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RickJ
2015-Oct-18, 02:46 AM
Or not.

Back on November 28, 1967 a grad student, Jocelyn Bell, discovered something very odd in the data of a radio object. No one could explain the emissions that pulsed with a regularity of an atomic clock and thus far beyond anything ever seen in the skies. No one could understand what it was and some fell back to the old, even then, pseudoscience argument from ignorance, since it isn't anything we can explain it may be due to aliens idea and some even started calling it LGM for Little Green Men. It turned out it was the first known pulsar of which we know know of thousands. In a case of "Déjà vu all over again" we now have a star seen in the Kepler data hunting for planets, KIC 8462852 to use the Kepler Input Catalog number (it's Yale number is TYC 3162-665-1), with brightness variations that no one can explain. So far there are major problems with all astronomical explanations. So again falling back to the pulsar era the alien possibility is again being toted out. Yes the pulsar could have been an alien signal but wasn't. This too could be due to alien activity but I suspect it will again herald the discovery of something new in astronomical knowledge maybe opening up a whole new field of study as the pulsar has (will it get a watch named for it?).

Last night was the first night I had a hope of imaging it since it was announced. All I had were sucker holes but after 4 hours of trying I finally got enough data to put a quick image together. I found no spectroscopic classification for it but with a B-V value that ranged around .5 to 1 (sources varied greatly) I expected a slightly red star but instead got a slightly blue one. I found no color image of the field but for one put together from the POSS data's red and blue plates by Aladin. That too showed it slightly blue. Now I'm confused. I doubt this has anything to do with the odd deep dips in the light curve of this star as these various measurements were random and highly unlikely to hit one of the dips in the curve. But I found nothing on how its color did change during a dip. So for now this is yet another mystery. I suppose somehow the clouds going by altered my color data but after calibration using NOMAD data the other stars all appear correct, this one is the exception. Also I grabbed three short exposures (10 seconds) during an apparently clear sucker hole and it showed the same slightly blue color. So I'm quite confident the color is correct, at least for last night. I took many color frames, all but one of each color hit by clouds, so only used the cloudless color frames. If it stays clear tonight I'll try again for better color.

For more on this star including the strange light curves that started all this, see Phil Plait's article (http://www.slate.com/blogs/bad_astronomy/2015/10/14/weird_star_strange_dips_in_brightness_are_a_bit_ba ffling.html) on it. Another good article on it is in the Washington Post (http://www.washingtonpost.com/news/morning-mix/wp/2015/10/15/the-strange-star-that-has-serious-scientists-talking-about-an-alien-megastructure/?wpmm=1&wpisrc=nl_p1wemost).

At 12th magnitude a large Dob might show color. If so I'd like to know what color you see it as. I saw no color in my 14" but then my eyes aren't what they used to be either. I used far less stretch than normal to suppress the great number of faint stars that made the field a mass of stars. It's position is 20h 06m 15.45" +44d 27' 24.8".

The field is full of stars, many of which Kepler has studied. The star is the slightly blue one in the center of the image. I've marked it in the cropped image.

EDIT: Since this was posted several have said the B-V I was finding is likely wrong as it is an F3 IV/V star. That is it slightly blue exactly like I picked up. The classification may indicate it is moving from main sequence to sub giant stage. Not good for life if it exists in the system. But some stars are naturally this way which could mean one or two billion years of stability. We needed far more but that is a sample of one so may be meaningless.

14" LX200R @ f/10, L=4x10' RGB=1x10', STL-11000XM, Paramount ME

Rick

Jeff Root
2015-Oct-18, 12:56 PM
By "stretch", I take it you mean you increased the contrast
so that bright areas are brighter and dark areas are darker.
Can you explain why you do that in general and how in this
case not doing it too much supresses the great number of
stars that made the field a mass of stars? I increased the
contrast on the Hubble mosaic of M101 that is my desktop
wallpaper (conflicting metaphors!) in order to make the
individual stars more prominent so that they look more
numerous, even though it loses a lot of the overall haze
that is of course caused by vast numbers of dimmer stars
which are too dim to distinguish as individuals.

-- Jeff, in Minneapolis

TJMac
2015-Oct-18, 01:32 PM
I wonder how many people immediately thought of the pulsar incident. (if you want to call it that)

That was indeed my first thought. "Hmm, didn't they suspect aliens back in the 60's, when they discovered the pulsar?" Which is about the limit of my knowledge on that subject, to be honest.

Hope springs eternal. Perhaps if it can be determined that it is an artificial construct, a few dollars will break loose toward our space program.

TJ

Spacedude
2015-Oct-18, 01:48 PM
Quasars were another mysterious head scratcher, for at least 2 decades to resolve those if memory serves? But with pulsars and quasars we had several to observe unlike this one weird star system that has yet to become one of several. Time will tell.....

RickJ
2015-Oct-18, 08:19 PM
By "stretch", I take it you mean you increased the contrast
so that bright areas are brighter and dark areas are darker.
Can you explain why you do that in general and how in this
case not doing it too much supresses the great number of
stars that made the field a mass of stars? I increased the
contrast on the Hubble mosaic of M101 that is my desktop
wallpaper (conflicting metaphors!) in order to make the
individual stars more prominent so that they look more
numerous, even though it loses a lot of the overall haze
that is of course caused by vast numbers of dimmer stars
which are too dim to distinguish as individuals.

-- Jeff, in Minneapolis

Stretch means something quite different. A CCD image contains values ranging from 0 to 65535 of intensity but a monitor can reproduce only a range of 0 to 255. Somehow the image has to be shoehorned into those few levels. So the stretch is a very non linear process. Most of the image is contained in the very lowest levels which are pulled up while the brightest regions can't be without losing detail there. That's what happened to your image. HST folk intentionally held back the stars in their stretching of the image so as to allow the nebula detail come through since it was the subject of the image. It is, with proper tools, possible to stretch the nebula and stars separately so you can bring up the stars without blowing out the nebula as you did if that's what you want. HST did the opposite as they wanted the nebula to not be overshadowed by the stars. Each imager has to make such decisions when stretching an image. What does the imager want from the image and stretch the various components accordingly.

In this case I held back the huge mass faint stars and set my black point to wipe them out entirely. Even then the star in question doesn't stand out as strongly as it would visually. I was working fast to get this out for some schools that had asked for it. When time permits I'll redo it (from original data not the currently stretched image as with 255/256ths of it lost that wouldn't work very well. Same as yours didn't starting with all that data missing. Thus in one sense I greatly reduced contrast while in another I increased it greatly. But since this is very different from using a contrast slider imagers call it stretch.

I should add that while the CCD returns 65536 levels of intensity not all of those are "real". A CCD generates noise when converting from analog to digital. The wells of many CCDs hold fewer than the equivalent of 65535 electrons. Some only about 20,000 yet the CCDs gain will spread these over the 65,000 levels. Add that such a CCD may have read noise of say 5 electrons (if low noise). This means the real value is within 5 electrons of the value measured. So you have 20,000 levels but an error of 5 leaves 20,000/5=4000 meaningful levels. This too has to be considered when stretching an image. One way is by stacking many images. Stack 4 images and the real data is increased by 4 but due to how noise adds the error of 5 has been reduced to the square root of 5 thus giving me about 8000 levels to work with. Stack 16 and it is now 16,000 etc. This helps to bring out faint low level features otherwise lost in the noise level if stretched to bring it out.

Another consideration is that it often helps to stretch color data very differently from the luminance data. I stretch color data to preserve color accuracy and pretty much ignore everything else since the detail is provided by the luminance frames which are taken separately.

Stretching data is more an art than a science and I'm still learning the process.

Rick

DaveC426913
2015-Oct-19, 05:20 PM
Most misrepresentative. Thread title. Ever.

RickJ
2015-Oct-19, 05:46 PM
Gee I thought it appropriate as an astro version of the old "Here be Dragons" idea. It wasn't true for dragons or even that old maps said that and I doubt it true here for aliens. Both were arguments from ignorance. We don't know so its dragons or now aliens.

Rick

Jeff Root
2015-Oct-20, 08:47 AM
When I saw the thread title, in the context of the sub-forum
and the original poster, I correctly guessed the subject.
But I didn't forsee the nifty Rachel-Maddow-style intro!

-- Jeff, in Minneapolis