function find

[This documentation is copied literally from IDL's astrolib]

Find positive brightness perturbations (i.e stars) in an image. Also returns centroids and shape parameters (roundness & sharpness). Adapted from 1986 STSDAS version of DAOPHOT.

Syntax
result = find(image, hmin, fwhm [, roundlim [, sharplim]] [, /silent])

Arguments

image:   2 dimensional image array for which one wishes to identify the stars present.

hmin:   Threshold intensity for a point source - should generally be 3 or 4 sigma above background.

fwhm:   FWHM to be used in the convolve filter.

sharplim:   2 element vector giving low and high cutoff for the sharpness statistic (Default: [0.2,1.0]). Change this default only if the stars have significantly larger or or smaller concentration than a Gaussian.

roundlim:   2 element vector giving low and high cutoff for the roundness statistic (Default: [-1.0,1.0]). Change this default only if the stars are significantly elongated.

Switches

silent:   Normally, FIND will write out each star that meets all selection criteria. If the SILENT keyword is set then this printout is suppressed.

Returns
The find function returns an array of size 5xnstars with the following entries:
x: vector containing x position of all stars identified by FIND
y: vector containing y position of all stars identified by FIND
flux: vector containing flux of identified stars as determined by a gaussian fit. Fluxes are NOT converted to magnitudes.
sharp: vector containing sharpness statistic for identified stars
round: vector containing roundness statistic for identified stars

Notes
The sharpness statistic compares the central pixel to the mean of the surrounding pixels. If this difference is greater than the originally estimated height of the Gaussian or less than 0.2 the height of the Gaussian (for the default values of SHARPLIM) then the star will be rejected.

image:	2 dimensional image array for which one wishes to identify the stars present.
hmin:	Threshold intensity for a point source - should generally be 3 or 4 sigma above background.
fwhm:	FWHM to be used in the convolve filter.
sharplim:	2 element vector giving low and high cutoff for the sharpness statistic (Default: [0.2,1.0]). Change this default only if the stars have significantly larger or or smaller concentration than a Gaussian.
roundlim:	2 element vector giving low and high cutoff for the roundness statistic (Default: [-1.0,1.0]). Change this default only if the stars are significantly elongated.