Photoutils/Aperture photometry is triggerring "Nonetype" error

Question

I am performing aperture photometry over thousands of images and have this piece of code in my module.

b_aperture = SkyCircularAperture(b_position, r= r*u.arcsec)
b_annulus_aperture = SkyCircularAnnulus(b_position, r_in= r_in*  u.arcsec, r_out= r_out* u.arcsec) 
b_ap_pix = b_aperture.to_pixel(w_n)
b_ap_pix_mask= b_ap_pix.to_mask(method='exact')[0]
c_img_data = b_ap_pix_mask.apply(masked_img_aper)

This works fine on most of the images but in some of the images it triggers following error;

> <ipython-input-41-d3d69b9fd615> in <module>()
 51         b_ap_pix = b_aperture.to_pixel(w_n)
 52         b_ap_pix_mask= b_ap_pix.to_mask(method='exact')[0]   
 53         c_img_data = b_ap_pix_mask.apply(masked_img_aper)
 55         b_phot_table = aperture_photometry(masked_img_aper, b_aperture, method ='exact', wcs =w_n )
 /Users/aprakash/Library/Enthought/Canopy/edm/envs/User/lib/python3.5/site-packages/photutils/aperture/core.py in apply(self, data, fill_value)
719         """ 
721         return self.cutout(data, fill_value=fill_value) * self.data
722 
TypeError: unsupported operand type(s) for *: 'NoneType' and 'float'}

This error usually happens when the variables are not defined but I have checked that the variable here "masked_img_aper" is defined and looks like a normal image. The mask "b_ap_pix_mask" also look normal like other masks on previous images. So, I am not sure what's going on and how to fix this. My code runs in a loop over thousands of images and this is only happening for a few images which breaks down the code. I would like to circumvent this issue (possibly by using "if" statement) or fix it.

I tried following but it didn't work;

if (isinstance(np.array(b_ap_pix_mask.apply(masked_img_aper)), NoneType) == False;

Any ideas would be appreciated. Best, Abhi

Answer 1

It looks like this is a bug that was fixed in the current version under development: https://github.com/astropy/photutils/pull/646

Answer 2

Okay, I have found a way to circumvent this issue using following;

try:
    c_img_data = b_ap_pix_mask.multiply(masked_img_aper)
except:
    print('Error calling b_ap_pix_mask.multiply(), ignoring')
    pass

This will just skip the image in the loop. Since, I am working with thousands of images, leaving out a few won't make much of a difference.