FITS header

Keywords contained in the header of a FITS file can be displayed in Siril. To do this, simply click on Tool ‣ FITS Header. Another way of displaying the header is to use the command line dumpheader.

Since version 1.3.0, it is possible to modify the value of keywords supported by Siril, either with the update_key command, or via the graphical interface, in the appropriate window.


Siril does not allow you to modify the header of a sequence file on the fly.


There's a difference between what's displayed on the command line and what you see in graphics mode. In the latter mode, only keywords managed by Siril are displayed, whereas dumpheader displays all keywords present in the file. As a result, it's not always possible to update a value, with update_key, if Siril doesn't manage the keyword.

Only key values can be modified, not comments. In addition, the key must be unprotected. For easy recognition, protected keys are displayed in salmon color. Editing is very simple, just double-click on the key value. The first time selects the field, the second opens the edit mode. Pressing the Enter key validates the entry.


Please note that Siril does not check the validity of the value entered. It is up to the user to enter a valid value. An incorrect value may lead to undesirable behavior in Siril's keyword processing.

FITS Header

FITS Header dialog when editing the value of a keyword.

The window contains an option in the form of a button Copy Selection. It copies selected lines to the clipboard.

Siril command line

Dumps the FITS header of the loaded image in the console

Siril command line

update_key key value
Updates FITS keyword. The argument key must be an FITS keyword found in the header and managed by Siril. Please note that the validity of value is not checked. This verification is the responsibility of the user