Fw: [Molniya-l] Optical 14 May 2012

From: Greg Roberts (grr@telkomsa.net)
Date: Tue May 15 2012 - 13:38:36 UTC

  • Next message: Greg Roberts: "Correction 14 May 2012"

     Observations 14 MAY 2012
     ----------------------------
     
     Cosatrak 1 (Computerised satellite Tracking System).
     
     FLI ML8300M CCD camera with mechanical shutter + Trimble GPS
     
     Used with NIKON ED AF NIKKOR 80-200mm f/2.8 telephoto lens
     set at ~150mm focal length. Field of view 6.9 x 5.3 degrees,
     Time is accurate to within 50 milliseconds.
     
     Site 0433 : Longitude 18.51294 deg East, Latitude -33.94058 deg,
     Elevation 10 metres-situated in Pinelands (Cape Town),South Africa
     
     FOR CLASSIFIED.TLE:
     ----------------------
     05682 71 110E   0433 G 20120514172138880 55 15 2005570-735036 19
     05682 71 110E   0433 G 20120514172239691 55 15 1748570-720209 19
     05682 71 110E   0433 G 20120514172453121 55 15 1509240-481209 19
     10594 77 112F   0433 G 20120514163650081 55 15 0453480-371611 19
     10594 77 112F   0433 G 20120514163755933 55 15 0541440-284921 19
     10594 77 112F   0433 G 20120514163851789 55 15 0621400-185154 19
     10594 77 112F   0433 G 20120514164033154 55 15 0727570+031355 19
     14112 83 056A   0433 G 20120514171134827 55 15 0518100-095546 19
     14112 83 056A   0433 G 20120514171241631 55 15 0519080-170821 19
     14112 83 056A   0433 G 20120514171525510 55 15 0515120-375311 19
     14112 83 056A   0433 G 20120514171400391 55 15 0518470-263602 19
     14143 83 056A   0433 G 20120514165812874 55 15 0550560-013632 19
     14143 83 056A   0433 G 20120514170114818 55 15 0602410-245112 19
     14143 83 056A   0433 G 20120514170215445 55 15 0605380-341505 19
     14143 83 056A   0433 G 20120514170008056 55 15 0558320-152247 19
     14144 83 056D   0433 G 20120514164917209 55 15 0558510+085142 19
     14144 83 056D   0433 G 20120514165113953 55 15 0610010-032817 19
     14144 83 056D   0433 G 20120514165305270 55 15 0620410-182805 19
     21949 92 023A   0433 G 20120514175858866 55 15 0325540-670309 19
     21949 92 023A   0433 G 20120514180202306 55 15 0754205-255511 19
     21949 92 023A   0433 G 20120514180403106 55 15 0851409+152342 19
     22638 93 026A   0433 G 20120514163000727 55 15 0746450-270213 19
     22638 93 026A   0433 G 20120514163101591 55 15 0845190-003409 19
     22638 93 026A   0433 G 20120514163202725 55 15 0923070+183238 19
     28647 05 016B   0433 G 20120514173216398 55 15 1007560+411404 19
     28647 05 016B   0433 G 20120514173256998 55 15 1046410+355815 19
     28647 05 016B   0433 G 20120514173341578 55 15 1138570+271506 19
     13172 82 041C   0433 G 20120514175320396 55 15 1105177+420341 19
     13172 82 041C   0433 G 20120514175419854 55 15 1053518+335105 19
     13172 82 041C   0433 G 20120514175455635 55 15 1045100+264509 19
     
     STRAYS SEEN:
     -----------------------
     SL-14 R/B
     24731 97 006G   0433 G 20120514172239691 55 15 1740390-720704 19  +051 05
     METEOR 2-20
     20826 90 086A   0433 G 20120514172453121 55 15 1520090-435609 19  +045 05
     SL-14 R/B
     27061 01 058G   0433 G 20120514163755933 55 15 0537350-285642 19  +065 05
     DELTA 2 DEB (DPAF)
     27000 01 055D   0433 G 20120514175004783 55 15 1053110+392107 19  +065 05
     DELTA 1 R/B
     07946 75 052B   0433 G 20120514171134827 55 15 0520140-100015 19  +082 05
     THOR ABLESTAR R/B
     00447 62 060B   0433 G 20120514171241631 55 15 0524140-172629 19  +070 05
     ISS
     25544 98 067A   0433 G 20120514170114818 55 15 0602100-223838 19
     SL-16 R/B
     31793 07 029B   0433 G 20120514175204767 55 15 1055430+403557 19
     
     NOTES:
     -------
    (1) Good observing conditions. Set camera to -28 deg C.
     
     (2) Did a few leos then did a survey of the Clarke belt above about
        elevation 25 degrees in an attempt to find PAN. I now have 99
        images to go through (urgh )and have not yet decided whether I will
        merely do a quick check or measure everything which is the proper
        way to do it. Each image contains from at least 4 to around 20
        objects.
     
        Will have to do it manually as APEX does not seem to like the lens
        Im using. Solves some images but fails on most. (This is NOT the
        case with the 4 inch refractor or 6 inch reflector where normally
        it is at least 90% success.)
     
        Due to the relatively small aperture of the Nikon lens I am only
        getting down to about magnitude +12 and there is vignetting as
        well as field curvature due to the large field of view which also
        has fairly bad image quality on the one side of the field - camera
        not 100% parallel to the lens? - tolerance is about 0.005 inches.
        I suspect I am getting flexure in the camera/lens collimation as
        the elevation changes  and for some reason focus is not that good
        when facing west but is near perfect overhead and to the east.
        (seeing worse in the west because of Cape Town city and the
        mass of Table Mountain - heat source?)
     
        APEX most times seems unable to match enough stars- requires about
        30 - which it does by computing the trail length in pixels as well
        as the trail width and the position angle as these depend on
        declination, exposure length and seeing, to do a plate solution
        which would then correct for the lens problems.
     
        APEX typically finds about 1800-2000 stars in the field of view
        but ends up matching about 150 which are then subjected to the
        trail length test and this is where it fails as it usually
        matches only about 7 or 8. I tried using a deeper star catalog and
        get a quarter million stars in the field of view but the situation
        did not improve - no use trying to match a 15th magnitude star if
        the image only goes down to mag +12 !
     
        I am reluctant to lower the parameters set in APEX - eg set less
        matching stars etc as this will probably degrade accuracy so the
        solution is
     
        (a) measure manually - since only stars in the immediate vicinity
        of the satellites are used things like field curvature etc are not
        a critical factor
     
        (b) use a better quality lens. The NIKON lens is , according to
         reviews found on the Internet, a superb lens but then the
         reviewer did not test it on point sources so Im not going to
         waste money on another lens
     
        so manual its going to be whilst I use the current setup...
        I LIKE the wide field of view :-))))
     
        Cheers
        Greg
     
     
     
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