Test of the Detection of Weak Stars by Means of the Overlap of Their Several Images Obtained with A CCD

A method for observing the weak sources hidden in the strong background is presented in this paper by making use of the advantages of the wider dynamic range and convenient data processing of a CCD During the observation, before the background glow makes the plate of the CCD be saturated stop the exposure and store the image in the computer system. The plate exposures to the background glow several times according to the above-mentioned method and then the images are overlapped in the computer. The weak sources appear after the background elimination. From the observational test and quantitative estimate, the results show that the signal noise ratio can increase by 265% when 10 images are overlapped and the observed results are in accordance with the perfect ones well.