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We present descriptions of the alignment and calibration tests of thePathfinder, which achieved first light during our 2013 commissioning campaignat the LBT. The full LINC-NIRVANA instrument is a Fizeau interferometric imagerwith fringe tracking and 2-layer natural guide star multi-conjugate adaptiveoptics (MCAO) systems on each eye of the LBT. The MCAO correction for each sideis achieved using a ground layer wavefront sensor that drives the LBT adaptivesecondary mirror and a mid-high layer wavefront sensor that drives a Xinetics349 actuator DM conjugated to an altitude of 7.1 km. When the LINC-NIRVANA MCAOsystem is commissioned, it will be one of only two such systems on an 8-metertelescope and the only such system in the northern hemisphere. In order tomitigate risk, we take a modular approach to commissioning by decoupling andtesting the LINC-NIRVANA subsystems individually. The Pathfinder is theground-layer wavefront sensor for the DX eye of the LBT. It uses 12 pyramidwavefront sensors to optically co-add light from natural guide stars in orderto make four pupil images that sense ground layer turbulence. Pathfinder is nowthe first LINC-NIRVANA subsystem to be fully integrated with the telescope andcommissioned on sky. Our 2013 commissioning campaign consisted of 7 runs at theLBT with the tasks of assembly, integration and communication with the LBTtelescope control system, alignment to the telescope optical axis, off-skyclosed loop AO calibration, and finally closed loop on-sky AO. We present theprogrammatics of this campaign, along with the novel designs of our alignmentscheme and our off-sky calibration test, which lead to the Pathfinder's firston-sky closed loop images.

Pathfinder first light: alignment, calibration, and commissioning of the LINC-NIRVANA ground-layer adaptive optics subsystem