Table 3:

Global astrometric solution for WFI CCD mosaics.

Sky	Zero-point	(RA, Dec)-UCAC2		UCAC2
path	offset before G.S.	before G.S.	after G.S.	stars
	cos
Year	mas mas	mas mas	mas mas
2008	-13   -04	112   107	59   58	6001
2009	-09   -01	112   103	58   55	4693
2010	-03   -03	133   126	59   57	11013
2011	-08   -03	134   129	61   59	8988
2012	-06   -05	139   131	62   61	7563
2013	-03   -04	145   141	63   62	6068
2014	-06   +02	135   138	60   60	6439
2015	-06   -03	100   098	57   57	7524

Notes. Tangent plane technique results. Zero point position offsets were computed from averaged observed minus UCAC2 star position differences, before applying the global mosaic solution procedure (G.S.). Due to the tangent plane technique, by definition they are zero after G.S. process. The ( , )s of tangent plane technique solutions refer to observed minus UCAC2 positions computed before and after the G.S. procedure. The last column is the number of used UCAC2 reference stars (see details in Sect. 4.3).