Re: [find_orb] DE Files

Bill Gray Jun 23, 2013

Hi Tony,

The BSP files are "binary SPICE kernel files", not plain old
JPL ephemeris files. Find_Orb requires the latter; it doesn't know
anything about SPICE. The file you want (for DE-422, at least) would be

ftp://ssd.jpl.nasa.gov/pub/eph/planets/Linux/de422/lnxm3000p3000.422

Save that file to the Find_Orb folder, and it will be found automatically.

This file is about 544 MBytes, and provides coverage from years -3000 to
+3000. You can get years 1970 to 2020 (plenty for many uses) in a mere 4.7
MBytes at

http://adams.dm.unipi.it/~orbmaint/orbfit/JPLEPH/DE405.dat

Again, download it and put it in your Find_Orb folder, and it'll be
automatically detected.

I see that there are some JPL ephemeris files that really should be detected
that aren't. If you download

http://www.projectpluto.com/jpl_eph.txt

to your Find_Orb folder, then you can get some intermediate-sized
ephemerides such as this one, covering 1900 to 2053 in 13 MBytes :

ftp://ssd.jpl.nasa.gov/pub/eph/planets/Linux/de421/lnxp1900p2053.421

55 MBytes can get you 1600 to 2200 :

ftp://ssd.jpl.nasa.gov/pub/eph/planets/Linux/de405/lnxp1600p2200.405

The most recent version of DE released thus far is DE-430, which includes
343 asteroid perturbers. However, the difference for actual orbit determination
between DE-405 and the more current ephems is almost completely unnoticeable.

-- Bill

On 06/23/2013 06:00 PM, aje160744 wrote:
> I have file DE422.bsp file obtained from here:
>
> ftp://ssd.jpl.nasa.gov/pub/eph/planets/bsp.
>
> Now I've got it what do I do with it? I put it in the Find_Orb directory but the program does not seem to recognise it.
>
> Thanks for any help.
>
>
>
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