Delta IV/DMSP Launch Observation

From: Brian Webb (kd6nrp@earthlink.net)
Date: Sat Nov 04 2006 - 12:39:40 EST

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    Hello:
    
    I observed the Delta IV/DMSP F-17 launch this morning from Vandenberg AFB.
    My site was a hill in Ventura County, California* located about 95 statute
    miles east-southeast of the launch site.
    
    The sky was clear, but not very dark due to the approaching sunrise. I
    didn't expect the launch to occur today because of the pessimistic launch
    weather forecast issued yesterday. At about 05:53 PST (13:53 UTC) one of the
    other observers said "There it is." Sure enough, there was a distant, but
    faily bright spot of light on the horizon.
    
    Although official sources said this vehicle had no solid starp-on motors, it
    left a fairly thick, white trail for about 20 seconds that was similar to
    solid motor exhaust.
    
    After the trail disappeared, the vehicle continued to climb and I was
    surprised how bright it was. At about T+45 seconds the Delta IV was clearly
    much brighter than Venus when that planet is at its brightest. The vehicle's
    flame was at least magnitude -6 and more likely -8 (possibly even brighter).
    Although the first stage engine burns liquid fuel and oxidizer, it produced
    a flame as bright as a solid fuel missile like a Peacekeeper. In addition to
    the flame's brightness, I was also impressed by its orange color (hydrogen
    produces an orange flame, so this is likely due to the Delta IV's hydrogen
    fuel).
    
    The vehicle continued to cross the sky towards the south. At about T+60
    seconds there was a hint of a very tenuous exhaust plume behind the Delta
    IV.
    
    Several seconds later, a very brief, bright, wedge-shaped exhaust plume
    appeared. The plume was white in color and lasted no more than 2 or 3
    seconds. This was probably caused by stage 1/stage 2 staging.
    
    The Delta grew fainter, but it still easily visible against the semi-bright
    sky background. About that time, I took a photo that shows the Delta passing
    near the star Sirius. The rocket was about one full magnitude magnitude
    fainter than Sirius.
    
    As expected, the Delta IV launch produced an odd, luminous white cloud. I
    saw such a cloud during the last June's Delta IV launch and thought it was
    created by staging. However, June's cloud was high in the south but this
    morning's cloud was in the west (a totally different part of the sky than I
    had anticipated).
    
    At no time did the flame from this morning's Delta IV launch have a shape.
    It resembled a compact (but not star-like), bright blob.
    
    Four other observers showed up this morning to observe the launch. I don't
    recall having met any of them before.
    
    Regards,
    
    Brian Webb
    www.spacearchive.info
    
    * This viewing site is located at 34 17 57" (34.29917) N, 118 51 25
    (118.85694) W, elevation: 807 ft (246 M).
    
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