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Lucas Beaufore, 08/08/2013 11:48 AM


Pointing Model Offsets

In order to study the effects the pointing model may have on the offsets, new offsets were calculated with possible corrections from the effects of the hexapod trim values.

The following histograms show the distribution of the offsets before trim corrections, and with a trim correction of both addition and subtraction.

RA offset with: No correction, addition of a scaled (.0176 arcsec/micron) trim_dy value, subtraction of the scaled trim_dy value

Dec offset with: No correction, addition of a scaled (.0176 arcsec/micron) trim_dx value, subtraction of the scaled trim_dx value

The following plots show how adding the trim correction removes the correlation between trim values and the correspoding offsets. The
colors correspond to exposure IDs, approximately time, to help distinguish between exposure sets.

RA offset corrected with trim_dx value:

Red = Uncorrected
Blue = Corrected with trim_dx

Declination offset corrected with trim_dy value:

Red = Uncorrected
Blue = Corrected with trim_dy

By applying trim corrections, the offsets should no longer include the part of the offset due to hexapod corrections.
As can be seen, adding the correction makes each set of four data points taken in the same position much more horizontal, removing correlation with trim values.

After applying the correction, the offsets can then be reexamined for correlations with the telescopes position. The plots below illustrate the relations.

The following two plots show the Declination offsets plotted against the declination of the telescope. The color scale shows the HA of the telescope.

No correction, correction added

The following two plots show the RA offsets plotted against the declination of the telescope. The color scale shows the HA of the telescope.

No correction, correction added
UserID Name Group attribute list
Starting with a simple row
IT align left
1 Artur Pirozhkov Users align right
2 Vasya Rogov center
3 John Smith Admin
(root)
valign top
4 - Nobody
(anonymous)
valign bottom
id telra ha teldec tel_el az hexapod_x telescope_lut_dx bcam_dx hexapod_y telescope_lut_dy bcam_dy object
222420 339.005983 -44.403458 -75.067998 40.19 166.25 -1140.67 -1140.67306785 581.887 -444.415 -444.424680399 3582.832 Regression Test: HA -3 dec -75
222421 339.005954 -44.248792 -75.067609 40.23 166.29 -1100.7 -1100.70443035 528.046 -408.148 -408.169810085 3554.484 Regression Test: HA -3 dec -75
222422 339.005954 -44.002542 -75.067609 40.28 166.34 -1087.59 -1087.56366465 542.976 -396.458 -396.43149795 3569.16 Regression Test: HA -3 dec -75
222423 339.005983 -43.760417 -75.067637 40.33 166.39 -1075.045 -1075.04353353 493.232 -385.27 -385.266305108 3530.39 Regression Test: HA -3 dec -75
222424 325.755733 -29.903875 -75.060498 42.81 169.84 -343.927 -343.919835158 -3.504 238.474 238.471010059 3375.81 Regression Test: HA -2 dec -75
222425 325.755733 -29.745167 -75.059942 42.83 169.89 -326.932 -326.919643698 -22.494 252.725 252.717421599 3387.304 Regression Test: HA -2 dec -75
222426 325.755779 -29.494625 -75.059942 42.87 169.96 -313.278 -313.271965285 -34.88 263.833 263.837042061 3382.333 Regression Test: HA -2 dec -75
222427 325.755733 -29.252458 -75.059942 42.91 170.03 -299.873 -299.86994067 -53.506 274.747 274.741591957 3359.672 Regression Test: HA -2 dec -75