Getting my bearings.
The tilting of the wedge does not give me very much adjustment in azimuth (maybe ±2° if I am lucky) so I need to align the pillar with North-South as accuately as I can. My first idea was to use the shadow of a post at midday. You can see the pole which is 2.5 metres high placed where the pillar will go with strings to the fences to hold it upright. This did not work as well as I had hoped (quite apart from a long series of cloudy days). At this time of year the noon-day shadows are quite short and it did not reach the fence and I found extending it to the fence and then up it was more tricky than you might think. I then stretched a string across, just touching the pole, to locate a second datum point on the rear fence.
I wasn't happy that this had gone well and we got a few days of broken sunshine, so I set up my ETX125 and levelled it in alt-az configuration making sure that when the tube was level, it remained so as it turned 90°. At any given time I could line up the telescope with the Sun (in land mode so the motors were not running) and a planetarium program told me the azimuth bearing of the Sun at that time. I could then rotate the ETX by the requred angle (using its RA scale) to point it north, move it down in alt until I could look through it and see the fence. I found that I could look through the camera port with no eyepiece and see a reduced image but good enough to determine where to put a mark and a nail in the fence. I rotated the ETX 180° and determined where to mark the rear fence. I then stretched a string between the nails and checked that it passed along the length of the ETX. I repeated this three times and got slightly different positions each time, but one of them was within 1° of the line from the shadow.
Having got the telescope out there, I realised if the night was clear I could align it on the pole star which is always within 1° of due north, so even without correction the line would be near enough. However when I did this, polaris was only 42' away from due north and yet the line so determined was just over a degree away from the line derived from the Sun. I think the Polaris measurment is probably the more reliable but I checked it again after I had dug the hole and before I set up the form for the concrete.
The picture was taken later in the day, 12th July 2009