Updated elements

From: Ted Molczan (ssl3molcz@rogers.com)
Date: Sat Jul 14 2012 - 14:21:18 UTC

  • Next message: Kevin Fetter: "Tecsar obs"

    The following TLEs are based on observations by Kevin Fetter, Alberto Rango, Scott Tilley and Brad Young, during 2012
    Jul 11-14 UTC.
    
    Elisa E24                                                673 X 688 km
    1 38008U 11076B   12196.19622887  .00000257  00000-0  50000-4 0    02
    2 38008  98.1589 272.4606 0010692 121.7407 238.4838 14.63068126    01
    Arc 20120711.13-0714.2 WRMS resid 0.030 totl 0.014 xtrk
    
    Elisa E12                                                679 X 681 km
    1 38010U 11076D   12196.19638590  .00000256  00000-0  50000-4 0    02
    2 38010  98.1819 272.4855 0001493 112.0474 248.0886 14.63069469    03
    Arc 20120711.88-0714.2 WRMS resid 0.064 totl 0.033 xtrk
    
    My Elisa designations are somewhat arbitrary. I have been taking D to be the one with the higher RAAN, but the latest
    analysis suggests that is a poor criterion. What matter for now, is that we can distinguish between them.
    
    Below is the updated list of observations. Please note that in yesterday's compilation, under 11076B, I listed the wrong
    observations by Scott Tilley for Jul 12. The following are correct.
    
    38008 11 076B   1775 G 20120711030156431 15 25 1836711+044062 37 S
    38008 11 076B   1775 G 20120711030211646 15 25 1835681+110650 37 S
    38008 11 076B   1775 G 20120711030223258 15 25 1834490+162168 37 S
    38008 11 076B   1775 G 20120711030237305 15 25 1833356+233268 37 S
    38008 11 076B   8049 G 20120711062112966 15 25 1653692+390197 37 S
    38008 11 076B   8049 G 20120712065932068 15 25 1228091+400169 37 S
    38008 11 076B   8049 G 20120712065935471 15 25 1222317+403083 37 S
    38008 11 076B   8049 G 20120713055703599 15 25 1939321+291551 37 S
    38008 11 076B   8049 G 20120713055706568 15 25 1942485+300651 37 S
    38008 11 076B   1775 G 20120714031525076 15 25 1733402+120245 37 S
    38008 11 076B   8336 G 20120714045341790 17 25 1350247+601204 48 S
    
    38010 11 076D   4542 G 20120711210732710 17 24 2238050+811483 28
    38010 11 076D   4542 G 20120711210746950 17 24 0054480+824995 57
    38010 11 076D   8049 G 20120712065943879 15 25 1230249+393980 37 S
    38010 11 076D   8049 G 20120712065943879 15 25 1222559+402034 37 S
    38010 11 076D   8049 G 20120713055716578 15 25 1937983+291333 37 S
    38010 11 076D   8049 G 20120713055719448 15 25 1939187+303783 37 S
    38010 11 076D   4542 F 20120713204217140 17 24 2127830+315000 28 S
    38010 11 076D   4542 F 20120713204305420 17 24 2222171+483408 37 S
    38010 11 076D   1775 G 20120714031538589 15 25 1732107+120616 37 S
    38010 11 076D   8336 G 20120714045356340 17 25 1346356+601786 38 S
    
    The next step will be to locate the two remaining Elisa satellites, which probably operate in a similar formation
    somewhere else in or near the plane of 11076B and D. A retrospective of the operational orbits of the earlier Essaim
    satellites may offer a clue.
    
    They appeared to fly in formation, with pairs of satellites in two planes separated by several degrees. Within a plane,
    leader and trailer were separated by several hundred kilometres, and the leaders of both planes crossed the equator at
    about the same time. At mid-latitudes, this  arrangement resulted in a roughly rectangular formation, several hundred
    kilometres on a side.
    
    Based on the above elements, the separation between Elias E24 and Elisa E12 currently varies between 101 km and 127 km
    on each revolution. That suggests a tighter formation than that of Essaim, which may mean a closer planar separation
    between the pairs.
    
    It is also possible that the square formation has been abandoned in favour of coplanar pairs, separated by some
    distance.
    
    A planar search should turn them up.
    
    Ted Molczan
    
    
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