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> with 900 telescopes that by 2025 could watch the entire visible night sky I assumed the entire visible night sky included the Southern Hemisphere. But the di

> with 900 telescopes that by 2025 could watch the entire visible night sky I assumed the entire visible night sky included the Southern Hemisphere. But the diagram shows all the telescopes in one location. > the Argus telescopes will sit in a 10-meter-wide bowl, all aiming out a single skylightlike window in a dome. Over the course of the night, the bowl and telescopes will pivot slowly to follow the stars as Earth rotates. Huh, I was imagining telescopes watching the entire sky simultaneously. This sounds like it will see just a tiny part at a time. So a star could go nova and the system would only catch it if it happened to be facing the right part of the sky at exactly the right moment.

mturmon 4y ago
The FOV really is quite large -- the documents give it at 7900 square degrees. If you take that to be a square patch, it's about 90x90 degrees! And you can't have it all. I had assumed atmospheric path length would be a problem as the FOV extends toward the horizon, but other optical issues limit you before that. From the arXiv paper I linked nearby: > Angle-of-incidence effects: Commercially-available antireflection coatings have a restricted range of effective angles of incidence, and this places an effective upper limit of 100◦–120◦ on the field of view of an array looking though a single window. The Argus Array’s Key Projects’ requirements easily conform to these limits, especially with the acceptance of slightly increased light losses for telescopes at the edge of the array. In other words, our FOV is about 90 degrees wide, and the coatings are OK to 100-120 degrees.
- irrational 4y ago
  So it sounds like we need a bunch of these all over the globe to actually watch the entire visible night sky.
spaetzleesser 4y ago
I guess during the night you also have the earth rotate quite a bit so you get a bigger field of view. For full coverage you need a few of them all over the world. Considering its price this should be quite doable.
klyrs 4y ago
Think about looking out of a small window. By moving around, you can change the angle of your line of sight. In the ultimate limit, you can almost see the outside wall. Rather than moving the viewer around, this array has lots of cameras pointing at the window from different angles.

mturmon 4y ago

The FOV really is quite large -- the documents give it at 7900 square degrees. If you take that to be a square patch, it's about 90x90 degrees! And you can't have it all. I had assumed atmospheric path length would be a problem as the FOV extends toward the horizon, but other optical issues limit you before that. From the arXiv paper I linked nearby: > Angle-of-incidence effects: Commercially-available antireflection coatings have a restricted range of effective angles of incidence, and this places an effective upper limit of 100◦–120◦ on the field of view of an array looking though a single window. The Argus Array’s Key Projects’ requirements easily conform to these limits, especially with the acceptance of slightly increased light losses for telescopes at the edge of the array. In other words, our FOV is about 90 degrees wide, and the coatings are OK to 100-120 degrees.

irrational 4y ago
So it sounds like we need a bunch of these all over the globe to actually watch the entire visible night sky.

spaetzleesser 4y ago

I guess during the night you also have the earth rotate quite a bit so you get a bigger field of view. For full coverage you need a few of them all over the world. Considering its price this should be quite doable.

klyrs 4y ago

Think about looking out of a small window. By moving around, you can change the angle of your line of sight. In the ultimate limit, you can almost see the outside wall. Rather than moving the viewer around, this array has lots of cameras pointing at the window from different angles.