## PointingModelOffsets » History » Version 21

*Lucas Beaufore, 07/12/2013 02:08 PM *

1 | 1 | Lucas Beaufore | h1. Pointing Model Offsets |
---|---|---|---|

2 | 1 | Lucas Beaufore | |

3 | 1 | Lucas Beaufore | 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. |

4 | 2 | Lucas Beaufore | |

5 | 2 | Lucas Beaufore | The following histograms show the distribution of the offsets before trim corrections, and with a trim correction of both addition and subtraction. |

6 | 2 | Lucas Beaufore | |

7 | 2 | Lucas Beaufore | |

8 | 3 | Lucas Beaufore | RA offset with: No correction, addition of a scaled (.0176 arcsec/micron) trim_dy value, subtraction of the scaled trim_dy value |

9 | 3 | Lucas Beaufore | |

10 | 2 | Lucas Beaufore | |!{width:100%}dec_standard.png! |!{width:100%}dec_corrected_y.png! | |!{width:100%}dec_corrected_minus_y.png! | |

11 | 3 | Lucas Beaufore | |

12 | 3 | Lucas Beaufore | Dec offset with: No correction, addition of a scaled (.0176 arcsec/micron) trim_dx value, subtraction of the scaled trim_dx value |

13 | 3 | Lucas Beaufore | |

14 | 2 | Lucas Beaufore | |!{width:100%}ra_standard.png! |!{width:100%}ra_corrected_x.png! | |!{width:100%}ra_corrected_minus_x.png! | |

15 | 4 | Lucas Beaufore | |

16 | 6 | Lucas Beaufore | |

17 | 18 | Lucas Beaufore | The following plots show how adding the trim correction removes the correlation between trim values and the correspoding offsets. The |

18 | 18 | Lucas Beaufore | colors correspond to exposure IDs, approximately time, to help distinguish between exposure sets. |

19 | 1 | Lucas Beaufore | |

20 | 17 | Lucas Beaufore | RA offset corrected with trim_dx value: |

21 | 1 | Lucas Beaufore | |

22 | 19 | Lucas Beaufore | Red = Uncorrected |

23 | 19 | Lucas Beaufore | Blue = Corrected with trim_dx |

24 | 20 | Lucas Beaufore | |!{width:100%}color_ra_correction.png!| |

25 | 1 | Lucas Beaufore | |

26 | 1 | Lucas Beaufore | Declination offset corrected with trim_dy value: |

27 | 17 | Lucas Beaufore | |

28 | 19 | Lucas Beaufore | Red = Uncorrected |

29 | 21 | Lucas Beaufore | Blue = Corrected with trim_dy |

30 | 20 | Lucas Beaufore | |!{width:100%}color_dec_correction.png!| |

31 | 17 | Lucas Beaufore | |

32 | 1 | Lucas Beaufore | |

33 | 1 | Lucas Beaufore | By applying trim corrections, the offsets should no longer include the part of the offset due to hexapod corrections. |

34 | 18 | Lucas Beaufore | 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. |

35 | 11 | Lucas Beaufore | |

36 | 17 | Lucas Beaufore | After applying the correction, the offsets can then be reexamined for correlations with the telescopes position. The plots below illustrate the relations. |

37 | 11 | Lucas Beaufore | |

38 | 14 | Lucas Beaufore | The following two plots show the Declination offsets plotted against the declination of the telescope. The color scale shows the HA of the telescope. |

39 | 15 | Lucas Beaufore | |

40 | 17 | Lucas Beaufore | No correction, correction added |

41 | 17 | Lucas Beaufore | |!{width:100%}dec_teldec_ha.png! |!{width:100%}dec_corrected_teldec_ha.png! | |

42 | 13 | Lucas Beaufore | |

43 | 16 | Lucas Beaufore | |

44 | 12 | Lucas Beaufore | The following two plots show the RA offsets plotted against the declination of the telescope. The color scale shows the HA of the telescope. |

45 | 12 | Lucas Beaufore | |

46 | 17 | Lucas Beaufore | No correction, correction added |

47 | 17 | Lucas Beaufore | |!{width:100%}ra_teldec_ha.png! |!{width:100%}ra_corrected_teldec_ha.png! | |