Raduga 27 dynamics

From: Matson, Robert (ROBERT.D.MATSON@saic.com)
Date: Tue Feb 22 2000 - 19:47:14 PST

  • Next message: Bjoern Gimle: "Re: ETS 6 Watch 2000 - predictions"

    Hi Jason,
    I analyzed 15 of your Raduga 27 flash observations dating
    back to May 9th of last year and came up with a spin axis
    of RA 17.0218 hrs, Dec +79.1773 deg, and a cone angle of
    86.568 degrees.  I suspect the actual cone angle is within
    a degree of 90 degrees, but more observations are needed
    to refine the axis.  Fortunately the precession of the
    axis would seem to be small, but another 4 months of data
    will be needed to quantify it with any accuracy.
    Since I didn't have peak flash times to work with, I used
    the midway points of your start and end times for each
    observation.  (This definitely introduces some error because
    the flash track is not moving symmetrically with respect
    to your location).
    If my analysis is in the least bit accurate, then flashes
    currently start in NE Africa around 15:40 UT, slowly working
    their way northward.  By 16:30, the southern-most portion
    of Saudi Arabia is reached.  17:15 - the border between
    Sudan and Egypt; Cairo about 30 minutes later.
    Crete and Sicily are crossed at 18:00, followed by Greece
    and Italy in the next 15 minutes.  The peak for southernmost
    France should be around 18:15, with Switzerland only 10
    minutes later.  London and Belgium are on the flash centerline
    at 18:32, Edinburgh at 18:40, and southernmost Sweden at
    18:45.  All these times are for Wednesday, Feb. 23rd UT.
    One problem with this analysis is that it assumes that the
    reference points I used are all associated with the same
    reflecting surface.  For example, if I use your observations
    from May 9th and June 4th, 1999, and Feb. 13th, 2000, I come
    up with a spin axis of RA 5.4566 hours, Dec -66.4579, and
    a cone angle of 81.2773.  This axis may turn out to be
    more accurate since it involves the brighter flashes you
    observed on the morning of the Feb 13th rather than the
    dimmer evening flashes.  More observations of the bright
    morning flash sequence (which is shorter lasting than the
    evening sequence) are needed to converge on the correct
    The morning sequence is visible from all of Africa, Europe,
    Scandinavia and some of western Russia.  Like the evening
    sequence, flashes begin in the south and work their way
    north (actually, more to the north-northeast).  For Thursday
    morning, Feb. 24 UT, flashes start at the southern tip of
    Africa around 0:00, and Cairo about 2 hours later.  Central
    France and Italy are on the centerline at 2:10, London at
    2:15, Belgium around 2:17, Edinburgh at 2:22, southern
    Norway/Sweden at 2:30, and southern-most Finland at 2:40.
    It will be nice to firm up the behavior of this satellite
    so that it can be regularly predicted like Superbird A.
    By the way, I'm still working on ETS-6... --Rob
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