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    Re: Data reduction request
    From: Paul Hirose
    Date: 2013 Nov 18, 16:44 -0800

    Richard Gaarden wrote:
    >
    > I recorded three solar altitudes today.  They are:
    > 66 41 53 Lower Limb {at} 15 13 37 GMT
    
    -0°03′14″ intercept (= observed - predicted)
    
    > 65 49 41 Lower Limb {at} 15 24 18 GMT
    
    -0°05′58″
    
    > 64 23 21 Lower Limb {at} 15 39 36 GMT
    
    +0°10′11″
    
    I assumed your "altitudes" are actually zenith distances (90 -
    altitude), since otherwise my values were grossly different from yours.
    I used sea level for your height and Nov 18 for date.
    
    > I used my old Wild T2 for the observations.  I would be grateful if someone 
    would reduce them to a Lat/Lon to help me verify what is or isn't working.  
    The AP is
    > -79 59 109 and 41 50 285 (best guess GPS).  BTW, they look, to me, to be 
    within about 1/2 mile..  But, I an a rookie prone to error!
    
    I won't even try to compute a fix from altitude observations so close in
    time.
    
    A few tips to make life easier for readers:
    
    1. Remember we have an international readership. If you simply say the
    date is "today" the actual date may not be immediately clear to people
    in distant time zones. The problem becomes worse if your message is quoted.
    
    2. In navigation, the usual format is latitude first. Software is
    usually designed so coordinates are entered in that order. I began to
    enter latitude -79 before realizing that was improbable (though not
    impossible). The chance of confusion is reduced if you use letters
    instead of signs, e.g., W instead of a - sign.
    
    3. Don't omit decimal points unless the abbreviation is obvious. In the
    case of your longitude, I'm guessing -79 59 109 means west 79 degrees
    59.109 minutes. But it might also mean -79 degrees 59 minutes 10.9
    seconds. In either case, a decimal point is missing.
    
    One poor practice is to use the decimal point as a separator between
    fields. E.g., 12.34.56 for 12 degrees 34 minutes 56 seconds. Or does it
    mean 12 degrees 34.56 minutes?
    
    One time I monitored police radio traffic as they hunted for a kidnap
    victim. The cell phone company was able to get coordinates, but they
    were in a strange format: latitude 34.567.890, for example. I think the
    second decimal point merely separated the decimal part into groups of
    three. Anyway, the cops couldn't make heads or tails of that.
    Fortunately, one of them found the kidnapper the old fashioned way -
    recognized his car as he drove around town talking to the victim's family!
    
    --
    I filter out messages with attachments or HTML.
    

       
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