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New Horizons Parallax Program
dtolman
post Feb 3 2020, 06:48 PM
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New Horizons is going to be launching a Parallax Program this year - with planned simultaneous observations from Earth and New Horizons of Proxima Centauri and Wolf 359 on April 22nd and April 23rd.

At New Horizons distance the change in position for those two will be very noticeable - over an arcsecond - and the combined 3-d image should have some noticeable "pop" for those two stars versus other background ones.

As always this decade, the latest photo ever taken by New Horizons will be the Farthest Ever Taken.
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Mark Gurwell
post Feb 3 2020, 07:00 PM
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QUOTE (dtolman @ Feb 3 2020, 06:48 PM) *
New Horizons is going to be launching a Parallax Program this year - with planned simultaneous observations from Earth and New Horizons of Proxima Centauri and Wolf 359 on April 22nd and April 23rd.

At New Horizons distance the change in position for those two will be very noticeable - over an arcsecond - and the combined 3-d image should have some noticeable "pop" for those two stars versus other background ones.

As always this decade, the latest photo ever taken by New Horizons will be the Farthest Ever Taken.


I think the parallax is much higher than that...New Horizons is at ~47 AU, and the projected distance perpendicular to Proxima Centauri is around 41-42 AU. Thus the apparent parallax must be > 30" which would be spectacular that's true.
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Tod R. Lauer
post Feb 5 2020, 04:48 PM
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QUOTE (Mark Gurwell @ Feb 3 2020, 12:00 PM) *
I think the parallax is much higher than that...New Horizons is at ~47 AU, and the projected distance perpendicular to Proxima Centauri is around 41-42 AU. Thus the apparent parallax must be > 30" which would be spectacular that's true.


Proxima Cen will have a parallax of 32'', Wolf 359 16".
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fredk
post Feb 29 2020, 05:52 PM
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This is a very cool demonstration project. If anyone's curious how the increased parallax precision due to the long baseline compares with state of the art measurements, here's a rough estimate. One LORRI pixel corresponds to about 1" (1 second of arc). The Proxima Centauri effective baseline of 40+AU is around 20 times the usual 2 AU baseline for Earth-based parallax measurements. So a 1" LORRI precision would correspond to roughly 50 millisec precision from Earth. (Of course the star's position could be determined to better than a pixel, although how much better will depend on the S/N.)

Gaia is supposed to measure parallaxes of stars down to 15th magnitude with something like 20 microsec precision. So LORRI won't come close to telling us anything new about the distances to these stars. But of course, as I mentioned, that isn't the point - this is meant as a demonstration and as a way of getting amateurs involved. I can't wait to see the anaglyphs!
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john_s
post Mar 2 2020, 03:25 PM
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FWIW, during the navigation campaign on the approach to Arrokoth in late 2018, we were achieving an astrometric precision of about 0.1 arcseconds, even though (like the upcoming parallax demo) we were using LORRI in 4x4 binned mode, with effectively 4 arcsecond pixels. So we could do better than your estimate, though Gaia still won't have to worry about the competition.

John
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