NAME

phot - aperture photometry of stars in a CCD frame

SYNOPSIS

phot fits_file [aper=] [adu] [mzp=] [sky=] | [[skyinner=] [skyouter=]]

DESCRIPTION

phot uses positions of star centroids which have already been found, either by the stars routine or by hand (but which must then be put in the same format as the output of the stars command), and adds up all the counts within some specified radius (or several) of the centroid. Pixels lying partially inside a circular aperture of the specfied radius are included with a weight equal to that fraction of their area inside the aperture. A value for the sky background at that position is found by taking the modal (most frequently-occurring) value in an annulus centered on the star, and the sky is subtracted from the (star+sky) counts, leaving only the star. The brightness of the star is then converted into magnitudes - with an arbitrary zero scale above the local sky background and printed out.

If any of the apertures exceeds the image space the flag value (see output below) is set to an non zero value.

OPTIONS

adu- prints out total counts and not magnitude.

mzp= sets the magnitude zero point.

sky= overrides the sky local determined value.

aper= specifies the radius of a star aperture in pixels.

skyinner= specifies the inner radius of the sky aperture in pixels.

skyouter= specifies the outer radius of the sky aperture in pixels.

OUTPUT

The program prints a list to the standard output, where the fields have the following meanings:

XVista index