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<blockquote style="position: relative; padding-left: 55px;"><section><a href="https://astrodon.social/users/kellylepo/statuses/113853738167221633">Kelly Lepo (kellylepo@astrodon.social)'s status on Tuesday, 21-Jan-2025 01:35:04 JST</a><a href="https://astrodon.social/@kellylepo" title="kellylepo@astrodon.social"><img src="https://gnusocial.jp/avatar/28639-48-20221116180105.webp" width="48" height="48" alt="Kelly Lepo" style="position: absolute; left: 0; top: 0;">Kelly Lepo</a><div><a href="https://astrodon.social/@kellylepo/113853738150192595" rel="in-reply-to">in reply to</a></div></section><article><p>Degree Angular Scale Interferometer at the South Pole made observations of the CMB power spectrum in 1999-2000, a measurement of the size of the fluctuations in the cosmic microwave background in the sky. </p><p>These results agreed with the Lambda CDM model of the universe and required the presence of dark matter. The next season they returned and got polarization measurements.</p></article><footer><a rel="bookmark" href="https://gnusocial.jp/conversation/4411031#notice-8629065">In conversation</a><time datetime="2025-01-21T01:35:04+09:00" title="Tuesday, 21-Jan-2025 01:35:04 JST">about 4 months ago</time> <span>from <span><a href="https://astrodon.social/@kellylepo/113853738167221633" rel="external" title="Sent from astrodon.social via ActivityPub">astrodon.social</a></span></span><a href="https://astrodon.social/@kellylepo/113853738167221633">permalink</a><h4>Attachments</h4><ol><li><label><a rel="external" href="https://gnusocial.jp/attachment/3968305">DASI
Degree Angular Scale Interferometer at the South Pole
Image of the telescope at the south pole. A series of metal tubes sticks out of a flat metal box with a rounded bottom. It is surrounded by a semi-circular metal baffle, covering the ground. In the background is white snow and some far-off buildings.
DASI refractive "telescope" with 26-36GHz HEMT receiver. An instrument made out of metal cylindrical parts.
Cosmic Background Imager "sister" instrument to DASI (Tony Readhead, Steve Padin, et al.) A series of cylinders sits on metal scaffolding, angled to point at the sky. In the background are mountains and a blue sky.</a></label><br><a href="https://media.astrodon.social/media_attachments/files/113/853/200/634/887/940/original/1e10a2a09aa89842.png" rel="external">https://media.astrodon.social/media_attachments/files/113/853/200/634/887/940/original/1e10a2a09aa89842.png</a></li><li><label><a rel="external" href="https://gnusocial.jp/attachment/3968306">DASI 1st season results
Maps: Grid of circles with blue, red, and green blobs.
Angular Power Spectrum: Plot of the angular power vs. multipole (l). The COBE measurement is on the far left, blue points from DASI fill in the other bumps and wiggles.
The numbers:
Vu-graph from 2001
Weak h prior, h&gt; 0.45 and Tau_L &lt;= 0.4
Ω_TOTAL = 1.04±0.06
Ω_B h^2= 0.022 +0.004 - 0.003
Ω_CDM h^2 = 0.14±004
requires dark matter
n_s = 1.01 +0.08 -0.06
Strong h prior, h=0.72±0.08 and Tau_L &lt;=0.4
Ω_TOTAL =  1.00 ±0.04
Ω_M  = 0.40 ± 0.15
Ω_Lambda= 0.60 ±0.15</a></label><br><a href="https://media.astrodon.social/media_attachments/files/113/853/200/793/987/599/original/d453705ae5403dab.png" rel="external">https://media.astrodon.social/media_attachments/files/113/853/200/793/987/599/original/d453705ae5403dab.png</a></li><li><label><a rel="external" href="https://gnusocial.jp/attachment/3968307">DASI 2nd season results → CMB Polarization
Map of a section of the esky showing red and yellow blobs. On top of this is a grid of small lines indicating the polarization direction.
Plot showing the DASI data. It forms a bell curve, which overlaps with the theory prediction.• Worked great. Further supported the ACDM cosmological model.
• But to go forward we needed much more throughput ...
Cover of Nature featuring an image of DASI - Pattern in the cosmos.</a></label><br><a href="https://media.astrodon.social/media_attachments/files/113/853/201/670/333/582/original/4a5f3fafe9883272.png" rel="external">https://media.astrodon.social/media_attachments/files/113/853/201/670/333/582/original/4a5f3fafe9883272.png</a></li></ol></footer></blockquote>

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Kelly Lepo (kellylepo@astrodon.social)'s status on Tuesday, 21-Jan-2025 01:35:04 JST Kelly Lepo
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Degree Angular Scale Interferometer at the South Pole made observations of the CMB power spectrum in 1999-2000, a measurement of the size of the fluctuations in the cosmic microwave background in the sky.
These results agreed with the Lambda CDM model of the universe and required the presence of dark matter. The next season they returned and got polarization measurements.
In conversationabout 4 months ago from astrodon.socialpermalink
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