Re: Simultaneous ISS/Venus Transit

From: Thomas Fly (tfly@alumni.caltech.edu)
Date: Wed Jun 09 2004 - 13:36:44 EDT

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    Hi John & Arnold,
    
    Here's the one I'm waiting for- finally for a chance to bag my first transit
    video with my (relatively) new Unibrain Fire-i webcam!
    http://iss-transit.sourceforge.net/firewire-webcam.html
    
    The 5 month-old Dell mini-tower shown on that page is what I'm now using to
    generate my transit reports (it runs at 2.8 GHz, actually).  Since I still
    continue to fiddle with the program code, I run WorldView (in "search mode," for
    report generation) from within my Borland JBuilder X (i.e., version 10)
    development environment, which recommends 768 MB of RAM!  Since the Dell came
    with "only" 512 MB, I just ordered another 512 MB for it.
    
    Hopefully, that'll speed things up (a lot), since at present the 2.8 GHz Pentium
    4 gets thru the reports in only about 2/3 the time (~72 minutes) as my 3
    year-old 1 GHz / 512 MB Pentium 3 w/JBuilder 8.  I hope switching (soon) to
    GTOPO30 will speed things up even more, since currently I have to adjust
    predictions according to each subscriber's stated elevation above sea-level.
    
    I did get GTOPO30 implemented for the ISS/Venus transit tracks, but there's a
    little more to do to incorporate it into the subscriber reports:
    
    
    These results are based upon a TLE posted Monday, June 7 by NASA's Mission
    Control Center
    
    1 25544U 98067A   04159.51929753  .00020000  00000-0  20000-3 0  9009
    2 25544  51.6330  15.0298 0005537 207.1571 152.9300 15.68796178 36803
    
    A - time on June 8 (Universal Coordinated Time / UTC)
    
    B - elevation angle of Venus and the ISS at the transit time
    C - azimuth angle of Venus ( + is East from North; - is W from N)
    D - distance to the ISS (km; km / 1.609 = mi)
    
    E - latitude for observing the transit
    F - longitude
    G - elevation above sea-level (meters)
    
    A-------  B--- C----- D---  E------- F--------  G---
     5:30:12  60.7  116.1  419   39.4951   69.0556  4012 > highest; Tajikistan
    
     5:31:23  62.4  128.0  414   42.4489   73.9579  3867 > highest near Contact 2;
    Kyrgyzstan
    
     6:58:08  51.1   88.6  464   28.8024   32.4188  1322
     6:58:09  51.1   88.7  464   28.8526   32.4684  1033
     6:58:10  51.2   88.8  464   28.9027   32.5168   577
     6:58:11  51.2   88.8  463   28.9529   32.5664   275
     6:58:12  51.3   88.9  463   29.0030   32.6166    32
     6:58:13  51.3   89.0  463   29.0531   32.6686   H2O
     6:58:14  51.4   89.1  462   29.1032   32.7209   H2O
     6:58:15  51.4   89.2  462   29.1533   32.7732   H2O > Red Sea
     6:58:16  51.5   89.3  462   29.2034   32.8256   H2O
     6:58:17  51.5   89.4  462   29.2534   32.8780   H2O
     6:58:18  51.6   89.5  461   29.3034   32.9313    95
     6:58:19  51.6   89.6  461   29.3534   32.9855   298
     6:58:20  51.7   89.6  461   29.4034   33.0390   420
     6:58:21  51.7   89.7  460   29.4533   33.0901   241
     6:58:22  51.8   89.8  460   29.5032   33.1476   829
    
     6:59:00  53.6   93.5  450   31.3810   35.1810   576
     6:59:01  53.6   93.6  450   31.4300   35.2346   465
     6:59:02  53.7   93.7  450   31.4789   35.2885   365
     6:59:03  53.7   93.8  450   31.5278   35.3434   399
     6:59:04  53.8   93.9  449   31.5769   35.3925  -321
     6:59:05  53.8   94.0  449   31.6258   35.4466  -405
     6:59:06  53.9   94.1  449   31.6746   35.5014  -405 > lowest; The Dead Sea
     6:59:07  53.9   94.2  449   31.7233   35.5562  -405
     6:59:08  54.0   94.3  448   31.7720   35.6118  -318
     6:59:09  54.0   94.4  448   31.8207   35.6678  -181
     6:59:10  54.1   94.5  448   31.8691   35.7259   219
     6:59:11  54.1   94.6  448   31.9175   35.7843   669
     6:59:12  54.1   94.7  447   31.9660   35.8417   964
     6:59:13  54.2   94.8  447   32.0145   35.8975  1051
    
    I'm not yet sure if those numbers really represent elevations above sea-level
    (there's a good bit of the GTOPO30 documentation that I haven't read), but they
    are in close agreement with the values I've checked at selected locations using
    CalSKY.
    
    I'm really treating them as heights above the WGS72 ellipsoid, so another TODO
    is to switch to WGS84 constants; but first I have to determine if there are any
    non-obvious interactions in doing so, with SGP4 for example, and what may be
    required to steer around any such interactions.
    
    The weather here has been dreadful lately, with thunderstorms predicted
    virtually every day, that nonetheless hardly ever leave a drop of much-needed
    rain!  So, I'm not exactly planning my day around transit observing, the
    afternoon of June 17....
    
    
    I haven't heard a thing about anybody catching a simultaneous ISS / Venus
    transit- very discouraging, after all the work and advance promotion.  I was
    really hoping Michael Gill would get it, during his trip to Greece, but I've yet
    to hear from him.
    
    Tom
    
    
    Need to change my report back to miles...
    
    A - travel distance (kilometers) and direction
    B - date
    C - time
    D - elevation angle of the ISS
    E - azimuth angle of the ISS ( + is East from North; - is W from N)
    F - range (kilometers)
    G - latitude for observing the transit
    H - longitude
    I - how far (kilometers) can I be from the centerline?
    
    For other than solar transits:
    J - lunar transits: is space station sunlit?
        planetary encounters: 1=Mercury; 2=Venus; 4=Mars; 5=Jupiter; 6=Saturn
    K - sun elevation angle
    L - sun/moon or sun/planet separation angle
    
    A------- B----- C-----  D--- E----- F--- G------- H-------- I---- J K---- L----
     10.9 W  17 Jun 150906  65.4 -110.7  399  34.8855  -81.9989   1.9
      9.7 SW            06.68                 34.8537  -81.9590   1.9
     10.0 SW 17 Jun 150907  65.4 -110.6  399  34.8390  -81.9405   1.9
    
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