Table 1: Log of the Chandra and XMM-Newton observation used in this paper.

Spacecraft	Object	Start day	Start time	On-source
			(UT)	time (ks)
XMM-Newton	4U 1700+24	11 Aug. 2002	15:38:22	5.96
XMM-Newton	4U 1700+24	07 Mar. 2003	01:08:08	5.02
XMM-Newton	4U 1700+24	09 Mar. 2003	01:03:49	8.97
XMM-Newton	4U 1700+24	13 Aug. 2003	15:23:12	13.6
Chandra	4U 1700+24	23 Apr. 2005	02:45:03	1.15
Chandra	4U 1954+319	18 Jan. 2006	20:24:30	1.18