Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.stsci.edu/instrument-news/handbooks/wfpc2/W2_77.html
Дата изменения: Wed Jul 24 04:09:09 1996
Дата индексирования: Tue Feb 5 06:03:36 2013
Кодировка:
Поисковые слова: m 43

Emission Line Observations of Galaxy Nuclei

Observation Strategies

7.11 Emission Line Observations of Galaxy Nuclei

Saturation is a common problem for narrow band filter images of galaxy nuclei. Often the surface brightness of the emission line is estimated from ground-based images with 1" resolution; sometimes line fluxes are quoted for apertures several arcseconds in radius. However, at HST resolution, much of this flux may occur in a single unresolved spot at the galaxy nucleus, thus leading to saturated images. Observers should be cautious and consider this possibility when estimating exposure times.