211206 corrected position for hf Mesh anchors

120621

19nov21 - measure location on T12 with bar.

On 17 19 nov21 measurements were done to decide where to locate the hf anchor blocks on T12 and T4. Unfortunately i screwed up
when doing the computation. We had measured that the anchors should be 40 inches below the tower step back. After recomputing things
(hopefully correctly) the bottom edge of the anchor should be 48.7 inches above the stepback.

On 06dec21 luis and i remeasured the distances to T8,T4,T12, and then T8 again using the tm50 theodolite.

We started by aligning the theodolite with the bottom center of the anchor on t8
We then swung in azimuth to point at the center of T4, and measured the point
Next we swung in azimuth to the center of T12 and measured the point.
We then continued swinging in azimuth back to the center of the anchor on T8 for the final measurement.

the table shows the measured values and pictures of where the measurements were taken (at the cross hair).

location	az Deg:D:M:S	za Deg,D:M:S	Distance ft	pictures
location	az Deg:D:M:S	za Deg,D:M:S	Distance ft	lowRes	hiRes
T8	.2226 deg 0d13'21.2"	53.6700 53d40'10.4"	867.89	.jpeg	.jpeg
T4	240.4391 deg 240d26'20.6"	53.6617 53d39'42.2"	849.00	.jpeg	.jpeg
T12	119.2421 deg 119d14'31.5"	53.6653 53d39'55.1"	855.35	.jpeg	.jpeg
T8	0.2290 deg 0d13'44.5"	53.6701 53d40'12.4"	867.94	jpeg	jpeg

Notes:

The za reference on T8 was the lower edge of the hook that is in place
1" in za is about .05 Inches at 850Ft.
1' in za is about 3 Inches.

What we did wrong previously

The theodolite was not placed at ao9 (the center of the 3 towers) because there is no longer any scaffolding that lets you get up
to where the theodolite is mounted.

Instead we placed the tripod about 8 feet away from the center of the 3 towers west toward T4. We assumed that spinning in azimuth at a fixed elevation was not going to make a large error if we were not at the center ... WRONG:)

Since the tm50 measures distance and angles we could have figured this out before....

tower	slope distance ft	elevation deg	vertical distance ft	t8-t12 vertical error
T8	867.89	36.3304	514.168	0ft
T12	855.35	36.3347	506.795	7.37 ft

The hf Anchor on T12 should be at the same vertical height as the anchor on T8.

The corrected measurement shows that the old measurement (swinging the theodolite in azimuth while not at the tower center) is 7.37 feet to low.
Using the bar, the old measurement placed the anchor 40" below the step back.

The correct position should be -40" + (7.37*12=88.44") = 48.4 inches above the stepback.

This number is hopefully correct. We should really put the scaffolding around AO9 and repeat the measurement from the center of the 3 towers.
One question i have is that the anchor on T8 looks to be below the old step back (which is no longer there). If all of the step backs are at the
same height then why is this new measurement saying the T12 anchor should be 48.4" above the step back?..(we'd better find some scaffolding for ao9!!).

Unfortunately this means that the anchor on T4 has been placed in the wrong position.

processing: x101/211206/hfmesh.pro

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