corrected real SEDSAT two line elements

Philip Chien (kc4yer@amsat.org)
Sun, 25 Oct 1998 11:07:51 -0500

At 7:32 PM -0400 10/24/98, Philip Chien wrote:
>The launch was the 61st of the 1998 calendar year, hence Deep Space 1 is
>1998 61A.  Based on the two element sets I received Sedsat is the *C*
>object since it was deployed in the forward direction.
>
>Deep Space 1 Rocket Body (Delta 2nd stage)
>1 25509U 98061B   98297.62368702  .00000531  00000-0  10000-3 0    22
>2 25509  31.4542  34.5533 0364397 250.7872 105.2982 14.23437438    15
>Sedsat (SO-33)
>1 25510U 98061C   98297.62362948  .00000565  00000-0  10000-3 0    16
>2 25510  31.4549  34.5507 0374007 250.8775 105.0980 14.24557218    13

I am somewhat confused by the identified element sets which USSPACEOM is
now distributing -

DELTA 2 R/B(1)
1 25510U 98061C   98297.83386602  .00000564  00000-0  10000-3 0    22
2 25510  31.4472  33.3731 0373776 252.5693 103.3706 14.24490847    48
SEDSAT-1
1 25509U 98061B   98297.76392310  .00000546  00000-0  10000-3 0    36
2 25509  31.4430  33.7710 0370167 252.0548 104.0418 14.23717857    35

These elements identify object 25509 (1998 61B) as Sedsat, not 25510 as I
previously determined based on the elements.

It's not likely that USSPACECOM's radars could not differentiate between
the fairly large Delta 2nd stage and the very tiny Sedsat so I have to
conclude that these elements and object numbers are correct.

The difference in drag between the two objects is significant so they'll
move apart gradually over the next several days with the upper stage
'pulling ahead'.

I'm at a loss as to why the Delta 2nd stage was ahead of Sedsat in the
initial element set.  It's possible that there was a minor glitch in the
determination of the actual orbits, and possible - although highly unlikely
- that the objects were initially misidentified and mixed up.

In any case these latest elements come from "the source" and should be used
to track Sedsat - or to try to view the upper stage.


Philip Chien, KC4YER
Earth News
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all-around nice guy, etc.