My attempt to visit all the beaches on the Big Island is going well.?ÿ
Took some time off from my hard work and went to an interesting presentation from the Keck Observatory explaining the only photo of a black hole (Powehi) which was taken in April using?ÿinterferometry and as one of the presenters explained a 9 pixel image.
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They did say one thing that made me wonder; the telescopes used to generate the image needed to be located within a very small tolerance from each other, something like a billionth of a meter. I can't think of a way to do that. I believe she misspoke or I misheard. But it did get my attention.?ÿ
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Wow- learn something new all the time. Never realized the horizon was cockeyed out there in the middle of the ocean. ?????ÿ
I think the image was really taken in microwave radio energy and reproduced in false color. They need the baseline known within a small fraction of a wavelength in order to properly combine the data from multiple observation points spread as far around the earth as practical. They get that by observing a known source in the sky and finding the delay needed to combine those observations, and then using those delays to process the signals from the unknown source.?ÿ They are correcting for the rotation of the earth all that time.?ÿ And it takes a huge amount of data averaging to pull out the image from the noise.
It is a little bit analogous to GNSS work where the satellite positions are determined from known earth stations and that lets you calculate the position of another point.
viewed from 55 million light-years away on Earth, the black hole is only about 42 microarcseconds across on the sky. That??s smaller than an orange on the moon would appear to someone on Earth.
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The wavelengths are assigned a color, it was explained that they are capturing sub millimeter bands, unlike earlier interferometry that used radio length wavelengths. The telescopes are connected in a network, and like you say are not located by GPS, also they need extremely exact time to accomplish capturing the image.
They were excited because the scientists predicted that the image would be a donut, with the center black and the ring split in 1/2 by a bright and a dimmer half, exactly as it was found to be. And they explained that no matter where you observe it, it will look the same. Someone in the audience asked if they can observe it from a different angle to prove their theory. The answer was they would need lots more money to do it.
something like a billionth of a meter.
I thought I read something like that on this board, once...
My thought was; who's going to prove you wrong?
Sixth pic looks like Hilo, third looks like north end of Hapuna??ÿ ?????ÿ
I was thinking the same.
These people are doing some serious measurements, not like us GPSers with our dopey GPS receivers. Imagine the closure when you are measuring between a telescope in the US, Hawaii, Europe, Chile and you are concerned with a billionth of a meter. That isn't done with OPUS.
@flga-pls-2-2
#1 and 2 are Hapuna, #3 is 69 beach, #4 is Spencer, #5 is Pololu, #6 is Waipio, where the river meets the sea, #7 is Makalawena, a brutal 4x4 ride, or a long hike, we drove there.
Seems like every other vehicle is a Wrangler or a Tacoma/4 Runner, half of those are lifted.
This is the other end of the Waipio Valley:
Not only in the middle of the ocean, but in the Inside Passage. A lot of my pics have a very similar tilt. Maybe it's the entire Pacific area.