RE: Cosmos 1 Search

From: Ted Molczan (molczan@rogers.com)
Date: Fri Jun 24 2005 - 19:08:54 EDT

  • Next message: paul: "obs 25jun 05176 8305"

    Mark Whorton wrote:
    
    > Let me emphasize this -- if we are to learn that Cosmos 1 
    > actually is in orbit, you may very well be the ones to 
    > determine that and let us know.
    
    Since the object would be expected to be readily visible to the unaided eye, it
    would be fairly easy to conduct a planar search.
    
    Think of an orbit as an imaginary ring around the Earth. A lost satellite is
    moving rapidly along the ring, at an unknown location. If we can stare at the
    ring for as long as it takes the satellite to circle the Earth, then we must
    eventually see it. 
    
    Since the Earth rotates under the orbit, the imaginary ring appears to move
    across the sky, so we cannot just stare in one place and expect to see the
    object - we must frequently adjust our aim to follow the ring.
    
    Of course, for the method to work we need to have a pretty good idea of the
    location of the ring, i.e. the orientation of the orbital plane with respect to
    the Earth. 
    
    Radio signals that may have come from Cosmos 1 were received at several
    locations soon after launch, at about the expected times. For Cosmos 1 to have
    been the source, it would have to have entered at least very roughly the planned
    orbit. Therefore, it seems reasonable to use the planned orbit as the basis for
    a planar search.
    
    Appended are 18 element sets that differ from the planned orbit only in their
    mean anomaly. The mean anomaly is the angle that states a satellite's position
    within its orbit. Its range is from zero to 360 degrees. The appended elsets
    cover the mean anomaly at 20 deg intervals. Since the orbital period is 101 min,
    20 deg of travel within the orbit is equivalent to 101 / 360 * 20 = 5.6 minutes.
    
    So the time difference between passes predicted by successive elsets below is
    about 5.6 min, which is a reasonably fine net for searching.
    
    To plan a planar search, start by feeding all 18 elsets to your favourite
    prediction program. 
    
    Next, organize the output in chronological order from the earliest pass to the
    latest. This method works equally well for text and graphical programs. In the
    case of a graphical program, print the portion of the predicted track near
    culmination.
    
    In the case of a text program, I suggest summarizing the results by tabulating
    the circumstances of the culmination of each prediction. For example,
    
    Time   Azimuth   Elevation
    02:05    95         30
    02:11    97         34
    02:17    100        39
    etcetera
    
    This sample table means that if the satellite is in the planned orbital plane,
    and passes at time 02:05, then it will culminate in the east at azimuth 95 deg,
    elevation 30 deg. Since the Earth rotates toward the East, later passes will be
    higher in the east, and the very latest will be in the west.
    
    Since there was a problem during its ascent, it is likely that even if Cosmos 1
    reached orbit, it is somewhat different than planned; therefore, use the search
    plane only as a guide. If you see a reasonably bright satellite travelling in
    the expected direction, but quite a bit lower or higher in the sky than
    predicted, make note of it anyway.
    
    Since Cosmos 1 is expected to be bright (if its solar sail deployed), it is best
    to search with your unaided eyes, so that you can scan a wide area either side
    of the predicted path.
    
    Do not quit observing after spotting the first bright candidate to come along.
    Note the observational details, then resume your watch.
    
    Ideally, each observation you report will consist of one or more timed positions
    of a satellite with respect to the stars. For example, passed 2 deg below Vega
    at 02:12:15 UTC. Or passed between two stars, 30 percent from star A to B. If
    you happen to know the names of Star A and B, note them down; otherwise, sketch
    them along with other nearby known stars, sufficient to be able to identify them
    later.
    
    Note each object's approximate magnitude and whether or not the object was
    steady or varying in brightness. if varying, note its approximate period of
    variation.
    
    Upon completing your search, use Heavens-Above or CalSky to predict all bright
    satellites expected to pass during your search, to help identify the objects you
    saw. 
    
    Those that you cannot identify should be reported to SeeSat-L, since one of them
    might be Cosmos 1. More likely, they will prove to be objects normally too faint
    to be included in Heavens-Above's or CalSky's standard predictions, but which
    can be identified using other methods.
    
    Cosmos 1 was programmed to deploy its sail on 2005 Jun 26 during the period
    04:41:59 to 04:46:58 UTC, so it probably is not worth searching before then.
    
    If I have forgotten any important or useful observing tips, please correct me.
    
    Time permitting, I may cook up some additional search elsets, based on lower
    and/or more eccentric orbits than planned.
    
    Happy hunting!
    Ted Molczan
    
    
    1 70901U 70901A   05172.83732212  .00000000  00000-0  00000-0 0    00
    2 70901  80.0406 213.0716 0058440 136.4904   0.0000 14.25860033    18
    
    1 70902U 70902A   05172.83732213  .00000000  00000-0  00000-0 0    03
    2 70902  80.0406 213.0716 0058440 136.4904  20.0000 14.25860033    11
    
    1 70903U 70903A   05172.83732214  .00000000  00000-0  00000-0 0    06
    2 70903  80.0406 213.0716 0058440 136.4904  40.0000 14.25860033    14
    
    1 70904U 70904A   05172.83732215  .00000000  00000-0  00000-0 0    09
    2 70904  80.0406 213.0716 0058440 136.4904  60.0000 14.25860033    17
    
    1 70905U 70905A   05172.83732216  .00000000  00000-0  00000-0 0    02
    2 70905  80.0406 213.0716 0058440 136.4904  80.0000 14.25860033    10
    
    1 70906U 70906A   05172.83732217  .00000000  00000-0  00000-0 0    05
    2 70906  80.0406 213.0716 0058440 136.4904 100.0000 14.25860033    14
    
    1 70907U 70907A   05172.83732218  .00000000  00000-0  00000-0 0    08
    2 70907  80.0406 213.0716 0058440 136.4904 120.0000 14.25860033    17
    
    1 70908U 70908A   05172.83732219  .00000000  00000-0  00000-0 0    01
    2 70908  80.0406 213.0716 0058440 136.4904 140.0000 14.25860033    10
    
    1 70909U 70909A   05172.83732220  .00000000  00000-0  00000-0 0    05
    2 70909  80.0406 213.0716 0058440 136.4904 160.0000 14.25860033    13
    
    1 70910U 70910A   05172.83732221  .00000000  00000-0  00000-0 0    00
    2 70910  80.0406 213.0716 0058440 136.4904 180.0000 14.25860033    17
    
    1 70911U 70911A   05172.83732222  .00000000  00000-0  00000-0 0    03
    2 70911  80.0406 213.0716 0058440 136.4904 200.0000 14.25860033    11
    
    1 70912U 70912A   05172.83732223  .00000000  00000-0  00000-0 0    06
    2 70912  80.0406 213.0716 0058440 136.4904 220.0000 14.25860033    14
    
    1 70913U 70913A   05172.83732224  .00000000  00000-0  00000-0 0    09
    2 70913  80.0406 213.0716 0058440 136.4904 240.0000 14.25860033    17
    
    1 70914U 70914A   05172.83732225  .00000000  00000-0  00000-0 0    02
    2 70914  80.0406 213.0716 0058440 136.4904 260.0000 14.25860033    10
    
    1 70915U 70915A   05172.83732226  .00000000  00000-0  00000-0 0    05
    2 70915  80.0406 213.0716 0058440 136.4904 280.0000 14.25860033    13
    
    1 70916U 70916A   05172.83732227  .00000000  00000-0  00000-0 0    08
    2 70916  80.0406 213.0716 0058440 136.4904 300.0000 14.25860033    17
    
    1 70917U 70917A   05172.83732228  .00000000  00000-0  00000-0 0    01
    2 70917  80.0406 213.0716 0058440 136.4904 320.0000 14.25860033    10
    
    1 70918U 70918A   05172.83732229  .00000000  00000-0  00000-0 0    04
    2 70918  80.0406 213.0716 0058440 136.4904 340.0000 14.25860033    13
    
    
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