Content-type: text/html Manpage of imblob

imblob

Section: User Commands (1)
Index Return to Main Contents
 

NAME

imblob - Fit 2-D gaussian in an image or cube  

PERSON RESPONSIBLE

pjt  

CATEGORIES

map analysis  

DESCRIPTION

IMBLOB is a Miriad task which fits a 2D gaussian to a user specified region. Only intensities larger than a specified cutoff are fit.

The model fit is :

      G(x,y) = OFFSET +  AMP * exp(-(x-X0)**2/(2*A**2) +
                                   -(y-Y0)**2/(2*B**2))

where A>B, and the x,y coordinate system is rotated by PA degrees w.r.t. the NAXIS2 axis (astronomical convention) towards the positive NAXIS1 axis.

A and B are the SIGMA, such that

      FWHM = sqrt(8*ln2) * SIGMA = 2.355 * SIGMA
 

PARAMETERS

in
The input image dataset name. No default.
region
Region over which the gaussian is to be fitted. Full region specifications are supported.
cutoff
Cutoff below which pixels are excluded from the fit. All points included are weighted equally. Use a large enough negative number to include all points. Default: 0.0
ini
If need be, this parameter can be used to supply the fitting routine with initial conditions other than the ones it derived on its own. The order of the parameters is: FWHM1, FWHM2 (arcsec), PA (degrees), AMP, OFFSET, XCEN, YCEN (absolute pixel coordinates: 1..naxisN). Default uses the derived values.
fix
If you want to fix the center, enter two numbers XCEN, YCEN here. They must be in absolute pixel coordinates. Default: not used. Note: using this keyword overrides the XCEN, YCEN used in ini=

put will be for 2D gaussians: Channel nr, Velocity, Xcen, Ycen(ARCSEC-REL), Xcen, Ycen (PIXEL-abs), AMP, FWHM_major, FWHM_minor, PA (degrees),


 

Index

NAME
PERSON RESPONSIBLE
CATEGORIES
DESCRIPTION
PARAMETERS

This document was created by man2html, using the manual pages.
Time: 18:35:38 GMT, July 05, 2011