4/8 Point Test

This test measures the basic azimuth and elevation offsets of the structure. The basic idea is to run tracks that are horizontal or vertical where the majority of the correction will be in azimuth or elevation. These corrections are then applied to the structure and the test may be run again to refine the corrections.

4 Point Test

Run trajectories at the cardinal points. Select objects that are close to the center of the tracker for best results. The cardinal points are

Azimuth	Dec
0.00	65.43	north trajectory
65.43	38.53	east trajectory
180.00	-4.30	south trajectory
294.50	38.53	west trajectory

Record the actual true azimuth of the structure and the Ra/Dec offsets required to get the object to the center of the field.

The north and south trajectories should require close to the same offset as should the east and west trajectories. The north/south Ra correction should be similar to the east/west Dec correction and it should be applied to the azimuth correction , while the north/south Dec should be similar to the east/west Ra and is applied to the elevation correction.

The correction should be applied with reversed sign to the AOFF and EOFF values in the source file <trunk>/legacy/etc/structureModel.dat. This file should then be installed and the legacyServer restarted to pick up the change. The values may be changed temporarily in the file /opt/het/hetdex/etc/conf/structureModel.dat, however, you will need to use sudo to override the read only file permission.

8 Point Test

Basically the same as the 4 Point test but with more points. Close to the cardinal directions is useful but not necessary. The points should be spaced about equally in azimuth. [This procedure will require revision after we have performed it a few times.]