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61 cygni

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#1 Tyranthrax

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Posted 31 July 2013 - 12:26 AM

not enough pictures in this column. . This look right to you guys? From what I read it is supposed to be orangish, but mine came out more yellow. .

Is 61 cygni the one on the bottom? it looked little larger and brighter I wasn't sure or maybe it was cause it was closer?

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#2 Cotts

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Posted 31 July 2013 - 08:29 AM

The pair carries the name 61 Cygni. The individual stars are 61 Cygni A (the brighter) and 61 Cygni B (the fainter).

Excellent photo, by the way. Would you share your technical info, please? Scope, focal length, etc....

Dave

#3 Tyranthrax

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Posted 31 July 2013 - 09:52 AM

Thanks for the help, I wasn't sure if it was truely the brighter one or if it was an illusion, much like if you hold a fish out in front of you it looks bigger.

Ijust use a Celestron 6se I bought in febuary, the2x barlow that came in the case and the camera is an Orion StarShoot Deep Space Video Camera II this maba jamba right here http://www.telescope...s/Orion-Star...

I use the default settings generally, I'ld have look at the fine details, but once you get the hang of the electronic shutter, the gain, and other settings, they comeout pretty decent. I spent alot of nights scratching my head and trying different things. to get it right, sometimes I'm a winner and sometimes all I hear is that sound it makes on the price is right when the contestant looses.

For processing I put it in registax6, (no more than 75 secs of recording) and I get a pretty decent result. its a matter of going each frame and finding the top frames. Pick teh best of the best as the set point use the worst of the best as my limit and the first pass is pretty decent. The biggest thing that has helped is the RGB alignment. I use Photo shop to clean up the back ground. (I get a bit of video noise and I darken it up, grabbing teh stars I just adjust the levels and curves, so it brings the dark up and the light down, aand enhances contrast. That's about it. one could adjust the color if they wanted to, but I'm slight OCD so I can't do it and not feel like its not cheeting, the true colors are what is important. You can tell if its been altered becuase the stars have a look, its bright white at points I look at directly in the photo, much as the star itself, but it seems the points right outside direct view have the color tint to it. A photoshop of the object looks too opaque and looses this effect. I am certain if you were relally good with it you could reproduce that affect. . but I am no where near that skill level, and it wouldn't feel right, like cheating.

COlor wise is this on or off? I recall seeing it yellow like this, but when I read up on it it claims orange. o.O

Another hting that helps is the skies I have are generally pretty awesome, my town has this weird thing, I'm not sure if it is the muntains or not, but a storm will occur in Reno itself, but as it comes out our way it goes around my town I see about 6 rains a year. its better after a rain too knocks what dust is in the air down. and we don't seem to like street lights in town. See?

http://cleardarksky....eRdNVkey.html?1

#4 dc_robert

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Posted 31 July 2013 - 11:10 AM

As it happens, I was observing this pair Monday night (among other binaries).

They were definitely orange in my refractor.

#5 Tyranthrax

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Posted 31 July 2013 - 11:14 AM

TY, quality is important, I'll keep checking back with this one in the sky see if I can nail the colors. I thought it would help if the doubles forum had some images to help people get interested and to know what to look for. most images I see online are not very good representations of some of the beauty.

is it more of a yellow orange or redder orange or just orange? I hope that makes sence.

#6 dc_robert

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Posted 31 July 2013 - 11:29 AM

Almost perfectly orange, if memory serves. Could have been tending toward the darker orange, but that may have merely been a function of my light polluted site.

#7 Tyranthrax

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Posted 31 July 2013 - 12:14 PM

Thanks I'll definatly give it another go this weekend as things wind down. I did a Graffias one no one seemed to mention anythign on :( came out weird was bluish one side and yellow ish the other, I think I need to try again on it. I had to find a balance between the two. this weekend would be good. I wam trying to go down the list but having a bit of a time getting them all. . .

#8 GlennLeDrew

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Posted 31 July 2013 - 03:04 PM

The best general indicator of visual star color is the B-V index, at least for 'normal' stars not having extensive spectral line blanketing or emission lines. It's surprising to not see these data among the that in the annotation; I'm certain quite accurate B-V exists for this wide, bright duo.

#9 Ed Wiley

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Posted 31 July 2013 - 03:24 PM

Nice image! I am guessing F20 with the 2x barlow. Can you share your integration times? Do you do any measuring?

Ed

#10 Tyranthrax

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Posted 31 July 2013 - 03:44 PM

Glen , I do a search on the target, then pop tha tin there my friends and family enjoy seeing thse things as I started posting them on my social page, So for them to sit and read an article I foudn it easier to pu tthe easy stuff to know in the picture. I have n idea what that b-v index is. Wha tis it? I try no tto put too much in there to take away from the picutre itself.

Ed no its a Celestron 6se, 2x barlow and an orion deep space video imager II. about 30-45 sec record with it stacked in regixtax6. Use photoshop to adjust levels to bring the noise out of the back adn add contrast to the colors. about 30 min aof work there from registax to levels.

#11 GlennLeDrew

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Posted 01 August 2013 - 12:25 AM

The B-V color index is the difference in brightness between the photometric blue and visual bandpasses. These are standard filters, the full set of which is UBVRI (UV, blue, visual, red and IR.) Broadband photometry is an important source of information. For us visual observers the color of stars determined from the B and V magnitudes is very pretty correlated to temperature.

The bluest stars have a B-V index of -0.34, meaning the blue magnitude is brighter than the visual magnitude by 0.34 magnitude.

White stars (which nonetheless appear bluish to our Sun-adapted eyes) like Vega have B-V = 0.

Going to ever yellower and redder stars, B-V is increasingly positive (visual magnitude being brighter than blue). Our yellowish G-type Sun is 0.62, K and M stars are from near 1 to 1.5 or so, and Carbon stars can be about 2 to 5 (very red!).

Where known--more often for (non-faint) primaries only when separation is small--the B-V color index is a very valuable observational datum for double star observers. Actually, for observers of stars in general!

An interesting aspect of the B-V color is that it can allow to estimate the amount of interstellar extinction due to dust in space. For example, if we observe an A-type star whose intrinsic color should be, say, 0.1, but see that the actually measured B-V = 0.8, we know the color excess is 0.7. Assuming a typical visual extinction to color excess ratio of 3.1, the total visual extinction is 0.7 * 3.1 = 2.2, meaning the star is dimmed by 2.2 magnitudes, or a factor of 7.4.

Not that this last is at all needed to know for the observer. :grin:

#12 fred1871

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Posted 01 August 2013 - 05:07 AM

A useful explanation from Glenn. I did a quick check on 61 Cygni to see what the data is - only Wikipedia, so if anyone has better data please chime in.

Spectral types are given as K5V and K7V - main sequence (MK class V) orange stars (type K). B-V colour indexes listed as +1.139 and +1.320. A nice fit for the colour most of us see in this double and for Glenn's notes on B-V figures as perceived colour.

#13 Tyranthrax

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Posted 01 August 2013 - 08:18 PM

fred can you help me out with that? I'ld ask questions but I have no idea what to ask. is it a color thing?

#14 StarDusty

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Posted 01 August 2013 - 09:14 PM

I looked back through my images of this double. Here is my last measurement-image captured with a monochrome camera and a 4" f/28.5 Schiefspiegler.

It is one of doubles included in my JDSO paper found here:

http://www.jdso.org/...lsbury_5_11.pdf

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#15 GlennLeDrew

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Posted 02 August 2013 - 03:49 PM

fred can you help me out with that? I'ld ask questions but I have no idea what to ask. is it a color thing?


One could say it's a temperature thing. Just as a piece of iron, as it's increasingly heated, goes from a dull red, to orange, yellow and white, so too do the gases at the surface of a star. And the temperature of a star's surface has a profound effect on the state of ionization of the gases making up its atmosphere, which impacts the presence and intensity of spectral obsorption lines, which in turn determines the spectral classification.

And so there is a pretty good correlation between temperature, color and spectral class. But far fewer stars have been classified than there are stars having a known color index (even if crude for the fainter ones.) In lieu of a spectral type, a B-V color allows to make a fairly good guess at the spectral class, e.g., B8, F5, etc.

But as I hinted at earlier, such a guess must consider the possibility of interstellar extinction and reddening. If the data suggests great distance, and the direction is toward the band of the milky way (where dust clouds are more concentrated), there is an increased likelihood of some amount of anomalous reddening, making the star appear redder than it really is. In the main, a probably small fraction of known binaries are so affected, for it requires distances generally more than about 1,000 light-years in most directions (varying from as near as 350 to several thousand, due to the patchiness of the clouds) for extinction to amount to anything at all notable.

In the case of doubles, and more so the closer they are, visual impressions of color can be significantly altered, due to color contrast effects. Where known, the B--V index is a much more reliable indicator of true color.

This is because stars are essentially black body emitters, and in the visual spectral regime are basically white with varying tints of blue or red. Hence the great utility of the B-V color index. A black body emitter that is visible to the eye has an emission intensity with wavelength curve that does not admit the possibility of such colors as purple, lilac, green, mauve, etc. for instance, to be green, the black body curve would have to be inordinately weaker in both the blue and red than it can be. Yet a star having the required B-V color (near zero, or bluish-white late B to early A) can *appear* greenish when in close proximity to an orange K-type star having B-V of about 1.2-1.5. The contrast of the complimentary colors, contributed to by the eye's own bias in sensitivity in the green, is what does this. But such a star in isolation is perceived as bluish-white.

And the 'purple' type colors are impossible for two reasons: the black body curve cannot have *both* the red and blue stronger than the green (and even spectral line blanketing cannot achieve this); and the eye's own response is biased toward the green portion of the spectrum, ensuring that red *and* blue cannot both be dominant. Yet visual impressions abound where such is suggested.

#16 george golitzin

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Posted 02 August 2013 - 05:03 PM

Last time I looked, I saw 61-Cygni as a nearly matched gold pair--call it a deep yellow verging on orange. A very pretty double, I thought. But I've given up trying to understand color perception, particularly my own. Objective measures such as the BV index are certainly helpful in testing one's own perception against a standard.

#17 azure1961p

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Posted 03 August 2013 - 07:26 AM

You've got pretty large scopes George. The bigger aperture tends to make the orange appear yellow and gargantuan would bleach it even more.

Pete

#18 azure1961p

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Posted 03 August 2013 - 07:29 AM

Looks over exposed a but and the orange shifted to yellow. Too some tweaking during or after the exposure might be in order.

Nice image though.

Pete

#19 ssmith

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Posted 03 August 2013 - 10:16 AM

Here is a recent photo I took using an Olympus E-PL1 camera
on my 4" refractor.

Steve
Castle Rock, CO

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#20 azure1961p

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Posted 03 August 2013 - 10:35 AM

See now there's a good case in point with aperture/exposure/settings.That and auto settings, at least on my DBK don't always do it and a little adjustment is in order.

Very very nice image.

Pete






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