T-IV B-30 - ascent visibility

From: Ted Molczan (molczan@rogers.com)
Date: Fri Apr 29 2005 - 01:50:24 EDT

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    Titan IV B-30 is scheduled to lift-off on 2005 Apr 30 at 00:50 UTC (Apr 29 at
    20:50 EDT). The duration of the window has not been announced.
    
    I have cooked up trajectory data to aid in observing the rocket's ascent up the
    east coast of North America. 
    
    Rocket scientists likely would have a good laugh at my estimates, but I hope
    that they will be sufficient to provide a rough idea of when and where to look.
    
    Users of Rob Matson's Skymap program, should copy the appended data into a *.trj
    file.
    
    Non-Skymap users, can download an Excel spreadsheet to compute azimuth and
    elevation during the ascent to orbit:
    
    http://satobs.org/seesat_ref/B-30/Titan_IV_B-30_look_angles.xls
    
    All you need do is enter the lift-off time, and your latitude and longitude. As
    downloaded, the file contains the latitude and longitude of Washington, D.C.,
    which you should replace with your latitude and longitude.
    
    The spreadsheet computes azimuth and elevation at 10 s time intervals. Azimuth
    is in degrees, clockwise from due north. Elevation is in degrees above the
    horizon. Negative values of elevation indicate that the vehicle is below the
    horizon.
    
    The trajectory data begins at T+2:30, about the time that the solid rocket
    motors burn out.
    
    Observers who have seen shuttle night-time ascents along the east coast, should
    not expect the Titan IV's exhaust to be as bright.
    
    For about 3 min after SRB burnout, the T-IVB's 1st stage will produce about
    550,000 pounds of thrust - about one third the total output of a shuttle's main
    engines.
    
    The T-IVB's 2nd stage ignites for nearly 4 min; however, it produces a little
    over 100,000 pounds of thrust - about 7 percent the total output of a shuttle's
    main engines.
    
    Assuming lift-off occurs near the scheduled time, the vehicle may be illuminated
    by sunlight for some portion of its ascent, which should make it easy to spot
    with the unaided eye. It could reach magnitude 1 or brighter.
    
    I estimate that it will climb out of Earth's shadow at about T+3:30. How long it
    remains in sunlight depends on how high it climbs. Since its trajectory and
    planned orbit are secret, I can only guess.
    
    I based the ascent trajectory on one of several possible target orbits,
    specifically, that of a Lacrosse radar imaging satellite, inclined 57 deg, and
    425 X 671 km. An ascent trajectory bound for that orbit, would remain
    illuminated throughout the powered ascent, after exiting the shadow at about
    T+3:30.
    
    In the event that the target orbit is much lower, then the vehicle may re-enter
    the shadow before the end of the powered ascent, in which case the vehicle would
    be illuminated only by its exhaust, which may not be visible with the unaided
    eye.
    
    Ted Molczan
    
    
    Data for use in Skymap trj file:
    
    From left to right, the four columns contain:
    
    - time since launch, seconds
    - latitude, deg N
    - longitude, deg E
    - altitude , km
    
    150 29.10 280.08 62
    160 29.15 280.15 68
    170 29.20 280.23 74
    180 29.26 280.31 80
    190 30.15 280.21 96
    200 30.24 280.28 111
    210 30.33 280.37 127
    220 30.42 280.45 143
    230 30.52 280.54 159
    240 30.63 280.64 174
    250 30.74 280.75 190
    260 30.86 280.86 199
    270 30.99 280.98 208
    280 31.12 281.11 217
    290 31.27 281.25 226
    300 31.42 281.39 235
    310 31.59 281.55 244
    320 31.76 281.71 253
    330 31.95 281.89 262
    340 32.15 282.08 271
    350 32.36 282.29 280
    360 32.58 282.51 289
    370 32.82 282.74 298
    380 33.07 282.99 307
    390 33.34 283.26 316
    400 33.62 283.55 325
    410 33.93 283.86 334
    420 34.25 284.19 343
    430 34.59 284.54 352
    440 34.95 284.93 361
    450 35.34 285.34 370
    460 35.75 285.78 379
    470 36.18 286.25 388
    480 36.64 286.76 397
    490 37.13 287.32 406
    500 37.64 287.91 415
    510 38.19 288.56 424
    520 38.77 289.25 433
    530 39.38 290.01 442
    540 40.02 290.82 451
    550 40.70 291.71 460
    560 41.42 292.68 469
    570 42.18 293.73 478
    
    
    
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