Obs 02 August-Messenger flyby

From: Greg Roberts (grr@iafrica.com)
Date: Wed Aug 03 2005 - 15:19:23 EDT

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    Observations 02 Aug 2005:
    ----------------------------
    
    Cosatrak 1 (Computerised satellite Tracking System).
    MINTRON low light level CCD surveillance camera (0.005 lux typical
    in non integration mode) and 0.00005 lux in STARLIGHT mode with 128
    frame integration.
    
    Used with 145mm focal length f/2.5 lens,integrating for 64 frames
    giving an equivalent exposure of 1.22 seconds.
    
    Site 0433 : Longitude 18.51294 deg East, Latitude  33.94058 deg S,
    Elevation 10 metres - situated in Pinelands (Cape Town), South Africa
    
    Messenger flyby:
    ----------------
    
    28391 04 030A   0433 P 20050802193949600 56 15 1803287+345046 39  +075 05
    28391 04 030A   0433 P 20050802194149600 56 15 1750163+311437 39
    28391 04 030A   0433 P 20050802194249700 56 15 1744224+293010 39
    28391 04 030A   0433 P 20050802194349800 56 15 1738534+275120 39
    28391 04 030A   0433 P 20050802194450000 56 15 1733466+261516 39
    28391 04 030A   0433 P 20050802194550200 56 15 1728590+244217 39
    28391 04 030A   0433 P 20050802194650300 56 15 1724308+231407 39
    28391 04 030A   0433 P 20050802194750500 56 15 1720196+214921 39
    28391 04 030A   0433 P 20050802194849700 56 15 1716287+202934 39
    28391 04 030A   0433 P 20050802194939700 56 15 1713236+192359 39
    28391 04 030A   0433 P 20050802195108900 56 15 1708096+173409 39
    28391 04 030A   0433 P 20050802195213600 56 15 1704389+161706 39
    28391 04 030A   0433 P 20050802195320800 56 15 1701111+150209 39
    28391 04 030A   0433 P 20050802200259600 56 15 1638030+062213 39
    28391 04 030A   0433 P 20050802200634300 56 15 1631398+035424 39
    28391 04 030A   0433 P 20050802201046400 56 15 1624574+012440 39
    28391 04 030A   0433 P 20050802201158900 56 15 1623131+004520 39
    28391 04 030A   0433 P 20050802201649600 56 15 1616528-013639 39
    28391 04 030A   0433 P 20050802202326100 56 15 1609346-041707 39
    28391 04 030A   0433 P 20050802202817200 56 15 1605010-055753 39  +105 05
    28391 04 030A   0433 P 20050802203046900 56 15 1602511-064319 39  +108 05
    28391 04 030A   0433 P 20050802203205800 56 15 1601476-070635 39  +130 05
    
    Notes:
    -------
    (1) Thanks to Mike McCants for notifying me and supplying me with
        predictions from the JPL Horizons On-line Ephemeris System
        I was able to observe the earth flyby of the Messenger space
        craft on its way to Mercury (eventually).
    
    (2) Despite heavy cloud I was able to see the earlier part of the
        flyby at a reasonable distance, the range being about 11300
        kilometres at start and reaching approximately 29000 kilometres
        when I lost it and was stopped by rain. The object appeared
        steady in brightness and was "spot-on"predictions, so much so
        that I could let the CoSaTrak system track solely on predictions
        and get occassional few second "gaps" in the clouds.
    
    (3) Something "odd" happened just after the 20h30m46.9s UT observation.
        Up to this stage the object had appeared steady and was still
        very easy to see. It just suddenly faded and was no longer visible.
        I did a very long integration just after it faded and found a faint
        object at the limit of my system. This appeared stellar and may be
        a geostationary satellite which I have still to check out.
        Since the range was around 29000 kilometres I dont think Mesenger
        went into shadow and the only explanation I can think off is that 
        the spacecraft changed orientation at around 20h30m54s UT thus 
        reducing its magnitude quite considerably.
    
    (4) Unknown #91038 bites the dust - well almost literally!. Mike
        has identified it as 86103D Cat.Number 17267. With the element
        data base I used at the time this satellite was nowhere near the
        area but a later element set shows that the satellite fitted the
        observation and running 22 seconds late. What makes 86103D
        interesting is that the perigee height was around 98 kms and
        apogee 11210 kms so this makes it the lowest perigee satellite
        I have ever tracked in my 48 years of tracking satellites.
        (Maybe the decay of OSO 7 may have beaten this but I was tracking
        this via radio so it doesnt count - another possibility is the
        decay of Echo 1 - I saw it visually a few orbits before it
        decayed.)  Unknown #91037 remains unknown.
    
    (5) Finally observed ISS/Shuttle as it passed nearly overhead at
        about 17.32 UT - got a nice "trailed" image of the very bright
        subject using a 30 second exposure. What was noticeable was how
        long it took the ISS/shuttle to fade from naked eye view after
        shadow entry - wonder if the cargo bay lights were on ??
    
    Cheers
    Greg
    
    
    
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