---
name: "astfits"
section: "1"
platform: "linux"
package: "gnuastro"
version: "0.23-2+b3"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/astfits"
---

# astfits(1)

view and manipulate FITS headers

## NAME

Fits - view and manipulate FITS headers

## SYNOPSIS

**astfits** \[*OPTION*...\] *ASTRdata*

## DESCRIPTION

Fits is part of GNU Astronomy Utilities 0.23. Fits allows you to view and manipulate (add, delete, or modify) FITS extensions (or HDUs) and FITS header keywords within one extension.

For more information, please run any of the following commands. In particular the second contains a very comprehensive explanation of Fits's invocation: expected input(s), output(s), and a full description of all the options.

- All options and their values:

  $ astfits **-P**

- Inputs/Outputs and options:

  $ info astfits

- Full section in manual/book:

  $ info Fits

- Full Gnuastro manual/book:

  $ info gnuastro

If you couldn't find your answer in the manual, you can get direct help from experienced Gnuastro users and developers. For more information, please run:

-

  `$ info help-gnuastro`

Fits options:

-

  Input:

- **--arguments**=*STR*

  Plain-text file with command-line arguments.

- **-h**, **--hdu**=*STR*/INT

  Extension name or number of input data.

-

  Output:

- **-K**, **--keepinputdir**

  Keep input directory for automatic output.

- **--outfitsnocommit**

  No Git commit in 0-th HDU of output FITS.

- **--outfitsnoconfig**

  No metadata in 0-th HDU of output FITS.

- **--outfitsnodate**

  No 'DATE' in 0-th HDU of output FITS.

- **--outfitsnoversions**

  No versions in 0-th HDU of output FITS.

- **--outhdu**=*STR*

  HDU/extension in output for **--copykeys**.

- **-o**, **--output**=*STR*

  Output file name (not for keywords).

- **-O**, **--colinfoinstdout**

  Column info/metadata when printing to stdout.

- **--tableformat**=*STR*

  Table fmt: 'fits-ascii', 'fits-binary', 'txt'.

- **-T**, **--type**=*STR*

  Type of output: e.g., int16, float32, etc...

-

  HDU (extension) information:

- **--datasum**

  Calculate HDU's datasum and print in stdout.

- **--datasum-encoded**

  16 character string encoding of '--datasum'.

- **--hasimagehdu**

  File has at least one image HDU.

- **--hastablehdu**

  File has at least one table HDU.

- **--listallhdus**

  List all HDUs within the file.

- **--listimagehdus**

  List all image HDUs within the file.

- **--listtablehdus**

  List all table HDUs within the file.

- **-n**, **--numhdus**

  Print number of HDUs in the given FITS file.

- **--pixelareaarcsec2**

  Pixel area in arc-seconds squared.

- **--pixelscale**

  Return the pixel-scale of the HDU's WCS.

- **--skycoverage**

  Image coverage in the WCS coordinates.

-

  HDU (extension) manipulation:

- **-C**, **--copy**=*STR*/INT

  Copy extension to output file.

- **-k**, **--cut**=*STR*/INT

  Copy extension to output and remove from input.

- **--primaryimghdu**

  Copy/cut image HDUs to primary/zero-th HDU.

- **-R**, **--remove**=*STR*/INT

  Remove extension from input file.

-

  Keywords (in one HDU):

- **-a**, **--asis**=*STR*

  Write value as-is (may corrupt FITS file).

- **--copykeys**=*INT*:INT/STR,STR

  Range/Names of keywords to copy in output.

- **-c**, **--comment**=*STR*

  Add COMMENT keyword, any length is ok.

- **-d**, **--delete**=*STR*

  Delete a keyword from the header.

- **-H**, **--history**=*STR*

  Add HISTORY keyword, any length is ok.

- **-l**, **--keyvalue**=*STR\[*,STR,...\]

  Only print the value of requested keyword(s).

- **--printkeynames**

  Print all keyword names.

- **-p**, **--printallkeys**

  Print all keywords in the selected HDU.

- **-r**, **--rename**=*STR*,STR

  Rename keyword, keeping value and comments.

- **-s**, **--datetosec**=*STR*

  FITS date to sec from 1970/01/01T00:00:00

- **-t**, **--date**

  Set the DATE keyword to the current time.

- **-u**, **--update**=*STR*,STR

  Update a keyword value or comments.

- **-v**, **--verify**

  Verify the CHECKSUM and DATASUM keywords.

- **--wcscoordsys**=*STR*

  Convert WCS coordinate system.

- **--wcsdistortion**=*STR*

  Convert WCS distortion to another type.

- **-w**, **--write**=*STR*

  Write a keyword (with value, comments and units).

-

  Meta-image creation:

- **--edgesampling**=*INT*

  Number of extra samplings in pixel sides.

- **--pixelareaonwcs**

  Image where pixels show their area in sky (WCS).

-

  Operating modes:

- \-?, **--help**

  give this help list

- **--checkconfig**

  List all config files and variables read.

- **--cite**

  BibTeX citation for this program.

- **--config**=*STR*

  Read configuration file STR immediately.

- **--config-prefix**=*STR*

  Custom prefix of option names config files.

- **--lastconfig**

  Do not parse any more configuration files.

- **--minmapsize**=*INT*

  Min. bytes to avoid RAM automatically.

- **--onlyversion**=*STR*

  Only run if the program version is STR.

- **-P**, **--printparams**

  Print parameter values to be used and abort.

- **--quietmmap**

  Don't print mmap'd file's name and size.

- **-q**, **--quiet**

  Only report errors, remain quiet about steps.

- **-Q**, **--quitonerror**

  Quit if there is an error on any action.

- **-S**, **--setdirconf**

  Set default values for this directory and abort.

- **--usage**

  give a short usage message

- **-U**, **--setusrconf**

  Set default values for this user and abort.

- **-V**, **--version**

  print program version

Mandatory or optional arguments to long options are also mandatory or optional for any corresponding short options.

GNU Astronomy Utilities home page: http://www.gnu.org/software/gnuastro/

## REPORTING BUGS

Report bugs to bug-gnuastro@gnu.org.

## COPYRIGHT

Copyright © 2015-2024 Free Software Foundation, Inc. License GPLv3+: GNU General public license version 3 or later.\
 This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

Written/developed by Mohammad Akhlaghi

## SEE ALSO

The full documentation for **Fits** is maintained as a Texinfo manual.  If the **info** and **Fits** programs are properly installed at your site, the command

-

  **info Fits**

should give you access to the complete manual.
