NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Data reduction request
From: Paul Hirose
Date: 2013 Nov 18, 16:44 -0800
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! --