Optimizing point-source parameters for scanning satellite surveys

Abstract

We describe a method for deriving the position and flux of point and compact sources observed by a scanning survey mission. Results from data simulated to test our method are presented, which demonstrate that at least a 10-fold improvement is achievable over that of extracting the image parameters, position and flux, from the equivalent data in the form of pixel maps. Our method achieves this improvement by analysing the original scan data and performing a combined, iterative solution for the image parameters. This approach allows for a full and detailed account of the point-spread function, or beam profile, of the instrument. Additionally, the positional information from different frequency channels may be combined to provide the flux-detection accuracy at each frequency for the same sky position. Ultimately, a final check and correction of the geometric calibration of the instrument may also be included. The {\it Planck} mission was used as the basis for our simulations, but our method will be beneficial for most scanning satellite missions, especially those with non-circularly symmetric point-spread functions.Comment: 13 pages, 14 figures, 3 tables, accepted for publication by MNRA

A fast 2D image reconstruction algorithm from 1D data for the Gaia mission

“…It takes as initial values for the image parameters of position and magnitude, those values extracted from the reconstructed image, together with the original transit data and PSF/LSF data. The analysis proceeds via a least squares approach as explained in [11]; the primary difference being that in addition to position and magnitude, the proper motions and differential parallaxes are also solved for.…”