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ACS Data Handbook > Chapter 2: ACS Data Structure > 2.4 Headers and Keywords

2.4
ACS image headers for WFC, HRC, HRC-ACQ, and SBC observations have very similar formats. However, MAMA (SBC) headers require a slightly modified structure from the CCD format, and HRC-ACQ headers require several unique keywords.
ACS header keywords can be viewed in several ways. The example below shows how these tasks are used to get the values for group (or extension) keyword CRVAL1.
Python INPUT:
Python OUTPUT: 5.952775438936009
 
ACS image header keywords are described in Tables 2.6 and 2.7. When printing the header, note that the keywords are grouped together by type, for example, "Target Information," "Science Instrument Configuration," "Calibration Switches," and "Calibration Reference files." There are also convenience functions for querying header keywords. For more information, see the Astropy documentation.
Keywords in the image's primary header (FITS extension 0) contain parameter values that are common to the entire image dataset, and are given in Table 2.6.
Extension or group header keywords (FITS extensions > 0), as shown in Table 2.7, contain parameter values that are specific to the image group (however, many primary header keyword values are also accessible when querying an image group header).
Table 2.6: Some keywords are no longer in use, but are included for users who may have older data.
Table 2.6: ACS Primary Header Keywords (FITS extension 0) (continued)
Table 2.6: ACS Primary Header Keywords (FITS extension 0) (continued)
Table 2.6: ACS Primary Header Keywords (FITS extension 0) (continued)
Table 2.6: ACS Primary Header Keywords (FITS extension 0) (continued)
Table 2.6: ACS Primary Header Keywords (FITS extension 0) (continued)
Table 2.6: ACS Primary Header Keywords (FITS extension 0) (continued)
Table 2.6: ACS Primary Header Keywords (FITS extension 0) (continued)
Table 2.6: ACS Primary Header Keywords (FITS extension 0) (continued)
Table 2.6: ACS Primary Header Keywords (FITS extension 0) (continued)
Table 2.7:
Table 2.7: ACS Extension Header Keywords (SCI, ERR, and DQ FITS extensions) (continued)
Table 2.7: ACS Extension Header Keywords (SCI, ERR, and DQ FITS extensions) (continued)
Table 2.7: ACS Extension Header Keywords (SCI, ERR, and DQ FITS extensions) (continued)
Table 2.7: ACS Extension Header Keywords (SCI, ERR, and DQ FITS extensions) (continued)
Table 2.7: ACS Extension Header Keywords (SCI, ERR, and DQ FITS extensions) (continued)
Table 2.7: ACS Extension Header Keywords (SCI, ERR, and DQ FITS extensions) (continued)
 
 

ACS Data Handbook > Chapter 2: ACS Data Structure > 2.4 Headers and Keywords

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