Working with FITS Format


FITS is a digital data format developed for storing and transporting astronomical data in form of images and tables. The acronym FITS stands for "Flexible Image Transport System", which was developed in the 1970's at Kitt Peak National Observatory and was standardized in 1981. It has been maintained by NASA for more than 2 decades. A FITS format file consists of one of more Header-Data Units, with each "HDU" consisting of an ASCII text "header" containing metadata, followed by a multi-dimensional array that may contain pixel data for an image, or table data in the form of ASCII text or binary data. The FITS header and data array adhere to a rigid structure defined in the standard. It is critical to note that FITS is a data format, not an image format, as it was originally designed to hold one HDU of image data. It was later extended to hold multiple HDUs which may also hold table data. Mira provides numerous tools for working directly with the header and data as listed below. Commands for working directly with FITS data are described below. Also see the FITS Format Overview.

FITS Format Overview

Defines and describes the FITS format and Mira's implementation.

FITS Keywords

Defines the standard FITS keywords and additional keywords used by Mira.

Open FITS File

Opens one or more FITS files, where each file may contain one or more HDUs.

Save FITS Extension File

Saves the Image Set from an Image Window to a FITS file containing 'IMAGE' type extensions.

FITS Image Orientation

Defines the coordinate orientation used by FITS format images.

Pixel Scale Sensitive FITS Keywords

Lists Keywords that are updated by commands that change the spatial scale of the image.

Editing the FITS Header

Describes the general procedure for editing or modifying the FITS header information.

FITS Header Editor

Displays the FITS header information and permits the information to be edited. The header is opened in an independent window, separate from the image window.

FITS Header Pane

Displays the FITS header information and permits the information to be edited. The header is opened in a docking pane owned by the image window.

View and Search FITS Header

Displays the FITS header and permits text searching, opening in Excel, and copying to a Text Editor window.

List FITS File Header

OBSOLETE. This has been replaced by the View and Search FITS Header command.

List COMMENT Keywords

Describes how comments are stored in the FITS image header.

List HISTORY Keywords

Describes how the image processing history is stored in the FITS image header.

List Statistics Keywords

Displays the keywords and values resulting from Statistics Measurements.

List WCS Keywords

Displays the keywords used for describing a World Coordinate System attached to the image.

Modify Keywords

Changes keyword values in the FITS image header.

Add Metadata

Changes (adds, replaces, and renames) keyword metadata when the image is opened or is saved to a FITS format file. This command configures the metadata changes but the changes are actually committed based on global settings in the General Properties (Ctrl+R) dialog.

Create Image Keyword List

Creates a table of keyword values in a collection of images.

Search Keyword Values

Creates a table of keyword values meeting numerical criteria in a collection of images.

MIRAPROC Keyword

Encodes calibration information into the image header. Mira uses this to prevent repeating the specific steps of calibration.

Related Topics

Contents

FITS Format Overview


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