RE: about observations

From: Ted Molczan (seesat@rogers.com)
Date: Sun Sep 18 2005 - 11:35:24 EDT

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    K. Martins asked:
    
    > 1) I have couple of objects which do not fit with 
    > heavens-above data and cal sky data. How can I identify these 
    > objects?
    
    There are two general methods.
    
    1. Non-graphical
    
    If your observation can be reduced to a reasonably precise position and time,
    say 1 deg position and 10 s time, or better), then I recommend using one of the
    non-graphical programs: either Mike McCants' findsat or my IDSat:
    
    http://users2.ev1.net/~mmccants/programs/findsat.zip
    
    http://users2.ev1.net/~mmccants/programs/IDSat.zip
    
    These programs process a file of TLEs (provided by the user) and list all that
    passed within a specified angular distance and time relative the observed
    position and time.
    
    
    > I want write this data in IOD format but I do  not 
    > know my station id. Where can I get info about my station id?
    
    The number of available Station ID numbers is limited, so they are assigned only
    to observers who demonstrate that they are likely to contribute precise
    positional or magnitude observations on a fairly regular basis. For new
    observers, this means that they will not have an ID number at first, in which
    case, they should simply enter zero for station ID when reporting in any of the
    formats that require an ID. Of course, the site coordinates should be included
    in each observation report, regardless of having an ID number.
    
    Note that neither findsat nor IDSat require the use of IOD or the other formal
    reporting formats; however, IDSat provides the option to use them.
    
    
    2. Graphical
    
    If your observation cannot be reduced to a reasonably precise position and time,
    then a graphical method is best. Since you have already this with CalSky and
    Heavens-Above, without success, I recommend the use of a PC-based graphical
    program. A popular one is Rob Matson's SkyMap:
    
    http://users2.ev1.net/~mmccants/skymap66/index.html
    
    I do not use SkyMap; however, I know that other observers - Bjorn Gimle comes to
    mind - have used it successfully to plot all satellites that passed near the
    approximate position and time of an unidentified satellite. Like the
    non-graphical methods, Skymap requires that the user provide a file of TLEs.
    Space Track issues such files twice daily, which contain all unclassified
    objects:
    
    http://www.space-track.org/perl/login.pl
    
    The data is free, but you must wait for your subscription to be approved. You
    should be mindful of the site's restrictions on the sharing of data.
    
    
    > My location Riga lat:57 lon:23=20
    
    Fairly precise site coordinates are required to maximize the probability of
    making a confident identification. Positional observers generally determine
    their lat and long to 0.0001 deg, and altitude to within a few metres. For
    casual (i.e. not very precise) observations, 0.01 deg accuracy in lat and long
    is sufficient, and you need not worry about altitude unless you live on a
    mountain.
    
    
    > 2) Is there some software which transforms IOD data to TLE 
    > data and can I obtain this soft too?
    
    I do not recall any published orbit determination software that directly reads
    IOD or the other formal reporting formats. Here are a couple of differential
    correction programs used to update known orbits using new observations:
    
    http://users2.ev1.net/~mmccants/programs/fitelem.zip
    
    http://users2.ev1.net/~mmccants/programs/elcor.zip
    
    
    > 3) I have observed satelite which fits good with the solrad 
    > 7b (usspacecom: 1291), but there is doubt because of 
    > magnitude. May be its magnitude is grater than predicted. 
    > Have someone observed this satelite too?
    
    In order to respond to this question, it is necessary to have the details of
    your observation.
    
    Ted Molczan
    
    
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