NROL-24: updated search elements

From: Ted Molczan (
Date: Sun Dec 09 2007 - 17:20:24 UTC

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    NROL-24 is scheduled for launch on 2007 Dec 10 at 22:04 UTC:
    Here are updated search elements, assuming an on-time launch, and the same
    trajectory as the previous similar launch, NROL-1:
    1 79000U          07344.96707176  .00000000  00000-0  00000-0 0    00
    2 79000  57.3981 310.1593 0001000 113.4954 176.8000 16.05000000    05
    1st ascending node
    1 79001U          07344.97850452  .00017925  00000-0  14828-2 0    07
    2 79001  57.3981 310.1520 5327478 293.4985  20.3013  5.13214280    05
    The ascent trajectory will be north-eastward along the east coast of North
    America, not long after sunset. I had planned to produce estimated ascent look
    angles, but have had to cancel for personal reasons.
    Visual observers in and near North America's eastern time zone may be able to
    observe the Centaur's propellant dump soon after MECO2, as occurred with NROL-1
    in August 2004, which was widely observed from eastern North America.
    Steve Newcomb spotted it with his unaided eye about 1h 38m after launch:
    I spotted it minutes later, also with my unaided eye. It was a slow-moving
    luminous cloud, about the diameter of the moon, in an otherwise clear sky:
    Fellow Torontonian, Eric Briggs made a video revealing the complex shape of the
    To attempt to observe this event, run an ephemeris for your location using the
    79001 elset above. Based on NROL-1, and assuming an on-time launch, the dump
    should already be in progress and visible by 23:42 UTC (18:42 EST).
    CAUTION: Both the orbit and the timing of the dump are somewhat uncertain, due
    to NROL-24's use of a different launch vehicle than NROL-1. As a result,
    ephemerides made using the above search elements could easily be off by at least
    5 deg in position, and quite a few minutes in time, so it is best to scan along
    the predicted track with the unaided eye. The timing of the dump is also
    somewhat uncertain, so I recommend allowing at least +/- 10 min.
    Once the cloud has been spotted, large binoculars or a telescope will reveal the
    complex shape of the cloud, and the Centaur and possibly the payload may be
    visible near its apparent point of origin.
    Accurately timed still and motion imagery showing the cloud relative identified
    stars would be appreciated, for the purpose of orbit determination. Weather
    permitting, I will attempt to make precise visual observations.
    Ted Molczan
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