CORRECTION: Crew Dragon initial elset estimates

From: Marco Langbroek via Seesat-l <seesat-l_at_satobs.org>
Date: Sun, 24 May 2020 13:48:38 +0200
CORRECTION to my previous post with slightly altered elsets !!!!!

My post 15 minutes ago was inadvertently with elsets for launch at 20:33:00 UT,
while the launch time now quoted lists 20:33:33 UT.

So report of the previous post here, with new elsets, and ignore the previous
post!  (if an admin can remove the previous one from the archive, that would be
cool)

********** revised repost below *********

Only 3 days to go before the launch of the Crew Dragon.

Weather permitting, launch will be at 27 May 2020 20:33:33 UT from platform 39A.

I posted an estimated elset on this list earlier, but give a revision here,
partly because of a small 1-minute shift in launch time (my initial elset was
based on 20:32 UT).

The following elset estimate is based on the Crew Dragon Demo-1 flight initial
insertion orbit:


CREW DRAGON
1 70000U 20999A   20148.85443285 -.00003603  11390-4  00000+0 0    03
2 70000  51.6423 089.9835 0122953  45.6251 315.4951 15.99554646    09


And this elset is based on a 'regular' cargo Dragon flight insertion orbit:


CREW DRAGON*
1 70001U 20999A   20148.97943026 -.18507952  12289+0 -23808-1 0    07
2 70001  51.6233 089.2887 0096856  46.3995 314.2887 15.95177824    04


I should add that I am not entirely sure the initial elset published for Crew
Dragon Demo-1 is okay - the epoch of that elset is odd, as it predates launch,
and it was reissued 3 times.

If I take the next published orbit instead, I get this:


CREW DRAGON**
1 70002U 20999A   20148.87341560 -.00003589  11345-4  00000+0 0    03
2 70002  51.6437 089.7781 0114760  48.6187  62.8495 15.97921108    07


...but that is based on an orbit epoch for the 2nd revolution, i.e. after orbit
adjustments during the first revolution.

For the first revolution pass over Europe, all three elsets give times and
tracks that are close - some 12 seconds difference in pass time between elset
7000 and 7002 for example.

I suggest you use elset 7000, but be aware of some possible time (up to a minute
or so) and cross-track error (up to a degree or so).

- Marco


-----
Dr Marco Langbroek  -  SatTrackCam Leiden, the Netherlands.
e-mail: sattrackcam_at_langbroek.org

Station (b)log: http://sattrackcam.blogspot.com
Twitter: _at_Marco_Langbroek
-----
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Received on Sun May 24 2020 - 06:49:21 UTC

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