Re: 5919 Obs #28385

From: Björn Gimle via Seesat-l <seesat-l_at_satobs.org>
Date: Sun, 11 Sep 2016 20:43:24 +0200
I noticed that the inttles "+MA" elset predicts tonight's pass for me
(19:51 UT) 4.7 minutes earlier than my suggested "7 AOP".
Also that "+MA" has 50% higher drag than the original old TLE, which I
began to suspect.
This probably means that it has completed seven more orbits than that elset
predicted, ie almost a full day in error after 163 days.

But the "+MA" still predicts a pass (at 42 deg alt in the SE for me) 2
degrees higher than "7 AOP", like yesterday.

So I recommend "+MA" until new obs arrive. I may still have clear skies !

/Björn

-----------------------------------------

2016-09-11 18:58 GMT+02:00 Björn Gimle <bjorn.gimle_at_gmail.com>:

> Last night I found USA 179 r after a partial track scan. It was only 16
> min early on the classfd 163 days old, yet after adjusting B* to fix the
> time offset, it still predicted it 4 degrees above the obs at 42 deg alt in
> the SSE.
> With inttles the figures were 13 min and 3 degrees.
> Actually, the drag effect could make for several orbits in error-
> increasing from 0.1 orbit to 1.1 orbit requires only a 7% drag increase.
> I also changed AOP+MA to get the track closer to my obs, it might be more
> helpful for a few days.
> But this TLE shows a discrepancy in the track angle.
>
> I'm at a loss as to which elements to adjust - more obs are needed.
>
> USA 179 r +7 AOP
> 1 28385U 04034B   16091.25392007 0.00052500  00000-0  10019-2 0    00
> 2 28385  57.3390 119.7392 3808439 262.3433 232.2776  7.88880991    03
> USA 179 Rk +MA
> 1 28385U 04034B   16254.46759977 0.00083586  00000-0  15065-2 0    00
> 2 28385  57.3489 276.6181 3697518 341.0707  33.7470  8.10254303  1633
>
> IOD:
> 28385 04 034B   5919 G 20160910201034500 18 25 2210700+140900 55 R
> 28385 04 034B   5919 G 20160910201054500 18 25 2219900+160600 55 R
>
> --------------------------------------------------------
> Björn Gimle, COSPAR 5919
> 59.2617 N, 18.6169 E, 51 m
> Satellite observation formats described:
> http://www.satobs.org/position/IODformat.html
> ---------------------------------------------------------
>
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Received on Sun Sep 11 2016 - 13:44:04 UTC

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