[IGSMAIL-6031]: Re: GLONASS Broadcast Ephemerides (GLSV, KHAR)

[Lytvyn Mykhailo]

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IGS Electronic Mail      01 Dec 02:23:01 PST 2009      Message Number 6031
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Author: Mykhailo Lytvyn


Dear colleagues,

by this letter I should like to say that I am grateful to Tim Springer 
for pointing NovaRS bug out. I hope we shall fix this annoying mistake 
in GLONASS NAV files at the beginning of the next week.


Tim.Springer at esa.int NAPISAW(LA):
> As some of you may have noticed the broadcast orbits in the IGS GLONASS 
> combination always look very bad for the Monday of each week. In doing 
> some "reprocessing" for the upcoming AGU meeting I have run into a similar 
> problem with our software as  well with "crashing" Monday solutions. 
> Whilst digging into this problem I found out that in the reprocessing I 
> forgot to disable the usage of the combined "brdc" file which we normally 
> ignore in our IGS routine operations since it gave some problems in the 
> past and still does today. So I have taken some time to look into where 
> the problem comes from. It seems that the root cause is that almost every 
> Monday, probably due to the week "switch over", the GLONASS broadcast 
> ephemerides from the stations GLSV and KHAR are producing erroneous 
> epochs. This can easily be seen in the files as they report the epoch as, 
> e.g., 44 min and 59.0 sec but all other stations give the same information 
> for the 45 min and 00.0 sec epoch. Since the merged "brdc" file just adds 
> these different epochs to the merged file also the combined "brdc" file 
> contains this error. 
> 
> So to resolve this issues I propose the following corrective actions:
> Station managers from GLSV and KHAR are to correct their software for the 
> generation of broadcast ephemerides
> 
> GLSV and KHAR are the only two sites listing the NovaRS software in their 
> broadcast navigation files. So most likely the NovaRS software is causing 
> the issue at hand.
> 

-- 

With best regards,
		    Mykhailo

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Mykhailo Lytvyn
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Junior Research Scientist
Department of Space Geodynamics,
Main Astronomical Observatory of the
National Academy of Sciences of Ukraine,
27, Ac. Zabolotny Str., 03680, Kiev, UKRAINE
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Phone  : +380 (44) 526-4759
Email: misha at mao.kiev.ua
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