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Unmanned > Beyond.... > Telescopic Observations
Have you guys heard about this one ?

Gaia observatory

"The satellite will determine the position, colour and true motion of one thousand million stars and over 100,000 objects in our Solar System. Gaia will also identify as many as 10,000 planets around other stars. "
"Gaia will measure distance (from parallax) out to ~100,000 parsecs; for stars ~10,000 pc away, with a Vmag of ~<15, Gaia will measure their distances accurate to ~10-20%."

You can also read about it here

or check the European space site
What's the difference here with what HIPPARCOS did in the 1990s ?
Far, far more targets, more color information for classification, much higher precision, radial velocity spectra of probably more targets than Hipparcos got in it's entire catalog.
Indeed. By the end of its mission, GAIA will have mapped the 3D positions of the stars occupying a substantial portion of the entire galaxy. The benefits are many -- one that jumps to mind is that the distances to numerous Cepheids will be known to much higher accuracy than is currently the case, resulting in a much more well-established extragalactic distance scale.

Testing the Gaia tracking concept
What has all this to do with NASA's WMAP? Well, the ground-based optical tracking concept must of course be tested. Like WMAP, Gaia will be located at the second Earth-Sun Lagrange point L2, about 1.5 million kilometres from Earth. Like Gaia, WMAP has a deployable sunshield, partly covered with insulation material and partly with solar panels. The Gaia shield is about 11 metres in diameter and inclined by 45° to the Sun direction, that of WMAP is about 4.5 metres and inclined by 22.5°. With all these parameters, WMAP is a reasonable (photo-)model for the brightness and observability of Gaia. If the sunshield materials were strictly the same, and the proportion of insulation and solar panel areas similar, WMAP could be expected to be roughly 1.5-2 magnitudes fainter than Gaia. The actual brightness difference is still uncertain to some degree, however.
Cornell Uni Library

The promise of Gaia and how it will influence stellar ages

Carla Cacciari

Abstract. The Gaia space project, planned for launch in 2011, is one of the ESA cornerstone missions, and will provide astrometric, photometric and spectroscopic data of very high quality for about one billion stars brighter than V=20. This will allow to reach an unprecedented level of information and knowledge on several of the most fundamental astrophysical issues, such as mapping of the Milky Way, stellar physics (classification and parameterization), Galactic kinematics and dynamics, study of the resolved stellar populations in the Local Group, distance scale and age of the Universe, dark matter distribution (potential tracers), reference frame (quasars, astrometry), planet detection, fundamental physics, Solar physics, Solar system science. I will present a description of the instrument and its main characteristics, and discuss a few specific science cases where Gaia data promise to contribute fundamental improvement within the scope of this Symposium.
Gaia video processing unit test model delivered
That's the first step...
On ESA's Gaia space operations page the launch date is still set for December 2011 although other websites mention spring 2012.
Scientific Community Makes GREAT Progress Towards Gaia
Holder of the Two Leashes
According to Spaceflight Now, Gaia is now scheduled for launch on September 29th with a Soyuz rocket at the French Guiana launch site.

Holder of the Two Leashes
Now this is unusual. Back on May 24th Spaceflight Now revised their launch schedule and moved Soyuz/Gaia forward ten days. According to them, launch of Gaia will now occur on September 19th.

Worldwide launch schedule

Edit 6/24: BUMMER! The launch schedule got updated again just three days after this posting, and Gaia was pushed waaaayyy back. Late in the year, no definite date.

Update 6/28: Spacecraft is complete, tested, and ready to ship out.

Testing Completed

Ready to depart

Update 8/8:
According to the latest GAIA -DPAC newsletter, they are going to ship most of the spacecraft out in early September, with the sunshield sent to South America a few days later. They are aiming to launch during the time period Nov 17th to Dec 5th.

Update 8/24

Most of the spacecraft has now arrived in French Guiana, and Spaceflight Now has a pretty good article about that, launch preparations and the mission as a whole.


And now Gaia has its own blog site:

Semi official Gaia blog site
I saw on the ESA Gaia web page that they are replacing some part based on a problem on an already launched mission, and the new target launch date is Dec 20, 2013. Anyone know what the other craft was, and what the part is?
Tom Womack
QUOTE (antoniseb @ Nov 12 2013, 03:36 PM) *
I saw on the ESA Gaia web page that they are replacing some part based on a problem on an already launched mission, and the new target launch date is Dec 20, 2013. Anyone know what the other craft was, and what the part is?

The part is a clock generator for an X-band transponder; equivalent parts apparently went wrong in some O3b Networks communications satellites launched in June.
Holder of the Two Leashes
Gaia and its Soyuz rocket are on the launch pad, with the attempt to launch it set for this Thursday. It will be in the very early morning hours for most of us in North America. For those who want to get up (or stay up?) to watch, Spaceflight Now will carry live streaming video. Their mission status center for Gaia is at this LINK.. This will be the link for the liftoff as well.

Several websites for Gaia have recently been added or changed. Here is the recent list:

ESA basic overview
ESA factsheet
ESA in depth
Scientific community advanced website (new web address)

Launch kit (in English)
Launch in 90 minutes...
Looks like launch was successful smile.gif
Lots of rather odd (to me) claims being made about the resolution of Gaia's imaging system - Human hair at a thousand miles, penny on the moon etc. I've started to dig into the science instrument documents and the expected resolution of the astrometry is in the single digit micro-arcsecond range but I'm a bit at a loss as to how a ~1.45x0.9m telescope can get those results given diffraction limits.

So I assume there's some other techniques being brought to bear that allow it to get to a "resolution" 1000x Hubble at it's best and I'm assuming that the resolution only applies in the specific case of the task in hand.

Just asking in case anyone has any pointers to the maths\theory behind what they are doing. Will be looking myself and post as soon as I find something.
Without reading the documents, just as a hint how to look at the claims:
They won't be talking of resolution in the usual optical sense, meaning distinguishing two objects, but of the determination of the position of a star.
If you take a Gauss bell curve, you can determine the maximum/average with a much higher precision than separating two superposed bell curves, where you need about one sigma.
The other trick is using two telescopes to increase the effective aperture along one line; they originally intended to use interferometry, but seem to have found an even better solution.

Edit: You'll find much more detail in the DPAC Newsletters.

To add some more basis (Newsletter 17):
Since Friedrich Bessel announced in 1844 that Sirius and Procyon had an unseen companion, it is well known that they can be detected through the wobble in the star proper motion. In fact, when the luminosities of the components are not very different, we do not observe the motion of the brightest star around the barycentre, but the motion of the photocentre, which is the luminosity centroid.

AGIS on the Powerpoint level.
Some math.
AGIS in a nutshell.
Details behind the paywall.
Ron Hobbs

Video of the launch of Gaia is awesome. It is informative, historical and just downright beautiful. It is the 1,813 launch of the an R-7 derived vehicle, the 6th from the Western Hemisphere. You can see the separation of the boosters, what the Russians call "Gagarin's Cross." As Gaia flies into the dawn, you can see the boosters fall away, looking like "twinkling stars."

Watch it full-screen and enjoy.
QUOTE (Ron Hobbs @ Dec 19 2013, 04:11 PM) *
You can see the separation of the boosters, what the Russians call "Gagarin's Cross."

Wrong. They call it "Korolev cross".
QUOTE (helvick @ Dec 19 2013, 05:50 AM) *
So I assume there's some other techniques being brought to bear that allow it to get to a "resolution" 1000x Hubble at it's best and I'm assuming that the resolution only applies in the specific case of the task in hand.

Gaia measures parallax. So the 'aperture' is up to the diameter of the Earth's orbit (EDIT: this is what allows accurate distance measurements. But as Gerald pointed out above, it is the use of two telescopes fixed at a well-known angle, repeatedly viewing a large swath of space -- plus some fancy math -- that allows angular precision well beyond telescopic diffraction limits).

Regarding the specifics of how they combine multiple measurements, in addition to the above links, this document is a good one: (start with pg 2, "Gaia astrometry in one viewgraph")
Ron Hobbs
QUOTE (pospa @ Dec 19 2013, 09:01 AM) *
Wrong. They call it "Korolev cross".

You are so right. I knew I should have looked that up before I posted. Now we can see it over the Atlantic.
ESA Gaia on Twitter
Holder of the Two Leashes
According to the latest Tweets, Gaia has successfully completed its L2 injection burn and arrived at its destination.

In addition, the camera has been turned on and has sent its first images. Currently undergoing quite a bit of testing, but so far it looks good too.

Article on the camera testing at this LINK.

Update: Gaia enters its operational orbit.

Well, now it's going to be a few years ...
Doug M.
GAIA is going through shakedown -- testing and calibration. (That's supposed to last until May, I gather.) So they just posted a first test image: Apparently there won't be a lot of these, since making images isn't what GAIA is about.

Doug M.
Tom Womack

is the equivalent image from Hubble; I'm guessing they're using NGC1818 as a calibration target because it has the very distinct red and blue star series that you can see in the Hubble shot
Good overview of current understanding of Gaia's stray light problem and its effects on observations.
Gaia enters routine phase:

"Last week Friday, 25 July 2014, Gaia started its routine phase by scanning the sky for 28 days using the so-called ecliptic-poles scanning law. This is useful to bootstrap the basic calibrations of the data. After these 28 days, the nominal scanning law will be used to determine how Gaia is scanning the sky. Although the commissioning phase has ended, some activities remain to be completed. The root causes of the stray light and the basic-angle variations have not been found yet."

More at
New posted paper is claiming that Gaia will be able to detect 20,000 jupiter mass planets (15-27k technically) over its 5 year mission, and some 70,000 (!) over a 10 year extended mission. For reference, there are around 2000 known exoplanets as of today - and most of those are from the Kepler mission... amazing to think it'll increase by an order of magnitude over a decade. Gaia currently records information on 40 million stars a day - according to a recent tweet approaching 10 billion observed over the mission.
Gaia's Data Release 1, based on observations between 25 July 2014 and 16 September 2015, is due out Wednesday. It includes preliminary positions for over 1 billion stars and preliminary positions, parallax, and proper motions for over 2 million stars. Contents summarized at ESA's Gaia DR1.
Wow, Look at the LMC in the hi res png file at

No doubt about its spiral structure there!

QUOTE (antipode @ Sep 15 2016, 06:50 AM) *
No doubt about its spiral structure there!
And the LMC also shows rotation. Arrticle available through ArXiv..
Holder of the Two Leashes
One of the more entertaining ESA products to come out of the Gaia release is this newly posted YouTube video showing how the Orion constellation will evolve over time:

Orion from now till 450000 AD

No corrections made for Betelgeuse possibly blowing up (whose timing is unknown in any event). Also notice the Hyades star cluster moving in.

Another earlier YouTube from ESA showed an approximation for the whole sky for five million years.

Future of Two Million Stars

Recommend going full screen on both of these.
Holder of the Two Leashes
Heads up. The astrometry revolution is about to start.

Gaia's second data release is coming up on April 25th. It will have 22 months worth of observations crunched into it. None of it will be relying on Hipparcos data anymore, it will be purely self contained.

Here is a description:

Gaia DR2

In other news the spacecraft had a hiccup back in February when it went into safe mode for ten days. It was a transponder problem, and there is some concern it could reoccur.

Enough data has already been gathered to date in order to have a Data Release 3 in late 2020. That should be the last release before the final catalog. That is, unless they extend the mission.

Update 21 April 2018

The press kit for the upcoming data release is now available HERE as a download.
Here is a clip set to 'Chimaerica' by Jóhann Jóhannsson cropped to 3 minutes due to Flickr video limits...

Made with 800 Megapixel equirectangular version mapped to sphere.

Full 3m24s 4k60 version over on Youtube
I have created this image of the Milky Way from the raw CSV data. It's similar to ESA's but has more contrast and is more 'blown out' at the center of the galaxy.

32Kx16K version
Holder of the Two Leashes
Some early results from the new data release are being published:

Milky Way history and other stuff

“dynamically driven double-degenerate double-detonation” (D6)
You have to love that one.

Epsilon Aurigae mystery solved
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