Since narrow band imaging of a given emission line automatically selects redshift, the one defined by the wavelength tuned, exposure timedrives the depth of the image. Then flux-limited images of a preselected redshift are easily obtained.
A mosaic of images defines the angle covered on the sky, while the wavelength scanned defines the redshift and the redshift interval, covered. In this way, assuming a model of the Universe, it is possible to completely define equal comovile volumes of the Universe at each redshift.
Hα can be separated from [NII]λ658.4 nm by appropiately selecting the TF FWHM and the wavelength interval between images of the same field.
The number of sources per image, given the redshift and the depth, can be estimated by using a luminosity function plus evolution models. Then the desired number of sources will define the number of fields to be observed.
The morphological identification needed for metallicity studies will be done via an auxiliary broad band survey, that is part of OTELO preparatory activities. This broad band survey will also serve to distinguish stars and QSO in OTELO.
Finally, the broad band survey will provide an approximate redshift for each source. Then the emission line observed can be unambiguously identified.
Given the depth of OTELO survey, not only Hα emitters at z<=0.40 will be observed, but also many sources at redshifts up to 1.5 for the emission lines [OIII]λ500.7 nm, Hbeta and [OII]λ372.7 nm. These emitters will provide an important database to study the evolution of galaxies.
OTELO
Home PageLast update December 1, 2005, by Héctor Castañeda