In 1995, two intermittent detector features (aka hotspots) particular to the ROSAT HRI have been noticed on the edge of the HRI field. Another hotspot was first seen in 1997 further from the edge of the field which appears in most observations to-date. These features give the appearance of a streak across a portion of the detector corresponding to the satellite wobble. For more specific analysis of the known hotspots please refer to The HRI Calibration Report. Below are the procedures for verifying and removing the features.
HS #1 > xdisplay "rh123456n00.qp[key=(rawx,rawy)][186:697,230:741]" HS #2 > xdisplay "rh123456n00.qp[key=(rawx,rawy)][3380:3891,297:808]" HS #3 > xdisplay "rh123456n00.qp[key=(rawx,rawy)][2753:3252,3065:3564]" OR > xexamine rh...qp[key=(rawx,rawy)] [HS #1, if present, appears as a spot in the lower left; HS #2 in the lower right.]
NOTE: The above coordinates are a small region centered on a hotspot. The object can be verified as a hotspot if the wobbled object in sky coordinates now appears pointlike in detector coordinates.
> timsort "rh....qp[key=(rawx,rawy)]" region: box 441 485 20 20 > vartst > ksplot
Region file: Create a region file with two lines as follows for hotspot #1. FIELD -circle(441,485,20) > qpcopy "rh*_.qp" "rh*_no_hotspot.qp" with the parameter "region" set with the region file name.