36,319 research outputs found
Photo-z Performance for Precision Cosmology II : Empirical Verification
The success of future large scale weak lensing surveys will critically depend
on the accurate estimation of photometric redshifts of very large samples of
galaxies. This in turn depends on both the quality of the photometric data and
the photo-z estimators. In a previous study, (Bordoloi et al. 2010) we focussed
primarily on the impact of photometric quality on photo-z estimates and on the
development of novel techniques to construct the N(z) of tomographic bins at
the high level of precision required for precision cosmology, as well as the
correction of issues such as imprecise corrections for Galactic reddening. We
used the same set of templates to generate the simulated photometry as were
then used in the photo-z code, thereby removing any effects of "template
error". In this work we now include the effects of "template error" by
generating simulated photometric data set from actual COSMOS photometry. We use
the trick of simulating redder photometry of galaxies at higher redshifts by
using a bluer set of passbands on low z galaxies with known redshifts. We find
that "template error" is a rather small factor in photo-z performance, at the
photometric precision and filter complement expected for all-sky surveys. With
only a small sub-set of training galaxies with spectroscopic redshifts, it is
in principle possible to construct tomographic redshift bins whose mean
redshift is known, from photo-z alone, to the required accuracy of 0.002(1+z).Comment: 7 pages, 5 figures, accepted for publication in MNRA
Hypermedia support for argumentation-based rationale: 15 years on from gIBIS and QOC
Having developed, used and evaluated some of the early IBIS-based approaches to design rationale (DR) such as gIBIS and QOC in the late 1980s/mid-1990s, we describe the subsequent evolution of the argumentation-based paradigm through software support, and perspectives drawn from modeling and meeting facilitation. Particular attention is given to the challenge of negotiating the overheads of capturing this form of rationale. Our approach has maintained a strong emphasis on keeping the representational scheme as simple as possible to enable real time meeting mediation and capture, attending explicitly to the skills required to use the approach well, particularly for the sort of participatory, multi-stakeholder requirements analysis demanded by many design problems. However, we can then specialize the notation and the way in which the tool is used in the service of specific methodologies, supported by a customizable hypermedia environment, and interoperable with other software tools. After presenting this approach, called Compendium, we present examples to illustrate the capabilities for support security argumentation in requirements engineering, template driven modeling for document generation, and IBIS-based indexing of and navigation around video records of meetings
- …