TJM obs of 2007 May 18 UTC

From: Ted Molczan (molczanssl@rogers.com)
Date: Fri May 18 2007 - 01:29:47 EDT

  • Next message: Russell Eberst: "2007MAY18.OBS"

    This report consolidates all of my observations tonight.
    
    30772 07 006A   2701 G 20070518022939640 17 25 1651473+422115 77 S
    30774 07 006C   2701 G 20070518022940020 17 25 1651473+422115 77 S
    30772 07 006A   2701 G 20070518023023000 17 25 1733635+263752 18 S
    30772 07 006A   2701 G 20070518023100520 17 25 1752821+174998 37 E
    30772 07 006A   2701 G 20070518040513240 17 25 0912805+163845 57 S+075 05
    30774 07 006C   2701 G 20070518040513490 17 25 0912805+163845 57 S+090 05
    29651 06 057A   2701 G 20070518044545880 17 25 0259368+593859 87 S+070 05
    29651 06 057A   2701 G 20070518044557110 17 25 0233086+582952 57 S
    
    IOD format: http://www.satobs.org/position/IODformat.html
    
    Site 2701: 43.68764 N, 79.39243 W, 230 m
    
    Earlier, I reported my observations of Astro (07006A / 30772) in formation with
    Nextsat (07006C / 30774), on their first pass of the evening, at 02:30 UTC. I
    estimated their separation as 2.4 km, with an uncertainty of 50 percent:
    
    http://satobs.org/seesat/May-2007/0161.html
    
    I observed them on the second pass, at 04:05 UTC, at about 1225 km range. I
    spotted Astro first, about mag 7.5, and timed its passage relative a pair of mag
    8 stars, 0.10 deg apart. Soon, I spotted Nextsat trailing behind Astro, barely
    visible at about mag 9. They were a nice sight as they passed near Saturn.
    
    I estimated the angular separation of the spacecraft as about half that of the
    reference stars I had used in my observation of 07006A, or about 0.05 deg. Those
    stars had already passed from my FOV, so I am not all that confident in this
    estimate. The correct value probably is between 0.05 and 0.10 deg. At the range
    of 1225 km, that is equivalent to 1 to 2 km, roughly the same as on the previous
    pass, given the uncertainties.
    
    Note that the time of the above position of 07006C is estimated based on it
    trailing by 0.05 deg, at an angular velocity of 0.20 deg. I included it mainly
    to get the magnitude on the record.
    
    Later, at 04:45 UTC, I observed the NROL-21 payload, 06057A / 29651. It was 1.7
    s early relative my 9.9 day old elements:
    
    1 29651U 06057A   07128.29245851  .00021840  00000-0  13747-3 0    08
    2 29651  58.4997 217.2882 0009172  90.1254 270.0885 15.76094453    01
    
    My 2nd position of 06057A probably is the more accurate, because the reference
    stars were closer together and easier to see than those of the first position.
    
    Ted Molczan
    
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