Data Analysis of AO Images in Crowded Stellar Fields

Deep, Atul

It is expected that several new Extremely Large Telescopes (E-ELT, TMT & GMT) will see first light towards the end of this decade. The large aperture size of these telescopes ( > 20m) along with their adaptive optics systems (like MCAO, GLAO, SCAO etc ) will allow us to image astrophysical objects with unprecedented very high angular resolution. However, to extract full scientific information from these systems is going to a very challenging task because of complex shape of AO point spread function (PSF) and will therefore require careful data reduction techniques. The main complexity of AO images is that the correction is never perfect and the PSF always has a complex residual halo around the central core which contains a large fraction of the light. The variations in seeing over short periods of time and anisoplanatism effects create strongly time dependent effects in the PSF. We create simulations of crowded stellar fields using PSFs from a MCAO (multiconjugate AO) system MAORY (a Multi-Conjugate AO system, currently a Phase A study at ESO) to perform our analysis. For SCAO (single-conjugate AO) mode we use analytic code PAOLA to obtain our PSFs. Photometry is then performed on these simulated images using current photometric packages like Starfinder and Daophot to test photometric accuracy achieved in different crowding regimes, effect of anisoplanatism and seeing conditions.

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