11.5.3 COS Apertures
This article describes the apertures available for COS observations. |
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Format definitions
Boldface type indicates the name of an APT parameter or a value for a parameter.
Black text indicates an important note.
Magenta text indicates available but unsupported parameters (requires prior approval from STScI).
Red text indicates restricted parameters (for STScI use only).
Brown text indicates text file parameters.
Items in brackets - <value> - are required values.
Items in square brackets - [<value>] - are optional.
Science observations should use the PSA or BOA apertures. The BOA aperture is the same size as the PSA but contains a neutral-density filter that attenuates the source by a factor of ~200. The WCA is intended for wavelength calibrations using the WAVE target.
Table 11.8: COS Apertures
Aperture | Definition | Size | Usage |
PSA | Primary Science Aperture | 2.5 arc seconds | Default science aperture |
BOA | Bright Object Aperture | 2.5 arc seconds | Contains neutral density filter (ND2) for bright objects |
WCA | Wavelength Calibration Aperture | 20 microns (dispersion) × 100 microns | Wavelength Calibrations |
Restricted FCA
11.5.2 COS Spectral Elements and Central Wavelengths
11.5.4 COS WAVECAL Exposure Parameters
11.5.5 COS Coordinate System