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One Billion Pixels

RogerTheDodger

By RogerTheDodger
in The Astro Lounge

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661-pete

661-pete

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Glancing through the article:

Over a five-year period, the satellite's e2v array ... will make an unprecedented 3D map of our Milky Way Galaxy.
I thought at first that "3D" was just a bit of journalistic embellishment. But maybe not: the astrometric powers of this device will be staggering, and it really will map the Milky way in "3D"...

And to think that the most precise currently in-use astrometric data (the Tycho catalogues) come from the Hipparcos satellite which had an aperture of just 290 mm - 11½" - no larger than many of SGLers' telescopes... There's some clever pieces of kit up there in orbit...

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cantab

cantab

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As we start measuring parallax for more and more distant stars, what do we use for the "background"? Since surely what the early measurements used as background we're now measuring the parallax of that.

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FraserClarke

FraserClarke

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As we start measuring parallax for more and more distant stars, what do we use for the "background"? Since surely what the early measurements used as background we're now measuring the parallax of that.

A very good point :rolleyes: No star in the galaxy is suitable, and even stars in nearby galaxies move too much to be useful (and are too faint, more importantly). For a few years now, there has been new standard coordinate system ICRS/ICRF which is based on extragalactic sources such as quasars. If you're really interested in the gory details, USNO has a good overview;

ICRS Narrative

Another problem is knowing not just where you're looking, but where everything else is too... At this level of precision, you have to take into account things like the gravitational lensing effect of Jupiter, which will make the whole sky 'breath' depending on where it is... Precision astrometry is a scary job when you start looking at the details ;)

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JamesF

JamesF

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Funny you should say that, i noticed today that my gf's phone has a 600mhz cpu in it... I remember building a desktop with one of those!

I dunno. Don't know you're born these days... The first home computer I used had a 1MHz CPU, which was about par for the time. The first Intel-based computer I owned had a 12MHz CPU.

I feel a "Four Yorkshiremen" sketch coming on :rolleyes:

James

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glowjet

glowjet

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I dunno. Don't know you're born these days... The first home computer I used had a 1MHz CPU, which was about par for the time. The first Intel-based computer I owned had a 12MHz CPU.

I feel a "Four Yorkshiremen" sketch coming on :rolleyes:

James

I remember buying my son a whole 1/2 meg upgrade for his popular games computer of the period, payed thick end of a £100 for it and it was the size of a large block of cheese, how times have changed.

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