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NSF-Swift / satellite-overhead

An open-source tool for calculating satellite interference to radio astronomy observations.
https://pypi.org/project/sopp/
GNU Affero General Public License v3.0
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Bump Skyfield dependency from 1.45 to 1.47. #105

Closed 0xeb-bp closed 10 months ago

0xeb-bp commented 10 months ago

Bump the required version of Skyfield to 1.47 which updates Skyfield’s internal table for the ∆T Earth orientation parameter so that its predictions now extend to 2025-01-18.

KevinKGifford commented 10 months ago

Does this imply that downloaded TLEs would be valid for several months?

From: 0xeb-bp @.> Sent: Monday, January 22, 2024 15:29 To: NSF-Swift/satellite-overhead @.> Cc: Subscribed @.***> Subject: [NSF-Swift/satellite-overhead] Bump Skyfield dependency from 1.45 to 1.47. (PR #105)

Bump the required version of Skyfield to 1.47 which updates Skyfield’s internal table for the ∆T Earth orientation parameter so that its predictions now extend to 2025-01-18.

You can view, comment on, or merge this pull request online at:

https://github.com/NSF-Swift/satellite-overhead/pull/105

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(1 filehttps://github.com/NSF-Swift/satellite-overhead/pull/105/files)

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0xeb-bp commented 10 months ago

Skyfield carries recent IERS data in internal tables. Skyfield periodically releases a new version to update these tables. It is explained in more detail here: https://rhodesmill.org/skyfield/time.html#ut1-and-downloading-iers-data

An alternative approach is to fetch the latest IERS data instead of relying on Skyfield's internal tables. However, a potential issue is the intermittent availability of the FTP server hosting this data. As an illustration, the server is currently inaccessible.

nikojpapa commented 10 months ago

Does this imply that downloaded TLEs would be valid for several months?

I think this does not affect the downloaded TLEs. Those are provided/downloaded separately. This would be for calculations done by the Skyfield package itself during its calculations.