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Active Optics

Aaron Roodman sent information that briefly describes the variable in the active optics control in the telemetry database sections donut_ana (and a couple in donut_summary). Probably the description of these variables in the DECam documentation is otherwise out of date.

The telemetry can be found at Telemetry

This note summarizes the useful AOS variables in the SISPI DB:

Table: donut_summary

sudz - delta z from Z4 average values (currently used by AOS for hexapod defocus)
n_donuts - number of donuts used by AOS

Table: donut_ana

doXX variables are from donut_ana algorithm, have -1 * measured values, units are microns for x,y,z and arcsec for tip/tilt:

dodz - delta z (focus)
dodx - delta x (x decenter)
dody - delta y (y decenter)
doxt - x tip/tilt
doyt - y tip/tilt

dodzErr - estimated error in dodz
dodxErr - estimated error in dodx
dodyErr - estimated error in dody
doxtErr - estimated error in doxt
doytErr - estimated error in doyt

Variables below are measured wavefronts from donut_ana algorithm. Units for z4 are in microns of defocus, and units for deltas of other Zernike terms are in Waves at 700nm. Units for thetax,y are in microns/mm for z4 and waves/mm for other Zernikes. All values are from a comparison against the default wavefront meshes. See Roodman, SPIE 2014 for more details.

zdelta - measured delta z4 (defocus Zernike) wavefront
zthetax - measured thetax of z4 wavefront
zthetay - measured thetay of z4 wavefront
zdeltaErr - error estimate for zdelta
zthetaxErr - error estimate for zthetax
zthetayErr - error estimate for zthetay
zmeandeltaBefore - mean of deltaz distribution before fit to default wavefront
zrmsdeltaBefore - rms of deltaz distribution before fit to default wavefront
zmeandeltaAfter - mean of deltaz distribution after fit
zrmsdeltaAfter - rms of deltaz distribution after fit

variables repeated for other Zernike terms, z5,z6: Y,X Astigmatism and z7,z8 Y,X Coma. Currently z9,z10 Trefoil and z11 Spherical terms are unfilled.