Table 1: List of objects detected in the first data set (cf. Figs. 6 and 12) with eccentricity larger than 0.84, i.e. good arc candidates. Objects with an eccentricity larger than 0.9, i.e. objects 1 to 6 are very good candidates.

	Mass center	Size (Pixel)	Eccentricity
1	(593, 749)	768	0.978
2	(188, 177)	603	0.956
3	(595, 899)	143	0.943
4	(794, 440)	241	0.942
5	(320, 144)	196	0.928
6	(842, 901)	181	0.901
7	(141, 328)	27	0.876
8	(130, 819)	95	0.871
9	(165, 61)	52	0.866
10	(223, 871)	86	0.864
11	(488, 103)	65	0.854
12	(151, 659)	32	0.845
13	(677, 260)	44	0.840