DM-F3 / Delta 3 RB - Who is Who ?

From: Ron Lee (
Date: Sun Aug 27 2000 - 04:05:10 PDT

  • Next message: "Mir 8/26"

    This morning around 1030 UT (27 Aug 2000) I observed both
    objects from the recent Delta III launch.  Elsets used below.
    Note I will use the NORAD # as specified in these elsets, not
    necessarily the correct ID as Mr Zimmer postulated yesterday.
    DM-F3                                            20631 x 188 km
    1 26475U 00048A   00239.36891453  .00110183  77807-6  25976-2 0    91
    2 26475  27.6333 309.7374 6088593 176.2641 192.2463  3.99173289   119
    DM-F3 Delta 3 r                                  20637 x 186 km
    1 26476U 00048B   00239.11586436  .00003254  77957-6  84746-4 0    73
    2 26476  27.6082 309.1530 6090299 176.5940 191.2062  3.99105841   102
    First to appear was #26476, the "rocket."  It was on time/track and 
    appeared steady during the approximately two minutes that I observed it.
    Then the thin clouds hovering around moved in but I still picked up
    object #26475, the "payload."
    I was still able to track it and noticed a fluctuation.  Could have 
    been due to clouds.  Another dimming and I started my stopwatch.
    After several more such events I lost it in the clouds.  The satellite
    would stay at about the same magnitude, then dim for a few seconds
    then quickly brighten.  I timed the dim part when I should have timed 
    the brightening.  Still I got 39.7, 41.3, 35.6 and 42.3 intervals.
    Considering the uncertainty in my timing method I place this as certain
    rotation of the supposed payload.  Thus I would have to agree with Harro
    that the current identification of the two objects are swapped.
    The payload was about the same magnitude as the rocket but this estimate
    is possibly skewed by the clouds.
    The only improvement I could make in this obs is track the likely real
    payload for a longer period to verify it is not dimming.  But as Harro
    stated, it is unlikely to change more than 0.2 magnitude which I might
    not detect.  The dimming of the probable real rocket was to invisibility
    thus about 1.5 magnitude or more.
    Ron Lee
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    This archive was generated by hypermail 2b29 : Sun Aug 27 2000 - 04:05:33 PDT