| | AAOmega File Format (or, which spectrum is which object?) |
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File Extensions |
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< | The table below gives a summary of the 2dfdr output file content, for either an individual reduced frame (....red.fits files) or a combined reduced frame (combined_frames.fits file). The file is a standard Multi-Extension FITS file (FITS MEF). See the FITS definition . |
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> | This table gives a summary of the 2dfdr output file content, for either an individual reduced frame (....red.fits files) or a combined reduced frame (combined_frames.fits files). The file is a standard Multi-Extension FITS file (FITS MEF). The extensions can be accessed in a number of ways given below. |
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| Extension |
IRAF format |
Contents |
| Primary |
.fits[0] |
The primary extension in the FITS file is a WxN image where W is the number of pixels in each spectrum, and N is the number of spectra represented. This is 400 for AAOmega data, 392 science fibres and 8 guide fibres. Unused science fibres and Sky spectra, are included in the output file along with the guide fibres spectra, even though the spectra contain no information, as this simplifies book keeping, and is a small disc space overhead. In the case where multiple sets of AAOmega datasets, which contained a subset of common objects, have been combined, the format is a little more complex, and is explained separately below. |
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| Variance |
.fits[1] |
The variance extension is also a WxN array. Each member contains the variance for the corresponding element in the primary extension. |
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| Variance |
.fits[1] |
The variance extension is also a WxN array identical in size to the primary extension. Each member contains the variance for the corresponding element in the primary extension. |
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| Fibre Table |
.fits[2] |
FITS binary table, with N rows, one for each fibre. Each row contains information for the fibre such as object name, position, etc. Full details are given below. |
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| Other Extensions |
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The files contain several other extensions which are generally only useful with in depth analysis of the data. They are not necessarily in order and are accessed by name. They are described here. |
The extensions can be accessed in a number of ways given below. |
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| Other Extensions |
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The files contain several other extensions which are generally only used when deeper analysis of the data is required. They are not necessarily in order and are accessed by name. They are described here. |
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The files output by 2dfdr also include data at intermediate processing steps. They are not normally used by scientist. They are described here. |
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