7.1.1 Identify Science Requirements and Define ACS Configuration
First and foremost, of course, you must identify the science you wish to achieve with ACS. Basic decisions you will need to make are:
- Nature of target
- Filter selection
As you choose your science requirements and work to match them to the instrument's capabilities, keep in mind that those capabilities differ greatly depending on whether you are observing in the optical or near-UV with the CCD, or in the far-UV using the MAMA detector. Trade-offs are described in Table 7.1
Table 7.1: Science decision guide.
Decision |
Choices |
Tradeoffs |
Field of view |
Camera Filter selection |
WFC: 202 x 202 arcseconds HRC: 29 x 26 arcseconds SBC: 35 x 31 arcseconds |
Spectral response |
Camera Filter selection |
WFC: 3700-11,000 Å HRC: 2000-11,000 Å SBC: 1150-1700 Å |
Spatial resolution |
Camera |
WFC: ~50 milliarcsecond pixels HRC: ~ 27 milliarcsecond pixels SBC: ~32 milliarcsecond pixels |
Filter selection |
Camera |
WFC: broad, medium & narrow band, ramps HRC: Visible, UV, ramp middle sections |
Spectroscopy |
Camera Spatial resolution Field of view Wavelength range |
Grism (G800L): WFC and HRC Prism (PR200L): HRC Prism (PR110L, PR130L): SBC |
Polarimetry |
Filters |
UV polarizers combine with Wheel 2 filters VIS polarizers combine with Wheel 1 filters |
Coronagraphy |
Filter selection |
Coronagraphic imaging available with HRC only |
.
Imaging
For imaging observations, the base configuration is detector (Configuration), operating mode (MODE
=ACCUM), and filter. Chapter 5 presents detailed information about each ACS imaging mode.
Special Uses
We refer you to Chapter 6 if you are interested in any of the following special uses of ACS: slitless spectroscopy, polarimetry, and coronagraphy.
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