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Torbhlaran

#24 Torbhlaran Thom A2/15,  Ruggles: AR25 NR8639 9449

Note: All sites with horizons nearer than 1 km. (as here) must be treated with caution. Having said that these results are offered for the record

A 'playing card' slab about 2.0m.x 1.0m.x 0.2m., situated in an approx 700m wide valley. The SW face is very flat and has cupmarks on it. The upper part of the SW face is oriented about 130-131° /310-311°.

There is a clear hill feature to the SE, but there is no alignment.  Epoch 9 and 10 refer to Thom's solar intermediate declinations and are approx. -8°.5 and -16°.5

To the NW there is a steep wooded hillside with a grassy/rocky ridge.  This looked unpromising.  However, close examination showed a rock outcrop behind the tree on the ridge.

Behind the tree there is a rock outcrop with a small but distinct block as part of it.  To the left and right the nearby skyline is featureless and mainly grassy.  The suspected foresight could only just be seen in the x30 theodolite view, and then only in March/April before growth of leaves.

The following was found:-

Note:- This apparent foresight is relatively close and at a significant elevation which is reminiscent of #12 Sluggan and #18 Glennan.   So for the same reasons instead of the 'normal' observing position of 2m. back, observations were made over the top of the stone. This was 3.0m. back from the nearest point of the stone.

A white marker was used at the suspected foresight. This aided identification, but difficulties remained.  Therefore a template of the foresight was cut to size and positioned in a visible position a known distance to the side ( 3.28m.) at the same level as and at right angles to the observing direction.

Then by observing the cutout from an exactly equivalent position relative to the stone (i.e. 3.0m. back and 3.28m to the right) a meaningful declination should be obtained.

Two independent sets of observations were made on different days.  The declination values found were 28° 55'.8 and 28° 56'.3.   These agree closely with the previously obtained value by ( somewhat difficult) direct measurement of 28° 55'.9 and the theoretical value of 28° 56'.5.

The proposed foresight is small but it is distinct, and just large enough. The resolution of the eye is about 1' arc and the angular size of the proposed foresight 1'.5 - 2' arc.  This is similar to the outcrop on the skyline at #21 Ballymeanach.

Comments:-

  • The 3rd quarter moon in September would be setting in daylight. Observations might be possible but would presumably be difficult
  • Torbhlaran, Nether Largie and Ford are each for the lower limb of the extreme north position of the moon
  • For the possible use or implication of this see Analysis and Discussion of results