Prominence PA in the SDO/AIA 171 Å image (left) and STEREO A/EUVI 171 Å image (right) at the same time on May 25, 2012. The EUVI image is in log-scale for clarity. Different features are marked with circles in different colors, and circles of the same color in the two images represent the same structures. The diameter of these circles is 8 arcsec (about 5800 km). The dotted lines are the Carrington coordinate latitude and longitude lines, using the latitudes and longitudes of the three points F1, F2, and F3. The LOS of STEREO A in the left picture is along the latitude, and the dashed lines and arrows in the right image show the LOS of SDO.