Test showing that non fixed scale results different photometric flux depending on the number of positions

test_SkyCircularAperture.py

from astropy.io import fits
from astropy.wcs import WCS
import numpy as np
import astropy.units as u

from photutils import SkyCircularAperture, aperture_photometry
from photutils.extern.wcs_utils import pixel_to_skycoord

image_shape = (100, 200)
header = WCS({'CTYPE1': 'RA---TAN',
              'CTYPE2': 'DEC--TAN',
              'CRPIX1': int(image_shape[1] / 2),
              'CRPIX2': int(image_shape[0] / 2)}, ).to_header()

hdu = fits.ImageHDU(np.ones(image_shape), header=header)

pos_p = u.Quantity(([150., 20., 150., 150.],
                    [65., 20., 6., 35.]), unit=u.pixel)
pos_p_s = u.Quantity(([150., ], [65., ]), unit=u.pixel)

pos = pixel_to_skycoord(pos_p[0], pos_p[1], WCS(hdu.header))
pos_s = pixel_to_skycoord(pos_p_s[0], pos_p_s[1], WCS(hdu.header))

photometry_skycoord_circ = aperture_photometry(
    hdu, SkyCircularAperture(pos, 3 * u.deg))
photometry_skycoord_circ_s = aperture_photometry(
    hdu, SkyCircularAperture(pos_s, 3 * u.deg))

print photometry_skycoord_circ
print photometry_skycoord_circ_s