LBC Collimation Models

The table below will be used to store relevant facts about the recent collimation models for LBC SX and DX.
  • Column 1: the date on which the data for the collimation model were taken
  • Column 2: the name of the file which contains the data. These files are in /home/lbcobs/Collimation/new unless otherwise noted. The format is X Y Z RX RY elevation temperature where X,Y,Z,RX,RY are the positions of the primary mirror (MIRRORX, MIRRORY, MIRRORZ, MIRRORRX, MIRRORRY in the LBC headers). Z is corrected by 0.8 if the collimation data are from pupil images. If instead from in-focus images, there is no need for a Z correction. elevation is TELALT in the headers and temperature is LBTTEMP in the headers. LBTTEMP is the ambient temperature at the SMT, not what is required for a good modelling of the temperature dependence of the collimation model. We need to implement either one of the truss temperatures or the glass temperature, which is what PSF uses to adjust the collimation model for temperature. This data file may be produced by the IRAF task which is found in /home/okuhn/reduce/ on the mountain workstations and runs hsel to list the aforementioned header values and then adds 0.08 to the MIRRORZ value.
  • Column 3: Collimation table output from the IDL program, which is in /home/lbcobs/Collimation/new/. Current and old collimation data tables are in /home/telescope/TCS/Configuration/PSF/ and old collimation tables are also in /home/lbcobs/Collimation. Data are scaled to T=0C, then are fit by a 3rd order polynomial for each of the degrees of freedom: X,Y,Z,RX,RY. The output file has 2 lines of comments, the table temperature (0.0 C), 2 more lines of comments and then 3 lines of linear, quadratic (0) and cubic (0) temperature coefficients, 1 line containing the Global Offsets and 3 lines containing the linear, quadratic and cubic polynomial coefficients.
    • The temperature dependence is assumed to be linear.
      • X(T) = X(T=0) - 0.08 * T
      • Y(T) = Y(T=0) - 0.14 * T
      • Z(T) = Z(T=0) + 0.10 * T
    • The global offsets are set to zero initially, but may be changed by hand. Both SX and DX Z global offsets may need to be adjusted when the LBC hubs are moved from their summer to winter positions. SX global offsets will also be changed to adjust pointing so that LBC Blue co-points with LBC-Red.
  • Column 4: Average temperature over which the collimation data were taken.
  • Column 5: Plots of the model and the raw data (not scaled to T=0). The thick solid line is the model for T=0 and the dashed lines represent the model for different temperatures from -10 C to +10 C in increments of 2 deg C. The T=-10 curve is drawn with a thin solid line for clarity. The plots are created with the sm macro, colimits2.mac in /home/kuhn/LBT/LBC/Collimation/. Run sm and load this macro. Then plot the model and data with the command collim CollimationTable Data File.

Date Data File Collimation Table Avg. Temperature Plot Comments
20100318 no new data DXPMLBCCollimation.dat (current)     new Z GO for hub move, new Y GO; Y=-0.50, Z=1.584
20100227 no new data DXPMLBCCollimation.dat     Red Hub moved +1.6mm
20100217 no new data DXPMLBCCollimation.dat     New DX Magic, Global Offsets: dX=-3.042 dY=0 dZ=-0.657 dRX=0 dRY=+32.68
20100217 no new data DXPMLBCCollimation.dat     New DX Hardpoints
20090911 CollimationRed20090911.txt DXPMLBCCollimation20090911.dat 9.4 C DX20090911.pdf  
20090911 CollimationBlue20090911.txt SXPMLBCCollimation.dat (current) 9.4 C SX20090911.pdf  
20090911 CollimationBlue20090911.txt SXPMLBCCollimation20090911.dat 9.4 C SX20090911.pdf  

20090418 SXPMLB SXPMLBCCollimation.20090418.dat xx      
20090320 RedCollim0320.oout (/home/LBTO/kuhn/20090320/RedCollim0320.dat) DXPMLBCCollimation.20090320.dat 5 DX20090320.pdf    
20090320 BluCollim0320.oout (/home/LBTO/kuhn/20090320/BluCollim0320.dat) SXPMLBCCollimation.20090320.dat 5 SX20090320.pdf    

-- OlgaKuhn - 24 Mar 2010

I Attachment Action Size Date Who Comment
DX20090320.pdfpdf DX20090320.pdf manage 7 K 30 Mar 2010 - 21:53 OlgaKuhn DX Collimation 20090320
DX20090911.pdfpdf DX20090911.pdf manage 9 K 24 Mar 2010 - 18:43 OlgaKuhn DX Collimation - plot of model (with temperature prediction) and data
SX20090320.pdfpdf SX20090320.pdf manage 7 K 30 Mar 2010 - 21:52 OlgaKuhn SX Collimation 20090320
SX20090911.pdfpdf SX20090911.pdf manage 9 K 24 Mar 2010 - 18:44 OlgaKuhn SX Collimation - plot of model (with temperature prediction) and data
Topic revision: r5 - 30 Mar 2010, OlgaKuhn
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