Introducing Comet Leonard
Posted: Tue Nov 23, 2021 8:11 am
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Chiff and Fipple Forums
https://forums.chiffandfipple.com/
"He's your son!!" of APOD
https://forums.chiffandfipple.com/viewtopic.php?f=10&t=97469
Page 188 of 247
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Lunar Eclipse over a Skyscraper
Posted: Tue Nov 23, 2021 8:13 am
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The Sun in X-rays from NuSTAR
Posted: Tue Nov 23, 2021 8:14 am
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Re: "He's your son!!" of APOD
Posted: Thu Dec 02, 2021 7:05 pm
I believe the NuStar mirrors were the first made with a really cool technique. X-ray mirrors can only reflect at very grazing angles, so to increase the collection aperture, they nest a whole bunch of mirrors. Each mirror is very thin. They've generally been made with electroforming -- electroplate something like nickel or rhodium onto a stainless-steel mandrel and somehow separate the mirror from the mandrel.
These mirrors were made by placing a thin piece of glass on a heated mandrel and letting the glass sag till it takes on the shape of the mandrel. It's quicker and cheaper than electroforming, so they can make dozens of them and pick the best for the flight optics. I think this was also the first mission to use multilayer "super-mirror" coatings that increase the reflectance, especially at higher energies.
These mirrors were made by placing a thin piece of glass on a heated mandrel and letting the glass sag till it takes on the shape of the mandrel. It's quicker and cheaper than electroforming, so they can make dozens of them and pick the best for the flight optics. I think this was also the first mission to use multilayer "super-mirror" coatings that increase the reflectance, especially at higher energies.
Pleiades: The Seven Sisters Star Cluster
Posted: Fri Dec 03, 2021 9:43 am
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At the Shadow's Edge
Posted: Fri Dec 03, 2021 9:44 am
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Great Refractor and Lunar Eclipse
Posted: Fri Dec 03, 2021 9:45 am
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Messier 101
Posted: Fri Dec 03, 2021 9:47 am
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A High Cliff on Comet Churyumov-Gerasimenko
Posted: Fri Dec 03, 2021 9:49 am
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The Extraordinary Spiral in LL Pegasi
Posted: Fri Dec 03, 2021 9:51 am
A Blue-Banded Blood Moon
Posted: Fri Dec 03, 2021 9:54 am
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NGC 6822: Barnard's Galaxy
Posted: Fri Dec 03, 2021 9:56 am
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Comet Leonard and the Whale Galaxy
Posted: Fri Dec 03, 2021 9:57 am
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Iridescent by Moonlight
Posted: Mon Dec 06, 2021 8:04 am
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