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PointingModelOffsets » History » Version 26

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

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h1. Pointing Model Offsets
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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.
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The following histograms show the distribution of the offsets before trim corrections, and with a trim correction of both addition and subtraction.
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RA offset with: No correction, addition of a scaled (.0176 arcsec/micron) trim_dy value, subtraction of the scaled trim_dy value
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|!{width:100%}dec_standard.png! |!{width:100%}dec_corrected_y.png! | |!{width:100%}dec_corrected_minus_y.png! |
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Dec offset with: No correction, addition of a scaled (.0176 arcsec/micron) trim_dx value, subtraction of the scaled trim_dx value
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|!{width:100%}ra_standard.png! |!{width:100%}ra_corrected_x.png! | |!{width:100%}ra_corrected_minus_x.png! |
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The following plots show how adding the trim correction removes the correlation between trim values and the correspoding offsets. The 
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colors correspond to exposure IDs, approximately time, to help distinguish between exposure sets.
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RA offset corrected with trim_dx value:
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Red = Uncorrected
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Blue = Corrected with trim_dx
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|!{width:100%}color_ra_correction.png!|
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Declination offset corrected with trim_dy value:
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Red = Uncorrected
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Blue = Corrected with trim_dy
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|!{width:100%}color_dec_correction.png!|
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By applying trim corrections, the offsets should no longer include the part of the offset due to hexapod corrections.
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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.
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After applying the correction, the offsets can then be reexamined for correlations with the telescopes position. The plots below illustrate the relations. 
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The following two plots show the Declination offsets plotted against the declination of the telescope. The color scale shows the HA of the telescope.
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No correction, correction added
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|!{width:100%}dec_teldec_ha.png! |!{width:100%}dec_corrected_teldec_ha.png! |
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The following two plots show the RA offsets plotted against the declination of the telescope. The color scale shows the HA of the telescope.
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No correction, correction added
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|!{width:100%}ra_teldec_ha.png! |!{width:100%}ra_corrected_teldec_ha.png! |
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|_.UserID      |_.Name          |_.Group     |_. attribute list   |
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|Starting with | a              |   simple   |row                 |
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|\3=.IT                                      |<. align left       |
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|1             |Artur Pirozhkov |/2.Users    |>. align right      |
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|2             |Vasya Rogov     |=. center   |
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|3             |John Smith      |Admin
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                                 (root)      |^. valign top       |
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|4             |-               |Nobody
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                                 (anonymous) |~. valign bottom    |
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|_.id   |_.telra         |_.ha 	    |_.teldec 	|_.tel_el 	|_.az 	|_.hexapod_x 	|_.telescope_lut_dx 	|_.bcam_dx 	|_.hexapod_y 	|_.telescope_lut_dy 	|_.bcam_dy 	|_.object
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|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
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|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
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|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
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|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
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|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
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|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
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|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
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|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|