X-37B OTV 3 elements

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Wed Dec 12 2012 - 16:29:41 UTC

  • Next message: ka8vit@ka8vit.com: "Re: FITSAT-1 LEDs"

    Greg Roberts has reduced a large number of points of OTV 3 and its Centaur, observed beginning about 19 min after MECO1,
    for a period of about 4 min:
    The first big revelation, at least to me, is that I had misinterpreted the sample of images from which I reduced what I
    believed were positions of the payload, which I took to be the trailing object in all of the images. I posted the
    results here:
    Waking up to Brad Young's negative-obs message this morning was not a good sign regarding the reliability of my results:
    Thank you, Brad and anyone else yet to be heard from, who gave up sleep trying to spot the object in the erroneous
    orbits I provided.
    Once I got into analyzing Greg's reductions all quickly became clear. It turns out that OTV 3 is the leading object.
    Without much difficulty I was able to fit a very reasonable looking, nearly circular orbit across the 4 min span:
    OTV 3                                                    345 X 363 km
    1 39025U 12071A   12346.78009259  .00006904  00000-0  50000-4 0    07
    2 39025  43.4966 137.4464 0013041 309.6975 307.5436 15.72393679    00
    Arc 20121211.78-1211.78 WRMS resid 0.014 totl 0.006 xtrk
    Barring any manoeuvres in the interim, I believe that this TLE should be accurate to well within 60 s time, 24 h after
    the epoch. It would be prudent to start observing perhaps 2 or 3 min earlier, taking care to allow for Earth's rotation,
    especially if observing with a narrow FOV at high elevation.
    My comment that all quickly became clear, applies only to the analytical results. I remain confused by the images, so I
    look forward to the opportunity to study the entire set, perhaps as video. I am beginning to suspect that in at least
    some of the images, the plumes that appeared to emanate from one object or the other, actually all belonged to the
    Centaur - the result of one or more burns, some of which may even have slightly preceded Greg's pass, and were now
    drifting in their own orbit. I further suspect that the Centaur was in the collision avoidance orbit, preliminary to its
    de-orbit burn, which may have occurred a few minutes after Greg's pass. I hope to work on the Centaur analysis this
    evening, and will report results ASAP.
    Finally, for the benefit of other analysts, in Greg's post of his reductions (first link in this message), his 99998 12
    845A is the payload, and his 99999 12 845B is the Centaur. He labelled them the other way around, perhaps led astray by
    my erroneous elements, based on my misinterpretation.
    Ted Molczan
    Seesat-l mailing list

    This archive was generated by hypermail 2b29 : Wed Dec 12 2012 - 16:30:21 UTC