The CalUnitSystem (or Calibration Unit) is the ARGOS source used for AO calibration in day-time.

It creates 3 beams that mimics the 3 LGS beams: 532nm narrow band filter, same off-axis aberrations of M1 introduced using an hologram. It also provides an on-axis NGS source (actually a fiber in the ASM vertex re-imaged by the CalUnitSystem optics )

The optics are moved in the telescope's prime focus by a dedicated swing arm. The light is provided by 3 LED sources (for the off-axis beams) and a white source (for the on-axis beam)

It is developed and maintained by MPIA

List of devices of this kind

Name	Serial Number	Location
Calibration Unit DX	DXCU	LBTCRingExtensionDX
Calibration Unit SX	SXCU	LBTCRingExtensionSX

Documentation

Informations about HowToSetupCalibrationUnit can be found in the ARGOS ListOfHowTo.

See also HowToSetupHexapodForCalibrationUnit for the history of best hexapod positions

Documentation about the SwingArm and CalUnitSystem optics can be here: https://wiki.lbto.org/Software/WikiHardware_overview

Installation and maintenance

describe what is needed to put a new device of this kind into operation state: configuration, firmware uploading, software modifications, ...