two slices of Pi (π).

Now close your eyes and try to picture this:

The background sky is jet black, most of the orange glow that was so pervasive in the two four inch scopes is absent, and at the center of the field of view are two pinpoints of light, two very distinct and very small orange globes, one of them just slightly brighter than the other.  To describe this view as stunning does not even come close to conveying the absorbing beauty that saturated my hungry eyes.

A slice of visual Pi (π) to aid in conjuring up a mental image of what the view was like. (East and west reversed to match the refractor view, click for a much better view)

A slice of visual Pi (π) to aid in conjuring up a mental image of what the view was like. (East and west reversed to match the refractor view, click for a much better view)

I watched those luscious little stellar points of orange light as they drifted through the black void in the eyepiece, turned the slow motion control knobs to re-position them when they reached the edge of the field, watched again, re-positioned again, watched some more, re-positioned some more   ———   I did that for thirty minutes.

Other than re-positioning the scope, I didn’t budge.  I hardly breathed.

Time stood still.

What I should have done was go get one of the four inch scopes, but the thought never occurred to me.   The seeing was certainly four (IV) on a scale of five (V), so I missed a chance there to let the four inch scopes perform at their optical limits.  I think they’ve forgiven me, but they haven’t forgotten.

But what a difference an inch of aperture makes on a good night!  What I had noticed in the two four inch scopes was how fast I ran out of light when I increased the magnification to the insane levels I need to get a split.  Even if I had been able to slice Pi (π) with either of those scopes, I suspect the faint image would have been a whole lot less than satisfying.  The extra inch of light gathering ability that the AR-5 provided made a split at less magnification possible, meaning loss of light never became an issue.

So  ………  what if I was to add yet another inch of aperture …………………..

I couldn’t resist seeing what the six inch f10 could do with two slices of orange Pi (π), so a couple of nights later I hauled it out, set it up, pointed once more at Pi (π) in the sky, and took a seat.  And I was simply star-struck to see both pieces of Pi (π) as two distinct, touching globes, at 109x in a 14mm Radian.  They were barely split — hairline split describes it well — at 127x in a 12mm Radian, which I found fascinating.  I needed about 175x in the AR-5 to achieve that, so the extra inch was paying off once again.

But real magic was found at 152x in a 10mm Radian.  This time I was using a driven equatorial mount, so I didn’t have to move.  I could just sit there and stare  …..  and absorb  …….  and salivate   ………..   at the sight of those fantastic little orange gems of delightful light as they stared back at me from a curtain of black velvet decorated with a scattering of star dust.

And I did sit there and stare.

And I didn’t move, either.

Except to sip a cup of tea to wash down the best darn orange Pi (π) I’ve ever eyed.

Clear Skies!  😎

(WDS data updated 7/17/2013)

And here's another view in a five inch refractor, only this time at higher magnification and a longer focal length.  (East & west reversed, click for a larger view).

And here’s another view in a five inch refractor, only this time at higher magnification and a longer focal length.  Notice how the background stars are barely visible in this smaller field of view — you have to click on the sketch to enlarge it in order to see them!  If you look closely, you can see 12.90 magnitude “C” just to the west of the primary and secondary.  (East & west reversed).

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One Response

  1. I keep coming back to Pi Aquilae again and again and again, just like a moth to a flame.

    The intriguing thing about this pair of stars is how difficult it is to get some noticeable space between them. That’s mainly because the darn things are so dim. At magnitudes of 6.34 and 6.75, there’s not a lot of light to work with at high magnifications, and the diameter of the points of light you’re working with is noticeably less than what it would be in a pair of fourth magnitudes stars, such as Porrima.

    When you view Pi Aql at lower magnifications and in a wider field, you can’t help but notice it’s surrounded by a rectangular area almost devoid of stars, although there are hints of faint points of light visible if you look closely. Outside that rectangle, there are countless field stars, which provides a contrast very pleasing to the eyes.

    Wondering what could be seen in that almost void of blackness rectangulating around Pi, I pointed my five inch D&G f/15 refractor at it using an 8mm eyepiece yielding 238x (I’ve added the sketch at the end of the post). What I saw was a very eerie field of faint stars, all with fleeting phantom-like appearances — they tend to wink in and out of view, depending on where they strike your averted vision receptors.

    Even at 238x, though, I still couldn’t get those two diminutive points of diameter-deprived light to separate significantly. The latest WDS separation for the pair is now 1.5″ (2012), a slight change from the earlier 1.4″. But who knows what the decimals lurking behind those numbers are — it may be the difference between 1.44″ and 1.46″. Whatever the case, it sure as heck isn’t enough to make any noticeable difference!

    John

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