NavList:

When I set up the Multiyear Interactive Computer Almanac on my computer the elevation of the viewing site was included.

As to my notions of North, it has been an ongoing project for some time. Using Google Maps I located a series of fence posts on my property which span something like 100 yards. Repeated "picks" yielded average values of Lat/Lon. I then moved, on the photo, to the other end of the field and selected another post approximately orthogonal to the first line of posts and located it in the same manner as the first post. Last, I picked a spot on the orthogonal fence line with the same Longitude as my original post pick and calculated the distance down the fence line to the second reference post. Within the accuracy of the system and my "picks" the original post and the calculated spot were on the same meridian. Obviously not "traditional navigation." I refined this "personal" North in variety of ways (one described on this list). When I gained the ability to use the theodolite at higher angles, I turned to sun sights.

Subsequent to my unsatisfactory sun sights, I have made observations of Polaris on three occasions. My crude attempts to establish North were good enough that Polaris was in the field of view (1.6 degrees) on my first attempt. This took place when the sky was bright enough that I could not locate the star either by naked eye or with binoculars. As, I am sure you know, in the vicinity of elongation the star, unlike the sun, has slow tangential apparent motion. I found it rather simple to establish North to less than 30 seconds.

The "proof" of the accuracy is that on subsequent sightings I have set up the theodolite, oriented the horizontal scale by back sighting my established personal North reference point, preset the instrument for a future time and when the preset time arrives the star is easily within less than 30" of the cross hairs.

After allowing for refraction, my vertical accuracy is significantly better than horizontal accuracy. I find this curious but have not explored the matter.

I have built a pillar for the theodolite and that has reduced the magnitude of some variables. 1/16 inch variation in the location of the theodolite or the back sighting point on my 100 yard baseline can introduce about 4" of variation. Now, I need to refine my North sighting point to allow for more repeatable orientations.

With "North" nearly in hand, I want to log some stellar transit times to personally establish the length of the sidereal day. More foolishness, I suppose, but I enjoy that sort of thing.

When I rather casually began looking for North, I had no notion of how demanding, for me, this would become.

Once again, my thanks to all who have offered advise or direction.

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