Wild Heerbrugg GSP1 Roelofs prism
Roelofs prism for mounting on the NT1, T16 and T21.
Obtained from the US
Product details: Wild Heerbrugg GSP1 Roelofs prism | Wild Heerbrugg | Instrument acc. | |
The Roelofs prism was invented by Dutch professor of geodesy, Roelofs. Using a set of two prism at right angles to each other it will divide the image of the sun into four separate images that overlap. Using the resulting four sun pattern it is easy to point the cross hairs of the theodolite at the centre of the sun making the sun azimuth much easier to perform. It also avoids the computation of the correction for the sun diameter which needs to be performed with an ordinary dark filter.
Although the pictures show three Roelofs prisms, two old ones (with serials) and one new one (leather bag, labeled GSP1), I now only own two. The third has gone to the Maritime Institute at Terschelling for the sun azimith measurements. The students made a plastic converter to allow mounting the prism onto the modern Leica and Sokkia total station.
More information / other collections
GSP1
Data sheet
- Serialnumber
- 793
- Size instrument (l x w x h) in m
- 0.06 x 0.05 x 0.04
- weight instrument in kg
- 0.07
- Size case (l x w x h) in m
- 0.09 x 0.08 x 0.05
- weight case & in kg
- 0.13
- country obtained from
- United States
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Roelofs prism for mounting on the NT1, T16 and T21.
Obtained from the US
Product details: Wild Heerbrugg GSP1 Roelofs prism | Wild Heerbrugg | Instrument acc. | |