  Our aim is to identify and trace the X-ray Bright Points (XBPs) over the disk
and use them as tracers to determine the coronal rotation. This investigation
will help to clarify and understand several issues: whether (i) the corona
rotates differentially; (ii) the rotation depends on the sizes of the XBPs; and
(iii) dependence on phases of the solar magnetic cycle. We analysed the daily
full-disk soft X-ray images observed with (i) X-Ray Telescope (XRT) on-board
the Hinode mission during January, March and April, 2007 and (ii) Soft X-ray
Telescope (SXT) on-board the Yohkoh from 1992 to 2001 using SSW in IDL. We have
used the tracer method to trace the passage of XBPs over the solar disk with
the help of overlaying grids and derived the sidereal angular rotation velocity
and the coordinates (latitude and longitude) of the XBPs. We have determined
the position of a large number of XBPs both in Hinode/XRT and Yohkoh/SXT images
and followed them over the solar disk as a function of time. We derived the
coronal sidereal angular rotation velocity and compared it with heliocentric
latitude and as a function of solar activity cycle. In addition, we measured
the sizes of all the XBPs and related them with the coronal rotation. The
important results derived from these investigations are: (i) the solar corona
rotates differentially like the photosphere and chromosphere; (ii) the sidereal
angular rotation velocity is independent of the sizes of the XBPs; (iii) the
sidereal angular rotation velocity does not depend on phases of the solar
magnetic cycle; and (iv) the differential rotation of the corona is present
throughout the solar magnetic cycle.
