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george huxtable  writes:

> There remains something of a mystery about Asbjorn's big discrepancy, in
> what should be a very accurate observation. Perhaps he will repeat his
> measurement, next time the Sun shines in Trondheim, and before it gets too
> low to observe well from his Northerly latitude.

I am very sorry for being silent so long, it is partly due to email
server problems.  I hope I have not lost any emails.

When it comes to the GPS position, I am quite certain it is correct.
It is what is reported by my hand held GPS receiver, and I bring it
with me every new place I try the sextant.  It is set to WGS-84.

I have taken a few more measurements.  I don't have the exact numbers
here right now, but the summary is:

 - About six sights with red/blue plastic on artificial horizon.
   These are quite good, being about +/- 1.5' from calculated values.
   I am a beginner, so getting errors is expected as long as the mean
   over several sights is about right.

 - Three more sights with clear glass on artificial horizon.
   This time I get a mean that is about 2' off from calculated.

And when I look through my earlier measurements, all sights from the
same "batch" (i.e those taken at about the same time and same set-up)
gives about the same error in offset.  E.g when I have an error of 5'
in a sight, all sights taken at that time have about the same error.
I have not yet understood why, and I have too little statistical
material to give any conclusions about this.  It might be coincidence.

I got a tip here on NAV-L that I perhaps use the wrong reflection.
Could I see the reflection on the bottom of the horizon instead of the
surface?  I don't think so as I would expect the error to be much
larger then.

When I relize what kind of mistake I do, or what is the cause of this,
I'll be sure to report it here.

Asbjørn

   

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