Calibration of Hubble Space Telescope Advanced Camera for Surveys Emission-Line Filters

Abstract

The most commonly used narrowband filters of the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope do not allow the clear delineation of individual emission lines as done with the more narrow field-of-view Wide Field and Planetary Camera. However, we have determined the calibration characteristics that allow separation of the Hα and [N II] lines by means of observations in both the F658N and F660N filters. When coupled with F550M filter continuum measurements, these observations can then be rendered into absolute flux units. A similar set of calibration parameters is also determined for the [O III] emission measured by the F502N filter. The results are expressed in a set of equations that should allow other observers to calibrate their ACS observations in either the wide-field or high-resolution channels of this instrument.

Based in part on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.