Re: 82041C search elements

From: paul (astro@pgog.net)
Date: Wed Aug 14 2002 - 12:49:23 EDT

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    70001 02 226XXZ 8305 F 20020814104512000 97 35 0051185+350230 96 F
    70000 02 226XXX 8305 F 20020814104742250 97 35 0034407+347510 96 F
    
    ref ted's search elset, for KH 9-17 Elint 13172 82041C,
    I saw these 2 N->S UNID's this morning.  positions are rough due
    to circumstances beyond my control.  prelim analysis indicates
    that 1st pt was unrelated debris; 2d pt is possible
    match with pt seen west of me on next rev.  early ~ 5.7 mins.
    gee I cannot recall if I'm supposed to use search IDs or the real
    IDs in pts.  view not long enough to determine flash period.
    expect an update from ted re possible new search elset.
    
    At 13:14 8/11/2002 -0400, you wrote:
    >82041C has entered morning visibility in the N. Hemisphere. The latest
    >elements are 158 d old, so a search will required in order to resume
    >regular tracking. I intend to try to recover it in the coming days, but
    >in case anyone else would like to try, I offer the following
    >suggestions.
    >
    >I have produced the following search elements by reducing the rate of
    >decay of Mike McCants' latest elset, to reflect the decreased solar
    >activity of the past 158 d:
    >
    >KH 9-17 ELINT    0.3  0.9  0.0  6.5 v
    >1 70000U          02066.79004738  .00003875  00000-0  54519-3 0    02
    >2 70000  95.9590  83.3641 0003000 343.3469  16.6530 14.77431534    06
    >
    >I estimated the decrease by analogy with 84065C, a similar payload, in a
    >slightly lower orbit. I found that over about the same period, I had to
    >reduce 84065C's rate of decay by 35.4 percent in order to accurately
    >predict its recent passes, so I reduced 82041C's rate of decay by the
    >same percentage.
    >
    >I have used this method successfully in the past, but I caution that a
    >generous allowance still is required for prediction time uncertainty. I
    >suggest starting the first search 10 min early, and being prepared to
    >wait at least as long late.
    >
    >This object flashes about once per second, and its minima may be
    >invisible at high phase angle.
    >
    >Less allowance is required for Earth's rotation during the search
    >period, by observing at moderately low elevations, as long as the object
    >is likely to be sufficiently illuminated.
    >
    >Ideally, select a portion of the sky with a nice fence of stars
    >perpendicular to the predicted path, to provide maximum opportunity to
    >obtain an accurate position.
    >
    >For the recovery, even a rough position, i.e. "passed 1 deg below
    >Altair" timed to within a few seconds, would be very helpful. That would
    >enable the search orbit to be improved sufficiently to easily re-acquire
    >the object, to obtain precise positions.
    >
    >Ted Molczan
    >
    >
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