We have created two databases of corrected pointing information with which users can coalign any XRT images with those from other instruments. The databases are updated automatically every week and are distributed, with programs for interfacing with the databases, as a part of the Solar Software.
One of the databases is derived from Hinode's Sun sensors (UFSS) output and the other is the result of cross-correlation between XRT images and AIA EUV images. While the pointing information from the cross-correlation method provides better correction in many cases, the information from the UFSS tends to yield more consistent coalignment results. The interface programs use the latter as default to avoid large errors which occasionally are returned by the cross-correlation technique.
The correction in the UFSS method includes: (i) offset between UFSS and XRT G-band optics; (ii) offset between XRT G-band and X-ray optics; (iii) roll angle difference between XRT and SDO; and (iv) roll angle difference between XRT and UFSS.
We also present some new calibration methods which drastically improved the pointing correction of the XRT data.