System Perturbations

Telescope & Site perturbations:

1. 6 DoF rigid body misalignment of M1M3 (as a single body), M2, and the Camera due to fabrication and installation errors after initial (not AOS) alignment
   • The rigid body displacements due to all sources (including gravity and temperature) will be within the accuracy of the laser tracker (LT). A study on the accuracy of the laser tracker was reported in Document-1187. Results are summarized in the table on page 19. (use the section with Number of Points = 10).
2. 6 DoF rigid body gravitational displacements of M1M3 (as a single body), M2, and the Camera, and the residuals of these displacements after open loop (Look-up-Table) corrections, as a function of zenith angle.
   • see 1. above
3. M1M3 and M2 gravitational shape errors and their residuals after open loop (Look-up-Table) and Force Balance corrections, as a function of zenith angle
   1. M1M3 zenith pointing print through map (04/2014)
      • FEA performed by Ed, with 3D node displacements provided.
      • Surface optimized by Bo using raytracing-corrected bending modes.
   2. M1M3 horizon pointing print through map
   3. M2 zenith pointing print through map
   4. M2 horizon pointing print through map
4. M1M3 and M2 polishing errors (constant shape errors due to fabrication)
5. M1M3 fabrication errors in terms of M3 piston, decenter, and tilt relative to M1.
6. An estimate for dome and mirror seeing in the form of long exposure (15 seconds) OPD or PSF as the function of zenith angle, external wind speed, and air temperature.

7. Temperature and temperature distribution histories and/or statistics for the air inside the dome, as well as for the various components of the system: structure, glass, camera skin.

8. 6 DoF rigid body displacements and shape distortions of M1M3 and M2 due to temperature changes and uneven temperature distributions (the effects on M2 may be negligible)
9. Residual M1M3 thermal deformation after thermal control corrections.

Camera perturbations:

1. 6 DoF rigid body misalignment of L1, L2, L3, and the Filters due to fabrication and installation errors.
2. 6 DoF rigid body gravitational displacements of L1, L2, L3, and the Filters as a function of zenith angle
3. L1, L2, L3, and Filter figuring errors (constant shape errors due to fabrication)
4. L1,L2,L3, and Filter gravitational shape errors as a function of zenith angle (seem to be negligible)
5. Overall detector plane 6 DoF rigid body misalignment and displacement due to
   1. fabrication and installation errors (seem to be negligible)
   2. gravitational effects as a function of zenith angle (seem to be negligible)
   3. thermal effects (detector plane thermal motions)
6. Rafts 6 DoF rigid body misalignment and displacements due to
   1. fabrication and installation errors (sensor profile/height and raft mounting z-position repeatability, albeit current estimates for the later one seem to be small)
   2. gravitational effect as a function of zenith angle (seems to be negligible)
   3. thermal effects (seem to be negligible)
7. Raft shape errors due to
   1. fabrication/polishing errors (seem to be negligible)
   2. gravitational effect as a function of zenith angle (seems to be negligible)
   3. thermal effects (sensor package distortion due to cool down)
8. “PSF” broadening due to charge diffusion and CTE in the CCD and their idiosyncrasies 
9. Internal thermal seeing in the form of long exposure (15 seconds) OPD or PSF, as the function of zenith angle
10. Temperature and temperature distribution histories and/or statistics for the air inside the camera, as well as for the various components of the system: structure and glass.
11. 6 DoF rigid body displacements and shape distortions of L1, L2, L3, and the Filters due to temperature changes and uneven temperature distributions.

Operational Parameters:

1. Altitude histogram from a representative 10 year run (08/2013)

• Raw data provided by Srini.
• Binned by Bo into 90 bins. Note that          altitude angle = 90 degree - zenith angle.