1992- 30 J accelerating?

From: Leo Barhorst (leobarhorst@zonnet.nl)
Date: Sun May 21 2000 - 05:48:53 PDT

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    Has 1992- 30 J been accelerating and is now back on "normal"
    behavior??
    
    The latest observations of 1992- 30 J prompted me to do a kind
    of search in the TLE's to see if a MM-jump did occur that could
    explain the sudden accelerating of the period. I used the recently
    obtained TLE-Archive on CD-ROM from Allen Thomson to do the
    search. What a wealth of info!
    
    In 1999 I made the last observations of 1992- 30 J (21984) in april:
    
    92- 30 J 99-02-13 19:43:21   LB  171.4 0.5   2 85.7   AA, mag 4->7
    92- 30 J 99-02-14 03:55:30   LB  177.8 0.5   2 88.9   AA, mag 4->inv
    92- 30 J 99-04-01 21:35:22   LB  173.2 0.5   2 86.6   AA, mag 4->inv
    92- 30 J 99-04-12 20:53:17   LB   90.3 0.5   2 45.2   AA, mag 5->inv
    It was in a slow tumble; the last obs being seen as half period. There
    are no indications in the TLE's that a MM-jump occured in april 1999.
    
    More than a year later I decided to take a look againand to my sur-
    prise it was flashing much quicker. Following it over the next days
    showes clearly an acceleration.
    
    92- 30 J 00-05-05 23:29:30   LB   81.8 0.5   7 11.7   AA, 6->i
    92- 30 J 00-05-06 01:28:05   LB  104.3 0.5   9 11.6   AA, 5->i
    92- 30 J 00-05-12 22:30:33   LB   84.1 0.5  10  8.4   AA, 5->i
    92- 30 J 00-05-13 22:02:10   LB   81.9 0.5  10  8.2   AA, 5->i
    92- 30 J 00-05-20 21:01:01   LB   73.3 0.2  10  7.33  FF, 5->i
    
    When plotted with Satflash it seems that the minimum has already
    occurred between May 13 and 20 as the slope of the trendline
    is decreasing. With more observations in the next days it can be
    told for sure; or that the miniumum is still to come.
    
    Looking at the TLE's in the TLE-Archive on CD-rom the Mean Motion
    (MM) shows a gradual increase during 1999 and the first part of 2000.
    On 2000 day 00002 it was 12.22109247; reaching a maximum of
    12.22109850 on day 32. Further fluctuating slightly and going up again
    on day 56, reaching 12.22109817 on day 72.
    Then the rate increases more rapidly, see table below.
    Day 2000    MM
    00081        12.22110242
    00104        12.22111413
    00106        12.22112359
    00108        12.22121737
    00110        12.22130153
    00111        12.22131354
    00114        12.22133697
    00115        12.22134587
    00117        12.22138570
    00118        12.22139123
    00119        12.22139428
    
    From OIG I still had the following data:
    00126        12.22140293
    00132        12.22134898
    00137        12.22131393
    00138        12.22130708
    00139        12.22130608
    00141        12.22130909
    
    So it seems that around day 107 something happend to 1992- 30 J;
    and also around day 116, but smaller.
    From the latest elsets it seems to go up again till day 139 and then
    MM is increasing again.
    
    Perhaps Kurt Jonckheere can find some time to do a MM analyses,
    as he used to do in the past.
    I've requested historical TLE's from OIG for the period April 1st till
    present.
    
    Concluding:
    1992- 30 j is an object to be watching closely and observe on every
    oppurtunity. More accelerations are possible.
    
    
    Greetings and clear, dark skies
    Leo Barhorst
    52.767 N  5.09 E  2 m ASL
    
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