The Space multi-band Variable Object Monitor(SVOM) is a proposed Chinese astronomical satellite,dedicated to the detection,localization and measurement of gamma-ray bursts(GRBs) on a cosmological scale.An efficient al...The Space multi-band Variable Object Monitor(SVOM) is a proposed Chinese astronomical satellite,dedicated to the detection,localization and measurement of gamma-ray bursts(GRBs) on a cosmological scale.An efficient algorithm is developed for the purpose of onboard star extraction from the CCD images obtained with the Visible Telescope(VT) onboard the SVOM.The CCD pixel coordinates of the reference stars will be used to refine the astronomical position of the satellite,which will facilitate triggering rapid ground-based follow-up observations of the GRBs.In this algorithm,the image is divided into a number of grid cells and the "global" pixel-value maximum within each cell is taken as the first-guess position of a "bright" star.The correct center position of a star is then computed using a simple iterative method.Applying two additional strategies,i.e.,scanning the image only by even(or odd) lines or in a black-white chess board mode,we propose to further reduce the time to extract the stars.To examine the efficiency of the above algorithms,we applied them to the experimental images obtained with a ground-based telescope.We find that the accuracy of the astronomical positioning achieved by our method is comparable to that derived by using the conventional star-extraction method,while the former needs about 25 times less CPU time than the latter.This will significantly improve the performance of the SVOM VT mission.展开更多
基金supported by the National Basic Research Program of China (Grant No. 2009CB8-24800)the National Natural Science Foundation of China (Grant Nos. 10878019 and 10673014)
文摘The Space multi-band Variable Object Monitor(SVOM) is a proposed Chinese astronomical satellite,dedicated to the detection,localization and measurement of gamma-ray bursts(GRBs) on a cosmological scale.An efficient algorithm is developed for the purpose of onboard star extraction from the CCD images obtained with the Visible Telescope(VT) onboard the SVOM.The CCD pixel coordinates of the reference stars will be used to refine the astronomical position of the satellite,which will facilitate triggering rapid ground-based follow-up observations of the GRBs.In this algorithm,the image is divided into a number of grid cells and the "global" pixel-value maximum within each cell is taken as the first-guess position of a "bright" star.The correct center position of a star is then computed using a simple iterative method.Applying two additional strategies,i.e.,scanning the image only by even(or odd) lines or in a black-white chess board mode,we propose to further reduce the time to extract the stars.To examine the efficiency of the above algorithms,we applied them to the experimental images obtained with a ground-based telescope.We find that the accuracy of the astronomical positioning achieved by our method is comparable to that derived by using the conventional star-extraction method,while the former needs about 25 times less CPU time than the latter.This will significantly improve the performance of the SVOM VT mission.
