Update on Unknowns

From: Greg Roberts (grr@telkomsa.net)
Date: Fri Dec 26 2008 - 08:33:08 UTC

  • Next message: Russell Eberst: "2008DEC25.OBS"

    Xmas is not the time to track a lot of satellites !
    
    Now have a lot of catching up and measuring to do.
    
    Herewith info not reported before.
    
    On 21 Dec 2008 found a very bright (10th magnitude) satellite and got
    several positions as follows:
    
    
    21 Dec 2008
    New BRIGHT geo #91131:
    -----------------------------------
    91131 08 856GEO 0433 G 20081221190534000 56 15 0326066+052552 39  +100 05
    91131 08 856GEO 0433 G 20081221192122000 56 15 0341560+052531 39  +100 05
    91131 08 856GEO 0433 G 20081221205324000 56 15 0514020+052303 39  +100 05
    
    
    Due to bad weather I was unable to observe again until the 24th December
    when I again found #91131 further west. In the meantime I had updated my
    satellite database which showed the object was in fact ASTRA 1M. On year
    day 8352 the orbital period was 1.002714, yet the next set of elements
    with YD 08357 showed the orbital period was 1.00124475 so ASTRA 1M is
    being moved westward, so object #91131 is NO longer an unknown.
    
    In the process of looking for #91131 on the 24th December a faint
    geostationary was found and observed as below:
    
    24 Dec 2008
    
    UNKNOWN #91132 :
    -------------------------------
    91132 08 859GEO 0433 E 20081224202334000 56 15 0434267+052646 39  +125 05
    91132 08 859GEO 0433 E 20081224202600000 56 15 0436515+052656 39  +125 05
    91132 08 859GEO 0433 E 20081224202952000 56 15 0440431+052729 39  +125 05
    91132 08 859GEO 0433 E 20081224203344000 56 15 0444342+052732 39  +125 05
    91132 08 859GEO 0433 E 20081224203517000 56 15 0446061+052749 39  +125 05
    91132 08 859GEO 0433 E 20081224213954000 56 15 0550382+053156 39  +120 05
    91132 08 859GEO 0433 E 20081224214320000 56 15 0554043+053158 39  +120 05
    91132 08 859GEO 0433 E 20081224214736000 56 15 0558216+053213 39  +115 05
    91132 08 859GEO 0433 E 20081224215153000 56 15 0602373+053250 39  +115 05
    91132 08 859GEO 0433 E 20081224215519000 56 15 0606026+053246 39  +115 05
    91132 08 859GEO 0433 E 20081225004743000 56 15 0858136+054056 39  +125 05
    91132 08 859GEO 0433 E 20081225005514000 56 15 0905426+054121 39  +125 05
    
    Notes:
    -------
    
    (1) The object above is relatively difficult - with no elements it took
        quite a bit of effort to decide what was a satellite and what was a
        dead pixel/image defect etc but Im reasonably confident of the above
        which was observed over three spells.
    
        The first one- starting at 20h23m34s UT had the satellite reasonably
        steady at about magnitude +12.5 with perhaps a very small variation
        in magnitude.
    
        The second session ,starting at 21h39m54s was easy and no trouble
        spotting the satellite.
    
        The third session starting at 00h47m43sUT 25 Dec was difficult again
        with the satellite appearing to show a bigger variation in magnitude.
        At brightest was about mag +12.5 to +13 but was invisible on most
        frames  ( see Scotts comment later - this observation was either a
        different object or more likely just image defects)
    
    
    Scott produced elements from the above and with this information I
    re-examined images taken on the 21st December and found the object again
    as below:
    
    21 Dec 2008
    UNKNOWN #91132:
    ---------------------------
    91132 08 859GEO 0433 E 20081221191301000 56 15 0327553+052203 39  +130 05
    91132 08 859GEO 0433 E 20081221191506000 56 15 0330014+052203 39  +130 05
    
    Notes:
    ------
    (1) This may be the same object tracked on the 24/25 December 2008. It is
        even fainter than the other observations. It does not appear to be a
        dead pixel but if it screws up everything then ignore - this is a
        "desperate" attempt to try and salvage whatever I got on the 21st Dec.
    
    Using the observations from 21 Dec and 24 Dec Ted derived the following
    orbit:
    
    "The following SGP4 (not SDP4) elements fit Gregs Dec 21 and 24 UTC obs
    with low residuals:
    
    1 91132U 08859GEO 08359.84430206  .00000000  00000-0  00000-0 0    01
    2 91132   0.1795  65.4646 0002121 209.6614 150.3265  0.99949280    07 "
    
    Scott derived the following orbit:
    
    1 91132U 000000   08356.80215278 0.00000000  00000-0  50000-4 0    03
    2 91132   0.0499 170.6727 0001325 206.7938  33.3372  0.99948368    03
    
    
    91132 08 859GEO 0433 E 20081221191301000 56 15 0327553+052203 39  +130 05
    91132 08 859GEO 0433 E 20081221191506000 56 15 0330014+052203 39  +130 05
    91132 08 859GEO 0433 E 20081224202334000 56 15 0434267+052646 39  +125 05
    91132 08 859GEO 0433 E 20081224202600000 56 15 0436515+052656 39  +125 05
    91132 08 859GEO 0433 E 20081224202952000 56 15 0440431+052729 39  +125 05
    91132 08 859GEO 0433 E 20081224203344000 56 15 0444342+052732 39  +125 05
    91132 08 859GEO 0433 E 20081224203517000 56 15 0446061+052749 39  +125 05
    91132 08 859GEO 0433 E 20081224213954000 56 15 0550382+053156 39  +120 05
    91132 08 859GEO 0433 E 20081224214320000 56 15 0554043+053158 39  +120 05
    91132 08 859GEO 0433 E 20081224214736000 56 15 0558216+053213 39  +115 05
    91132 08 859GEO 0433 E 20081224215153000 56 15 0602373+053250 39  +115 05
    91132 08 859GEO 0433 E 20081224215519000 56 15 0606026+053246 39  +115 05
    91132 08 859GEO 0433 E 20081225004743000 56 15 0858136+054056 39  +125 05
    91132 08 859GEO 0433 E 20081225005514000 56 15 0905426+054121 39  +125 05
    
    
          STA  YYday HHMM:SSsss   AZ     EL     ASP     XTRK   deltaT  Perr
    ( 1) 0433  08356 1913:01000   22.3   48.5   91.8    0.03    0.92   0.029
    ( 2) 0433  08356 1915:06000   22.3   48.5   91.8    0.03   -0.27   0.029
    ( 3) 0433  08359 2023:34000   16.4   49.5   91.3    0.01   -3.93   0.020
    ( 4) 0433  08359 2026:00000   16.4   49.5   91.3    0.01   -2.85   0.015
    ( 5) 0433  08359 2029:52000   16.4   49.5   91.3    0.00   -2.63   0.011
    ( 6) 0433  08359 2033:44000   16.3   49.5   91.3    0.00   -1.91   0.008
    ( 7) 0433  08359 2035:17000   16.3   49.5   91.3   -0.00   -0.88   0.005
    ( 8) 0433  08359 2139:54000   16.2   49.5   91.3   -0.05    0.89   0.052
    ( 9) 0433  08359 2143:20000   16.2   49.5   91.3   -0.05    0.62   0.052
    (10) 0433  08359 2147:36000   16.2   49.5   91.3   -0.05   -0.90   0.055
    (11) 0433  08359 2151:53000   16.2   49.5   91.3   -0.06    0.18   0.064
    (12) 0433  08359 2155:19000   16.2   49.5   91.3   -0.06    0.71   0.062
    (13) 0433  08360 0047:43000   15.9   49.4   91.3   -0.16    4.15   0.160
    (14) 0433  08360 0055:14000   15.9   49.4   91.3   -0.16    5.69   0.166
    
    Scott wrote:
    
    "Hi Greg,
    
    Notice that obs (13) and (14) have different cross track residuals..so
    I don't think they go with the rest.
    
    This is a good elset for the 12 obs
    
    1 91132U 000000   08359.86365470 0.00000000  00000-0  00000+0 0    02
    2 91132   0.1696  73.6968 0010304 106.7292 252.1101  0.99952721    00 "
    
    So object #91132 has a reasonably good element set which can hopefully
    be refined by further observations.
    
    Update on Unknowns #91133,91134 and 91135:
    ----------------------------------------------------------
    
    The first two appear to be in a drifting orbit. One of them MAY be
    INMARSAT 3F1 which was not seen at its normal position so it may be
    moving westward.
    
    #91135 appears to be a high eccentricity object with inclination around
    22 degrees. I am not going to make any special effort to try and recover
    this again. It would appear to be debri of some sort.
    
    I plan to track tonight - 26th December - if clear - in an attempt to
    further refine the orbits for #91132,#91133 and #91134 despite having
    a large backlog still to do from my observing session on 24th December
    which I will be working on the rest of today.
    
    
    Cheers
    Greg
    
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