FIA 2 (NROL-25): Evolution of Optical Appearance

From: Scott Tilley (
Date: Fri Apr 06 2012 - 22:14:05 UTC

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    Hi All
    After obtaining my third visual obs of FIA Radar 2, 2012-014A, 38109 
    last night, I was struck by the dramatic change in optical appearance of 
    the s/c from my obs of it during the 4th orbit on April 4th. 
    Particularly after looking at the video footage of the two passes side 
    by side...
    I choose last night's pass so that it would coincide with almost the 
    same geometry as the pass I observed during its 4th orbit.
    What struck me was that on the 4th orbit the s/c was rather dim and last 
    evening rather bright and not as affected by phase angle as earlier.
    See for yourself in this video (43MB):
    Please note that the polar mount I use was inverted during the second 
    obs session relative to the first obs session.  To help you understand 
    the mount geometry and how similar the passes where, here are two 
    Heavensat screen grabs showing the relative geometry of the beginning of 
    each video segment.
    Here's what the mount/lens and camera looks like in daylight:
    I propose that this shows that the radar antenna was deployed sometime 
    between these two observations.  It will be interesting to conduct a 
    review of other observations during this period to perhaps nail down 
    when they actually deployed the antenna array and how much this affected 
    the s/c's brightness and other optical characteristics...
    Looking forward to other ideas...
    Scott Tilley
    8049 ST 49.4348 -123.6685 40. Scott Tilley
    8048 ST 49.4175 -123.6420 1. Scott Tilley
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