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Eta Persei

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#1 Asbytec

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Posted 22 November 2012 - 08:57 PM

Really having a hard time kicking off a double star campaign, mostly because Jupiter is taking so much time. Star hopping with a moon lit sky doesn't help. Plus a few other excuses, like not being familiar with the catalogs to cross reference stars and finding a nice tight, colorful pair.

Despite that, however, I do manage a few here and there. Usually the easy ones, like Eta Persei. Maybe those are the doubles a double star novice should start off with. Eta is quite nice, actually. The primary was school bus yellow and the companion seemed more Alice blue than white.

Wide separation and PA about 300. Apparently there is a third companion listed pretty far away. There are some stars in the field, but I had no idea which would be the third component. It might have been a brighter star NW outside the field shown.

Seeing was about 7 to 8/10 and just enough to disturb the first ring. Transparency was nearer to mag 3. Nice night, just lit by the moon.

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#2 RobDob

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Posted 22 November 2012 - 11:14 PM

Nice description and nice sketch! Need to check this one out...

#3 7331Peg

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Posted 23 November 2012 - 01:09 AM

Aw, how about a wider view -- you miss the real beauty of this star at 240x. I would agree with the Alice blue (how did Alice get dragged into this?), but I always see reddish-orange in the primary:

John :refractor:

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#4 Asbytec

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Posted 23 November 2012 - 05:07 AM

I dunno, "go ask Alice." :)

Actually, I am trying to use flowery colors, that one seemed appropriate and flowery and fresh. Robin egg blue is a bit worn out. Plus, it kind of fit my mood.

Yes, well, that is a fine star field. I did view at lower power, too, just sketched at high power. Old habit, I guess. Maybe it is nicer to include the "vista" view. The include a higher power inset. Great method, I like it.

Is there a reference for the magnitudes of the field stars? I wanted to get a feel for the limiting magnitude that night, and really most nights I observe.

Thank you for posting a great sketch.

#5 7331Peg

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Posted 23 November 2012 - 04:12 PM

Yes, "I think she'll know!" :lol:

Which reminds me, that's Orangutang Orange I saw in the primary. :grin:

I use MegaStar for magnitude references, although it doesn't always show all the field stars. But I don't think any of the planetarium programs ever do. I also have Sky Safari and Stellarium, and neither one really go deep enough -- although I believe you can load more stars into Stellarium than I have at the moment.

And you can always get the magnitudes for the companions from the WDS.

Here's the sketch again with some of the stars labeled. Looks like the faintest I went that night was a 12.9 magnitude star. I've gone to as dim as 14.5 with that six inch scope, but that's the limit from my moisture-laden coastal skies.


John :refractor:

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#6 Astrodj

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Posted 23 November 2012 - 06:59 PM

Great sketches guys! Eta Per has been a favorite of mine since '69. I have been neglecting this one so I must make amends.

#7 Asbytec

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Posted 23 November 2012 - 08:47 PM

John, super. Yes, I use Stellarium with stars down to 13.5. You're right, it does not show them all. Sometimes that makes identification difficult. My limiting magnitude on that night seemed to be about 11.4, that faint star just north was, eh, kind of tough. That was with a half lit moon halfway across the sky.

Once I ran across an image of the crab nebula that had some very faint stars listed. On that night, I was reaching down to about 14th, too, well dark adapted observing M1, etc. Other nights, 9th mag can be pretty dim. In fact, I think that 9.9 mag star shown SE was giving me trouble, too.

Thank you for replying. Oh, and no fair not showing the diffraction rings. One might think a 6" refractor is the best scope for doubles, or something. :lol:

DJ, thanks and please do observe your favorite. It's my first time seeing it. It's a nice one. One for the books.

#8 7331Peg

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Posted 24 November 2012 - 12:51 AM

Sorry about the diffraction rings -- I've haven't come up with a way to do that and still have it look realistic. It usually comes out looking like a couple of warped donuts.

What's deceptive about those sketches is actually that they don't show the glare around the primary -- and that can make it rather difficult at times to see the "C" companion, and even more so with regard to "D."

I'm using Microsoft's Paint program for the most part now, but am looking at trying something else soon. Adobe's Photo Shop would be the way to go if it wasn't so darned expensive.


John :refractor:

#9 Asbytec

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Posted 24 November 2012 - 02:01 AM

Na, no worries. I was just funnin' ya.

They are very nicely done. And 6" refractors are superb on doubles. Actually, I wasn't surprised you didn't include them, they might have been pretty faint. I kind of like the diffraction rings in my scope. Or don't mind them, anyway. :)

#10 7331Peg

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Posted 24 November 2012 - 02:28 PM

There's no question that diffraction rings are dazzling. I've been hypnotized right out of my chair more than once by them.

When that happens, just remember ........ "what the doormouse said!" :grin:


John :refractor:

#11 Asbytec

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Posted 24 November 2012 - 03:57 PM

:lol:

Sometime in the 80's, I happened upon Airplane (then Starship, I believe) at a free concert in DC performing some of their renown hits and signature sound. They just really took it back to a special era the wife and kids would not understand.

Cheers

#12 fred1871

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Posted 24 November 2012 - 10:26 PM

Very nice drawing, John. From where I am, well south of the equator, Eta Persei is not observable, but in the mid-90s I spent some time in California observing the northern sky, and my notes indicate that on the two occasions I observed Eta Persei I saw the various nearby fainter stars you sketched as well as the main pair - including separating the C-D pair. That was with a C8, so I guess I matched a 6-inch refractor with only 2 more inches aperture. :)

My notes remind me that I thought it a fine object; these days I can only wish it was a bit further south on the sky, or myself not so far south.

You and Norme are giving us some very nice drawings of doubles. Well done.

#13 7331Peg

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Posted 25 November 2012 - 12:38 AM

Thanks, Fred -- very much appreciated!


John :refractor:

#14 Asbytec

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Posted 25 November 2012 - 02:12 AM

Thank you, Fred. It's been enjoyable.






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