12.1 FITS File Formats

The various files associated with each image represent the stages of NEWSIPS processing starting with the raw image (RI) file and ending with the merged extracted image (MX) file containing fluxes, wavelengths and data quality ($\nu$) flags. The Final Archive FITS files produced for low-dispersion images include the following:

RILO

The RI stored as a FITS primary array. If a partial read was used to obtain the image, an image extension is included containing the original unshifted RI (i.e., all corrections for registration errors are included in the primary array).

LILO

The linearized (i.e., photometrically corrected) image (LI) stored as a primary array with the associated array of $\nu$ flags stored in a FITS image extension.

VDLO

The vector displacements (VD) file contains the vector displacements, which map raw space into resampled space, and the cross-correlation coefficients (XC), which describe the mapping from raw space to the appropriate level of the raw space Intensity Transfer Function (ITF). The VD are stored as a three-dimensional (3-D) primary array, and the XC are stored in a FITS binary table extension.

SILO

The resampled image (SI) stored as a primary array with the associated $\nu$ flags in an image extension.

MXLO

The MX stored in a binary table extension, with each row containing the data extracted from one aperture.

If the RILO contains spectra collected through both the large and small aperture, the VDLO, SILO, and MXLO will contain data from both apertures. This is a slight change from the IUESIPS processing in which separate files were created for each aperture.

 

In the case of a high-dispersion spectrum the following files are generated:

RIHI

The RI (no partial-read image extensions are applicable).

LIHI

The LI and associated $\nu$ flags.

VDHI

The VD and XC data.

SIHI

The SI stored as a primary array, with wavelengths and predicted and found line positions stored in a binary table extension. The associated $\nu$ and cosmic ray flags are contained in two image extensions.

MXHI

The MX stored in a binary table extension with each row of the table representing data for one spectral order.

Some images may be processed as both high- and low-dispersion images and, consequently, will have both sets of files in the archive. In these cases, two copies of the RI file will appear in the archives, due to the dispersion-dependent keywords assigned during processing. All low- and high-dispersion Final Archive file formats are summarized in Tables 12.1 and 12.2. File sizes and formats summarized as ``various'' in these tables are explicitly described in the subsequent sections of this chapter.

 

 

File ID Data Stored Size Format FITS Type

RILO Raw Image 768x768 8-bit primary array

$$^\ast$$ 768x768 8-bit image extension

LILO Linearized Image 768x768 I*2 primary array

Linearized Flag Image 768x768 I*2 image extension

SILO Resampled Image 640x80 I*2 primary array

Resampled Flag Image 640x80 I*2 image extension

VDLO Vector Displacements 768x768x2 R*4 primary array

Cross-correlation Parameters various various binary table extension

MXLO Extracted Spectra various various binary table extension

$$^\ast$$

 

 

File ID Data Stored Size Format FITS Type

RIHI Raw Image 768x768 8-bit primary array

LIHI Linearized Image 768x768 I*2 primary array

Linearized Flag Image 768x768 I*2 image extension

VDHI Vector Displacements 768x768x2 R*4 primary array

Cross-correlation Parameters various various binary table extension

SIHI Resampled Image 768x768 I*2 primary array

SIHI wavelengths and various various binary table extension predicted and found line positions

Resampled Flag Image 768x768 I*2 image extension

SIHI Cosmic Ray Image 768x768 8-bit image extension

MXHI Extracted Spectra various various binary table extension