Title:
PSF-fitting techniques for crowded field 3D spectroscopy
Authors:
Martin M. Roth
Abstract:
In retrospect, it was the advent of the CCD as a linear, high dynamic range
panoramic detector which made it possible to overcome the source confusion
problem for stellar photometry, e.g. in star clusters, local group galaxies,
etc. The ability of accurately sampling the point-spread-function (PSF) in
two dimensions and to use it as a template for fitting severely overlapping
stellar images is of fundamental importance for crowded-field photometry,
and has thus become the foundation for the determination of accurate CMDs
of globular clusters and the study of resolved stellar populations in nearby
galaxies.
Analogous to CCDs, the introduction of integral field spectrographs has opened
a new avenue for crowded-field 3D spectroscopy, which benefits in the same
way from PSF-fitting techniques as does CCD photometry.
I shall present our experience with sampling the PSF with 3D spectroscopy,
review the effects of atmospheric refraction, discuss background subtraction
problems, and present several science applications as obtained from observations
with the PMAS and VIMOS instruments. I shall conclude with an outlook into
science cases with AO-assisted 3D spectroscopy and future prospects of Extremely
Large Telescopes.