== P2.6	Measurement of NCPA == 
•	**Phase**		:	2  
•	**Status**		: 	Draft	 
•	**Category**		: 	Daytime calibration (C3)
•	**Recurrence**	: 	after instrument installation at telescope platform
•	**Duration**		: 	10 days
**Description**
•	Measure the Non-Common Path Aberrations (NCPA).
**Prerequisites**
•	Use of Argos swing arm / RR mounted on the SX side. SHARK-NIR aligned to telescope.
**Procedure**
•	In closed-loop, we optimize the PSF shape on SCICAM using the trial & error algorithm used by the LBTO team during LUCI calibrations changing M2 reference shape applying modes coefficients (this is the baseline approach).
•	We also perform the phase-diversity tests using the same light source and look at the NCPA output produced (in case the NCPA produced by the baseline approach is not stable enough for a longer period and/or if more correction seems necessary for high contrast).
•	Depending on the two results and the quality of PSF, we may choose one or the other or the combination of both.
* There is also the NCPA test to be performed using the Wollaston prism + direct imaging in dual-band imaging mode. In the daytime, this may be performed using the ARGOS swing arm calibration unit light source (for zenith, and if required using RR on other elevation angles)
•	Note that we may do this for different elevation angles.


**Success criteria**
•	NCPA estimated and applied on the ASM (need to define a quantitative value?)
•	Satisfactory PSF quality with closed-loop and get a new and improved daytime telescope model for SHARK-NIR?

**Notes**
•	See activity 8.1 in AD4 for more details. 
**LBTO support**
* Authorize SHARK-NIR on the SX side.
* Permission to use the Argos Swing Arm.
* When not using Argos swing arm and for different elevation angle tests, RR will be required on the SX side.
* Support from LBT SW Team, LBTI/Arcetri team to run SOUL AO


**Associated SHARK-NIR personnel**


**Date performed and by whom**