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The Deepest Photo Ever Taken
Astroturtle writes "Astronomers using the Hubble Space Telescope's powerful new Advanced Camera for Surveys (ACS) have taken the deepest visible-light image ever made of the sky. The 3.5-day (84-hour) exposure captures stars as faint as 31st magnitude, according to Tom M. Brown (Space Telescope Science Institute), who headed the eight-person team that took the picture."
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May 7, 2003 | Astronomers using the Hubble Space Telescope's powerful new Advanced Camera for Surveys (ACS) have taken the deepest visible-light image ever made of the sky.
The 3.5-day (84-hour) exposure captures stars as faint as 31st magnitude, according to Tom M. Brown (Space Telescope Science Institute), who headed the eight-person team that took the picture. This is a little more than 1 magnitude (2.5 times) fainter than the epochal Hubble Deep Fields, which were made with the Hubble's Wide Field and Planetary Camera 2. It is 6 billion times fainter than what can be seen with the naked eye.
Brown and his colleagues chose to point at a spot 1 southeast of M31, the Great Andromeda Galaxy, in order to get a census of faint stars populating M31's outer halo. The full ACS image is about 3.1 arcminutes square, the size of a sand grain held at arm's length against the sky. The ACS magnifies this small field into a vast panorama of some 300,000 stars and thousands of faint background galaxies. At M31's distance of 2.5 million light-years, the faintest of the stars are slightly less luminous than our Sun. A large fraction of the most distant galaxies appear patchy and irregular, testimony to the collisions and mergers in the early universe that built up the familiar galaxies we see closer around us today.
Most of the stars in the image indeed proved to be in M31's halo, judging from their colors and brightnesses. Moreover, they show a surprisingly wide range of estimated ages -- from 6 to 13 billion years, compared to 11 to 13 billion years for our Milky Way's halo stars. Perhaps M31 has captured and torn apart younger dwarf galaxies than our Milky Way has done. Or perhaps M31 underwent a massive, disruptive merger with a single large galaxy billions of years ago; in this scenario some of M31's younger disk stars could have been flung into its halo. Or maybe some combination of these events triggered waves of star formation in regions that ended up in M31's outer fringes.
The image was made in two colors: near-infrared and "visual" (a band spanning the part of the spectrum running from yellow through green). The renditions displayed here were crafted to resemble true-color views by interpolating from these two colors. These vignettes each show only about 1 percent of the ACS image. The full image is available from the Hubble Telescope's press site at various qualities and sizes (up to 128 megabytes), along with more highlights and a finder chart showing its relation to M31.
Plans are afoot for an even deeper "Ultra-Deep Field," which will use ACS for longer exposures in four colors and go slightly fainter still.
Bush is on fire and its not good for my lungs.
Imagine a Beowulf... um. Seriously, how do you cope with reciprocity failure in a 3.5 day exposure. I would have thought that stray heat or electron flow would turn the whole image to static with such a long exposure. HST must consist of unfathomably cool (literally and figuratively) electronics.
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Just how many photons they detected for the faintest star.
"Eve of Destruction", it's not just for old hippies anymore...
3.4 day exposure? Even for a space-based platform, that has to be really stable to produce a good image. Does anyone out there have any info on how they maneuver the telescope to keep it pointing at the same point while minimizing shifts in the field?
Derek
Don't Panic...
It is still pretty incredible...pointing an object the size of a bus and accurately focusing it on something the size of a spec of sand...really, really, really far away. All while moving at a relative 26,000 miles an hour or whatever to keep it up in the sky...Not to mention the orbial speed of the earth itself... Only took 8 guys, several computers, and millions of dollars worth of equipment. Oh yeah, and that one maintenance run made a few years back to keep it pointing straight.
Who is this that even the wind and the waves obey Him? Surely this computer must submit also!
And, to think I used to complain about having to get the tripod out for exposures that were longer than 1/8th of a second! I'll never comlpain about slow film or lenses again!
Yeah, and you'd think NASA could afford 1600 ASA film for the price they paid for hubble...
I mean geez!
Direct link to the full-resolution JPEG. (~4.9MB)
/ a/formats/full_jpg.jpg
http://imgsrc.hubblesite.org/hu/db/2003/15/images
See also the press release with tons of photos. Enjoy your new wallpaper ! :)
Here is a link to a higher resolution image.
Hubblesite.org
The image is not actually a single exposure of 3.5 days in duration, but is actually made from 250 separate exposures taken from Dec. 2 to Jan. 11, 2003. The total exposure time was 3.5 days.
For those who are interested, the original hubble press release is located here.
The site includes the image in a variety of different formats, including a 123 MB tiff file.
Aristotle writes: "Philosophers using the Bubble Head Telescope's powerful new Advanced Cognition for Sophistry (ACS) have taken the deepest thought ever thunk. The 3.5-day (84-hour) idea captures notions as powerful as 31 SBU (Silent Bob Units), according to Plato (The Platonic Academy), who headed the eight-person team that contemplated the thought."
For the love of all things scientific, have mercy on their 122MB TIFF image.
And to think that we've turned servers into slag by Slashdotting a 43kb page.
It all goes downhill from first post
If you look at the image, there are some odd streaks that go from red to blue (or blue to red).
I'm just curious here, what are they? I thought maybe it could be a bit of space debris that whizzed in front of the camera, but with an exposure of 3.4 days, the streak would go from one side or another.
What moves that far in 3.4 days? A comet? A meteor? A star?
And that big bright cluster in the lower bottom, what's that? It looks pretty close galaxy-wise.
It's a neat pic for sure, a little blurry, which makes it less jawdropping than other hubble efforts but makes sense for a 3.4 day exposure.
Note - I didn't make any goatse or Uranus crack this whole post. You're welcome.
I don't need no instructions to know how to rock!!!!
As they spin, the momentum from their motion causes the telescope to move.
Well, it's techincally a litter different than that. The wheels don't actually cause hubble to translate within a plane. Instead they rotate hubble. By turning the spinning wheels, a torque is exerted on hubble, causing it to rotate.
neurostarSomething I've wondered for a while... what's up with the points coming off the stars? I've always accepted it when I see it with my own eyes because I don't expect my own eyes to be optically perfect, so I always thought it was distortion, but looking at the full image I see that the brightest stars once again have points coming off of them in four directions. Typically they are directly up, down, left, and right, but in that image, they appear to be about five to ten degrees off that.
The biggest example I see is about 3/4s of the way to the right and about 1/5 of the way down on the image, where there is a huge-looking star.
Why four points? Why do we see them even when the star itself is not in the picture (look on the top border for examples, like the one almost directly in the middle)? I guess I would expect that if the light source is too bright the spread would be in a circular formation and simply blur the star, not blur it in just those four directions so much stronger then the rest.
Is it just QM at play? If so, why it is almost always directly up, down, left, and right, instead of random and perhaps even changing over time directions (which probably would get right back to simply looking blurred)? Detector flaws?
I know there are countless galaxies out there...but they are so far away, I was extremely surprised at how many galaxies I could see in the big 4MB JPEG.
I'm out of my mind right now, but feel free to leave a message.....
http://sja.ucdavis.edu/images/einstein-lg.jpg
Know what I like about atheists? I've yet to meet one that believes God is on their side.
desktop background ever created :) Its sure worth the effort, however!
Modern optical/IR/UV telescopes typically have a large primary mirror, which reflects light back to a smaller secondary, which reflects the light through a small hole in the primary to the detectors. The secondary is supported by little rods. It is diffraction of light by those supports which cause stars to have distorted shapes.
(Astronomers understand the diffraction issues very well... it's usually not a problem; it just looks weird.)
- A friendly neighborhood astrophysicist
I just thought about how detailed the full size pic is, and how to appreciate that without a poster printer. I'd like to see something similar to osx's default screensavers (with the softly zooming pictures of trees/beach, etc) and have it use this picture.
I'd like to see it zoom in to the picture, while also changing x/y of the camera on a spline (etc). And each time choose a different starting point, and make it's speed adjustable.
All of those high-res pics are beautiful! maybe i'm 'a gonna dust off the 'gl..
The grandeur of such an image almost forces one to reasses their place in the world. To think that the area in the photograph is equivalent to the area covered by a grain of sand at arms length is mindnumbing. The universe is unbelieveably amazing.
Will be about 20 billion light years, since we think the universe is about 20 billion years old.
e ID =000F1EDD-B48A-1E90-8EA5809EC5880000
For an interesting article, see:
http://www.sciam.com/article.cfm?colID=1&articl
On parallel universes. Very interesting reading. If you're at a university, you will be able to browse the site's archives and access the nice PDF version of the article (which has the pictures supersized to full-page size).
social sciences can never use experience to verify their statemen
I'd hate to have to hold my finger on the button for that long without shaking the camera.
*This is a lame joke*
it is only after a long journey that you know the strength of the horse.
http://wuarchive.wustl.edu/users/tom/mirrors/hu
is a mirror of the full JPEG - about 5M. Enjoy.
Something I've wondered for a while... what's up with the points coming off the stars?
As was mentioned in another post, those are diffraction spikes from the supports for the secondary mirror.
Newtonian reflectors and classical Cassegrain telescopes support their secondary mirror with "spiders" that produce diffraction spikes. There have been various efforts over the years to eliminate these from that type of telescope. One method is to seal the tube with an optical flat (a flat piece of optical glass) which supports the mirror. The trade-offs include longer times for the scopes to reach temperature equilibrium, distortion from imperfections in the optical figure of the flat, and slight light loss. Other attempts have included the use of spiders with curved support arms, which reduce or eliminates spikes at the cost of slightly degraded overall image contrast.
Other telescope types, such as refractors, Maksutovs, Schmidt-Cassegrains, and Yolo reflectors have no diffraction spikes, but they are all more optically complex (Yolos, for instance, require toroidal mirrors) and are more difficult to produce as a result. Refractors have the added problem of chromatic abberation, which is the fringing of color on the edge of bright objects. Various complex, multi-element objectives have been developed to reduce, or even practically eliminate, this problem. The problems are optical complexity, cost, and light loss. Figuring a 3-element objective lens for a refractor means grinding six optical surfaces with precise curves. Compare that to a Newtonian which has a single parabolic primary mirror and a flat optical secondary.
There are many other telescope types than the few popular types I mentioned here and each have their proponents. Most designs that have survived the test of time can be made to perform well, but each has trade-offs.
Does anyone know if there is a BitTorrent file out for the 128mb TIFF? the nasa servers are a bit slow and I feel my hardware cycles and bandwidth could be of use...
Unretouched excerpt from full-resolution image.
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Moderators: Please don't encourage this guy in any way, even if this comment of his may very well contribute to the technical discussion.
He doesn't deserve positive karma until he learns some respect. When he learns to treat people of all colors as he wishes to be treated himself, then perhaps he can contribute to the discussion in a worthwhile manner.
What goes around, comes around. Paranoid delusions about people of other races (sexes / political and religious beliefs) are so 1700's and have no place in an advanced civilisation.
The most intersting thing about these images now is the fact that they are not blurred:
This Nature article describes how....hmmm I had better quote:
"As a beam of starlight hops towards us through countless Planck times, its speed varies. This would smear the beam out so that different parts arrive at different times and distort our picture of where it came from. The longer the journey, the bigger the smear."
So that means that these deep Hubble photographs should all get more blurry the deeper you look and not razor sharp like we have come to love.
Its a fascinating problem!
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I've read that paper, and there's a major problem - they do the calculation in the direction of propogation, but then try to use the result in the transverse direction. You can't do that. No one's done the calculation in the transverse direction, so we still don't know what the theoretical prediction should be.
[TMB]
a = angle subtended by capture (radians) = 2*pi*3.1/(360*60) = .000901
.0000008118
.0000000646
b = area of capture on a sphere of radius 1 =approx= a^2 =
c = fraction of entire sphere = b/(4*pi) =
d = number of visible stars in entire sky = 300000/c = 4,643,000,000,000
So that means almost 5 trillion stars are visible by Hubble in the entire sky. That's a lot of stars to catalog. (Assuming I didn't err like they did in the $97 trillion RIAA calculation... someone pls double check and flame me if appropriate.)
Ok, here's the calculation for you curious types, regarding how many photons arrived from the faintest star in the picture:
Let's suppose that the picture was taken in the "V" filter. I just happen to have the number of photons per second per meter squared that arrive from a star of 20th magnitude: 86.157. (taken from here ).
So the faintest stars in this picture are 31st magnitude? That's 11 mags fainter than 20, which by the handy old formula
mag1-mag2 = -2.5 * log(flux1/flux2)
which means that the 30th magnitude star puts out about 4x10^(-5) times as much flux.
Using the reference star's flux from above, this means that 0.0034299 photons per second per meter squared arrived at Hubble. The exposure was 84 hours, and the area of Hubble is (2.5m)^2*pi, so tada:
The total number of photons in the picture from the faintest star is: 20365.83
Still not too shabby. They probably could have found even fainter stuff.
Don't forget, this is only 3.1 arcminutes^2 of the sky. that's the size of a grain of sand held at arms-length against the sky, according to the article. That leaves a ton of sky still unseen.
You like your new Mac more than you like me, don't you, Dave? Dave? I asked...She said Yes.