---
name: "imstar"
section: "1"
platform: "linux"
package: "wcstools"
version: "3.9.7-1.1+b1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/imstar"
---

# imstar(1)

Find stars in FITS and IRAF image files

## Name

imstar - Find stars in FITS and IRAF image files

## Synopsis

imstar  \[options\] \[FITS or IRAF filename\] or \[@file of image file names\]

## Description

## Options

- **\<hh:mm:ss\> \<dd:mm:ss\> \[J2000, B1950\]**

  Coordinates for center (or reference pixel if -x is used).

- **-a \<angle\>**

  Image rotation angle in degrees (default 0).  If multiple of 90, rotate image before search and set WCS angle to zero; if not, put in WCS.

- **-b**

  Output B1950 (FK4) coordinates (default=image equinox)

- **-d \<catalog name\>**

  Read this DAOFIND style catalog of X, Y, and magnitude instead of searching for stars in the image.  The format is simply white-space-separated numbers on a line, with # at the beginning of comment lines.

- **-e \<num\>**

  Number of pixels to ignore around image edge

- **-f**

  Write a simple ASCII catalog file instead of tab table or DAOFIND format (number RA DEC mag ... per line, with two lines of header info)

- **-h**

  Print heading, else do not

- **-i \<num\>**

  Minimum peak value for star in image (\<0=-sigma) Setting this to reject all but 10-15 stars is a good way to speed up the star-finding process.  If num is less than zero, the minimum peak is -num image pixel standard deviations.  Setting this number rejects faint stars early in the selection process for a significant saving in computing time.

- **-j**

  Output J2000 (FK5) coordinates (default=image equinox)

- **-k**

  Print each star as it is found for debugging

- **-l**

  Reflect the image left \<-\> right before rotating (-a) and searching for stars.

- **-m \<magnitude\>**

  Magnitude offset

- **-n**

  Number of brightest stars to print

- **-o**

  Output star list in DAOFIND format. The first three numbers on each line of the output file are X, Y, and magnitude, separated by one or more blanks or a tab.  Lines beginning with # are ignored.

- **-p \<num\>**

  Plate scale in arcsec per pixel (default 0)

- **-q \<c\|d\|o\|s\|x\|v\|+\>**

  Output region file shape for SAOimage (default o) Characters mean: c\>ross, d\>iamond, s\>quare, o\>circle, x=X, v\>ary with GSC type, +\>cross.

- **-r**

  Maximum radius for star in pixels

- **-s**

  Sort by RA instead of flux

- **-t**

  Output in Starbase tab table format

- **-v**

  Verbose listing of processing intermediate results

- **-w**

  Write output to a file in addition to standard out. If DAO format (-o), create the name by adding .dao to the image file name. If Starbase format (-t), create the name by adding .tab to the image file name. If ASCII format (-f), create the name by adding .stars to the image file name.

- **-x \<X\> \<Y\>**

  X and Y coordinates of reference pixel (if not in header or image center)

- **-z**

  Use AIPS classic projection code (for "-SIN", "-TAN", "-ARC", "-NCP", "-GLS", "-MER", "-AIT" and "-STG" only) instead of WCSLIB proposed standard projection code.

## Web Page

http://tdc-www.harvard.edu/software/wcstools/imstar/

## Author

Jessica Mink, SAO (jmink@cfa.harvard.edu)