.help photpars May00 noao.digiphot.daophot
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NAME
photpars -- edit the photometry parameters
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USAGE
photpars
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PARAMETERS
.ls weighting = "constant"
The type of weighting. The weighting is ignored by the PHOT task. The options
are:
.ls constant
Uniform weights of 1 for each pixel are used.
.le
.ls cone
A conical weighting function of full width half maximum \fIfwhmpsf\fR as
defined in the DATAPARS parameter set is used.
.le
.ls gauss
A Gaussian weighting function of full width half maximum \fIfwhmpsf\fR as
defined in the DATAPARS parameter set is used.
.le
.le
.ls apertures = "3" (scale units)
A list of aperture radii in units of the  scale parameter or the name of the
file containing the list of apertures. List elements may be separated by
whitespace or commas. A ranges syntax of the form ap1:apN:apstep is also
supported. 
.le
.ls zmag = 25.00
The zero point offset for the magnitude scale. 
.le
.ls mkapert = no
Mark the photometry apertures on the displayed image?
.le

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DESCRIPTION

The integral of the flux within the circular apertures specified by
\fIapertures\fR is computed by summing pixels in the aperture with
the specified weighting function \fIweighting\fR. The fraction of each pixel
lying within the aperture is computed by an approximation and all the
approximations are summed.  The zero point of the magnitude
scale is determined by \fIzmag\fR.

\fRApertures\fR is specified in units of the image scale. If \fIscale\fR
is specified in units of the half-width at half-maximum of the point
spread function the aperture per pixel  a single value of apertures
will work well on images with differing psfs.


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EXAMPLES

1. List the PHOTPARS parameters.

.nf
    da> lpar photpars
.fi

2. Edit the PHOTPARS parameters.

.nf
    da> photpars
.fi

3. Edit the PHOTPARS parameters from with the PHOT task.

.nf
    da> epar phot

	... edit a few phot parameters

	... move to the photpars parameter and type :e

	... edit the photpars parameters and type :wq

	... finish editing the phot parameters and type :wq
.fi

4. Save the current PHOTPARS parameter set in a text file photnite1.par.
   This can also be done from inside a higher level task as in the above
   example.

.nf
    da> photpars

	... type ":w photnite1.par"  from within epar
.fi

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TIME REQUIREMENTS
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BUGS
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SEE ALSO
epar,datapars,centerpars,fitskypars,phot
.endhelp