Upcoming NOSS launch on Atlas 3B

From: Ted Molczan (molczan@rogers.com)
Date: Tue Feb 01 2005 - 14:46:16 EST

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    Spaceflight Now reports that an Atlas 3B is scheduled to lift off from CCAFS on
    2005 Feb 03 at 07:41 UTC (2:41 AM EST):
    
    http://www.spaceflightnow.com/atlas/ac206/status.html
    
    Observers in parts of North America can look forward to a couple of rarely seen
    events: the ascent trajectory, and the Centaur upper stage's propellant dump,
    both of which are discussed below.
    
    I believe that the payload is a pair of NOSS 3 satellites, to augment those
    launched in 2001 Sep and 2003 Dec:
    
    http://www.satobs.org/noss.html#NOSS3
    
    Here are search elements, in 2-line format:
    
    MES2                                                   1010 X 1208 km
    1 70999U          05034.37193286  .00000000  00000-0  00000-0 0    08
    2 70999  63.4167 155.0000 0132437 179.7272  98.8000 13.39694040    03
    
    Description of 2-line elements: http://www.satobs.org/element.html
    
    I expect predictions within 24 h of launch, based upon these elements, will be
    accurate to within about 5 min of time, and a few deg of arc, but I offer no
    guarantee.
    
    The epoch of the above corresponds to the start of MES2 (main engine start #2),
    the very brief final burn of the Centaur upper stage, which mainly raises the
    perigee to its required altitude.
    
    Planar NOSS launch windows arrive 14 min earlier for each day of any launch
    delay. The weather forecast for the Feb 3 launch window is poor, so a delay is a
    distinct possibility.
    
    After deployment, the payloads will gradually fall behind the Centaur; all three
    objects are best seen using 7x50 binoculars.
    
    Observers in parts of North America can look forward to a couple of rarely seen
    events. The first, is the ascent trajectory, which will track toward the
    northeast, off the east coast of the U.S.A. and Canada. I am aware of work in
    progress to generate a trajectory (*.trj) file for use with Rob Matson's Skymap
    program. The program is available via this web page:
    
    http://www.satobs.org/orbsoft.html#IBM
    
    It is my hope that the trajectory data will be posted to SeeSat-L sometime
    tonight or tomorrow. For the benefit of casual observers and those not
    experienced in the use of Skymap, I intend to generate some look angles for a
    few major cities near the east coast.
    
    The second rarely seen event is the Centaur's propellant dump, which if
    illuminated by the sun, results in a large, glowing cloud, readily visible to
    the unaided eye, even at distances of tens of thousands of kilometres. 
    
    The exact time of the dump has not been published; however, based upon typical
    practice, it should be completed by about 2350 s after MECO2, which on Feb 3
    occurs near 09:35 UTC. That would put the dump within Earth's shadow; however,
    it would pass into sunlight about 4 min later, 09:39 UTC, near 53 N, 82 W,
    altitude 1161 km, becoming visible to observers in the northeast. A cursory look
    indicates visibility at least as far west as Chicago, and at least as far south
    as Washington D.C.
    
    The Centaur propellant dump from the Atlas 2AS launched on 2004 Aug 31 UTC, was
    visible to the unaided eye at ranges in excess of 8000 km, for about 10 min
    after it ended. I spotted it while in progress, at a range of about 6300 km, as
    a glowing cloud about the apparent diameter of the moon. Binoculars revealed
    considerable structure in the plume.
    
    To assist as many people as possible to see this event, Heavens-Above kindly has
    agreed to host a copy of the above search element set, which will be updated in
    the event of launch delays. To run your own predictions, go to this page:
    
    http://www.heavens-above.com
    
    select or enter your site co-ordinates, then from the main page, click "Select a
    satellite from the database", and enter 70999 in the box labelled "US Space
    Command ID", and follow the instructions to generate custom pass predictions. Be
    careful to ignore predictions for dates and times prior to lift-off.
    
    Ted Molczan
    
    
    
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