== 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 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 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 daytime, this maybe 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 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**