Astrophotography and image processing techniques were introduced as a solution to the problem of determining the beginning dawn time. The results of some research were different with Ministry Religion Affairs and raise doubts for some Muslims then need to require re-verification. Astrophotography, a special method of photography, is recording images of astronomical objects such as the moon, stars, and other celestial bodies. The astrophotography technique is used for the object of the emergence of dawn rays with the assumption that the image before and after the appearance of dawn will have different pixel values. Then, a combination of astrophotography and image processing techniques is used to analyze pixel changes to identify the beginning of dawn. The image processing technique used is edge detection. Edges correspond to changes in pixel intensity. The easiest way to detect the beginning of dawn is to apply a filter that highlights this change in intensity in both directions: horizontal (x) and vertical (y). An edge detection filter "sadiq filter" is modeled as a result of the development of the Sobel and canny filters. Sadiq filter has been applied to the dawn data in Labuan Bajo and can distinguish the image before and after dawn well. It is hoped that the "sadiq filter" can be developed into a filter from an application or software so that it can be used by the wider community to solve the problem of determining the early morning prayer time. An edge detection filter "sadiq filter" is modeled as a result of the development of the Sobel and canny filters. Sadiq filter has been applied to the dawn data in Labuan Bajo and can distinguish the image before and after dawn well. It is hoped that the "sadiq filter" can be developed into a filter from an application or software so that it can be used by the wider community to solve the problem of determining the early morning prayer time. An edge detection filter "sadiq filter" is modeled as a result of the development of the Sobel and canny filters. Sadiq filter has been applied to the dawn data in Labuan Bajo and can distinguish the image before and after dawn well. It is hoped that the "sadiq filter" can be developed into a filter from an application or software so that it can be used by the wider community to solve the problem of determining the early morning prayer time.