RE: RE: Space Track API - Problems

From: satrack@libero.it
Date: Wed Aug 29 2012 - 18:03:12 UTC

  • Next message: Marco Langbroek: "SATOBS ML (remote), 29 Aug 2012: Prowler"

    Hi Chip,
    
    yes, this query corresponds to that I coded in my program, 
    with the only difference that I request only the new files.
    
    However, at the first run the result is identical. 
    
    With this kind of solution I think we have to download much 
    more than 25.000 TLEs to obtain all the elements.
    
    Supposing the remote TLE table is named data_tle and that
    it works properly with a such big DB, we would need a query
    like this (maybe there is a more efficient one):
    
    SELECT * FROM data_tle, (SELECT NORAD_CAT_ID, max(EPOCH) as lastepoch from 
    data_tle group by NORAD_CAT_ID) as b where data_tle.EPOCH = b.lastepoch
    
    but I think it is not implemented right now. 
    
    Regards,
    Simone
    
    
    >----Messaggio originale----
    >Da: ciprian@sufitchi.com
    >Data: 28-ago-2012 23.20
    >A: <seesat-l@satobs.org>
    >Ogg: RE: Space Track API - Problems
    >
    >Simone,
    >
    >Did you try this query?
    >
    >https://beta.space-track.org/basicspacedata/query/class/tle/format/tle/order
    >by/FILE%20desc/limit/25000
    >
    >Chip
    >
    >-----Original Message-----
    >From: seesat-l-bounces+ciprian=sufitchi.com@satobs.org
    >[mailto:seesat-l-bounces+ciprian=sufitchi.com@satobs.org] On Behalf Of
    >satrack@libero.it
    >Sent: Monday, August 27, 2012 10:18 AM
    >To: seesat-l@satobs.org
    >Subject: Space Track API - Problems
    >
    >After a couple of days playing with the API, I found another
    >problem of the available functions (the first one is the 
    >missing 3 line format):
    >
    >If one wants to download the latest TLE for ALL the objects 
    >(bulk catalog), two ways can be used:
    >
    >1) request the latest elements for all the objects using such
    >a query:
    >
    >.../NORAD_CAT_ID/1--40000/sortby/EPOCH desc/sublimit/1
    >
    >unfurtunately this solution generates 40000 unions resulting
    >in a query that is too long to work properly. 
    >
    >Try yourself and you will see that this method works only for
    >a very limited range of NORAD_CAT_ID.
    >
    >I don't know if the situation will change later (after the test
    >phase), but I fear this will not work.
    >
    >2) request a larger number of TLEs (let say 20.000) 
    >starting from the new ones:
    >
    >.../FILE/>xxxxxx/oderby/FILE desc/sublimit/20000
    >
    >which is the solution abopted by my program.
    >
    >However also this solution doesn't work completely since:
    >
    >A) some elements are acquired only once in a few days 
    >and they are not in the first 20.000 objects so they are 
    >not downloaded!!!
    >
    >If you compare the bulk.txt file after the first download, more 
    >than 3000 Objects are missing!!!! (Most of them are DEB)
    >
    >B) if we want all the elements we have to generate a traffic 
    >much larger than actually required. (e.g. tents of MB against 
    >0.8 MB of the old zip bulk file).
    >
    >(this method works well only to keep the bulk file up-to-date,
    >e.g. once a day).
    >
    >If someone of you has got any idea on how to retrieve only 
    >the last TLEs of each object, I will be glad to implement is 
    >in the downloader.
    >
    >
    >Best regards,
    >Simone
    >
    >
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