[AstroPy] Gaussian models fitter non-functional?

[Steve Crawford]

Hi Jeff--

The fitted model will not be in g_init (this remains unchanged), but in g.   If you take a look in g, you should be able to see the fitted results.

Cheers
Steve

----- Original Message -----
From: "Jeff Mangum" <jmangum at nrao.edu>
To: astropy at scipy.org
Sent: Friday, October 16, 2015 3:11:56 PM
Subject: [AstroPy] Gaussian models fitter non-functional?

Hello,

Long-time listener but first-time caller.  Have been trying to use the 
2D Gaussian fitting capabilities within astropy.models to fit a 2D 
Gaussian to an image (in FITS format).  Here is my script:

import numpy as np
import radio_beam
from astropy.modeling import models, fitting
from astropy import units as u
from astropy.io import fits
import astropy.coordinates as coord
import astropy.wcs as wcs
import matplotlib
import pylab as pl

# The following is the position of the peak in both J1 and J2, so use
# it as the starting guess
ra0 = '13h15m03.50s'
dec0 = '24d37m08.2s'

radeg = coord.Angle(ra0, unit=u.hour).degree
decdeg = coord.Angle(dec0, unit=u.degree)

# Now open the image
hdulist = fits.open('IC860CbandCarrayH2COJ1_moment0.fits')
#hdulist = fits.open('IC860KubandDarrayH2COJ2_moment0.fits')
w = wcs.WCS(hdulist[0].header, hdulist)

yy,xx = np.indices(hdulist[0].data.shape)

x0,y0 = w.wcs_world2pix(radeg, decdeg, 1)

# Now fit 2D gaussian
g_init = models.Gaussian2D(amplitude=1., x_mean=x0, y_mean=y0, 
x_stddev=1, y_stddev=1)
fit_g = fitting.LevMarLSQFitter()
g = fit_g(g_init, xx, yy, hdulist[0].data)


When I look at g_init (which is where I believe the fit results should 
be), I see that the fit has not moved from its initial settings.  It 
appears that the fitter just did not run.  With Adam Ginsburg's help I 
have a workaround using gaussfitter, but would certainly like to make 
this work with astropy.models.  Thanks!

-- Jeff
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