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

# astscript-zeropoint(1)

Estimate zero point of an image

## NAME

astscript-zeropoint - Estimate zero point of an image

## SYNOPSIS

**astscript-zeropoint** \[*OPTIONS*\] *image.fits*

## DESCRIPTION

Calculate the Zeropoint of the image based on a reference images or catalog.

### astscript-zeropoint options:

-

  Input(s):

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

  HDU/Extension name or number of input.

- **-S**, **--starcat**=*STR*

  Catalog with positions for aperture photomery.

- **--starcathdu**=*STR*/INT

  HDU of table in '--starcat'.

- **--starcatra**=*STR*/INT

  Column in '--starcat' that contains RA.

- **--starcatdec**=*STR*/INT

  Column in '--starcat' that contains DEC.

- **--mksrc**=*STR*

  Makefile (for developers when debugging).

-

  Output:

- **-o**, **--output**

  Output file name.

- **-t**, **--tmpdir**

  Directory to keep temporary files.

- **-k**, **--keeptmp**

  Keep temporal/auxiliar files.

- **-K**, **--keepzpap**

  Keep each aperture's zp in a different HDU.

-

  General settings

- **-a**, **--aperarcsec**=*FLT\[*,FLT\]

  Aperture radius (in arc-seconds) for photometry.

**-M**, **--magnituderange**=*FLT*,FLT Range of the magnitude to be considered.

-

  Reference catalog mode

- **-c**, **--refcat**=*STR*

  Reference catalog file name.

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

  Reference catalog HDU name of number.

- **-r**, **--refcatra**=*STR*

  Reference catalog Right Ascension (R.A.) column.

- **-d**, **--refcatdec**=*STR*

  Reference catalog Declination (Dec) column.

- **-m**, **--refcatmag**=*STR*

  Reference catalog Magnitude column.

- **-s**, **--matchradius**=*FLT*

  Radius (arcsec) to match stars and ref. catalog.

-

  Reference image mode

- **-R**, **--refimgs**=*STR\[*,STR\]

  Reference image name(s) with known zeropoint.

- **-H**, **--refimgshdu**=*STR*/INT

  Reference image HDU name(s) or number (s).

- **-z**, **--refimgszp**=*FLT\[*,FLT\]

  Zero point(s) of the reference image(s).

-

  Operating mode:

- **-h**, **--help**

  Print this help.

- **--cite**

  BibTeX citation for this program.

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

  Don't print any extra information in stdout.

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

  Print program version.

- **-N**, **--numthreads**=*INT*

  Number of threads; maximum if not given.

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

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

## REPORTING BUGS

Report bugs to bug-gnuastro@gnu.org

## COPYRIGHT

Copyright © 2022-2024 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 Sepideh Eskandarlou et al.

## SEE ALSO

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

-

  **info astscript-zeropoint**

should give you access to the complete manual.