RE: Beautiful ISS/Shuttle

From: Chris Peat (
Date: Mon Sep 18 2000 - 12:08:17 PDT

  • Next message: Daniel Deak: "Re: Beautiful ISS/Shuttle"

    Hi All,
    Jim Cook wrote:
    > By the way, someone mentioned that Heavens-Above had shown the
    > ISS leading.
    > I had checked the TLE it was using for Atlantis earlier this morning and
    > found its epoch date was 24 hours old, meaning it was valid for a
    > time when
    > the spacecraft were still docked.  I'm confused how that TLE
    > could have been
    > used for Atlantis's orbit AFTER undocking?  I could see doing
    > that for the
    > ISS, but it's the shuttle that changes orbit after undocking.  I
    > wonder if
    > they got them mixed up?
    Just to clarify how we update our TLEs at Heavens-Above.
    For Shuttle missions and other satellites which change their orbits
    frequently, we
    have an automated download
    procedure which gets the latest TLEs (defined in a favourites list) from OIG
    every 3 hours,
    so this is the maximum delay from our side.
    The main source of delay seems to be OIG updating their elsets, which can
    sometimes be over
    24 hours old even for the Shuttle. Even now, at 19:02 UTC, their latest
    elset epoch is
    10am UTC. I notice that their vector data has a much more recent elset, and
    I will try to automate
    download and conversion of this for future STS missions. Hope this clarifys
    By the way, work on the on-line observations database continues well, and I
    should have
    something ready soon.
    Chris Peat, Heavens-Above GmbH
    Web site:
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