sep.sum_ellipse¶

sep.sum_ellipse(data, x, y, a, b, theta, r, err=None, var=None, mask=None, maskthresh=0.0, bkgann=None, gain=None, subpix=5)¶

Sum data in elliptical aperture(s).

Parameters:

data : ndarray

2-d array to be summed.

x, y : array_like

Center coordinates and radius (radii) of aperture(s). x corresponds to the second (“fast”) axis of the input array and y corresponds to the first (“slow”) axis. x, y = (0.0, 0.0) corresponds to the center of the first element of the array. These inputs obey numpy broadcasting rules.

a, b, theta : array_like

Ellipse parameters. These inputs, along with x, y, and r, obey numpy broadcasting rules. a is the semi-major axis, b is the semi-minor axis and theta is angle in radians between the positive x axis and the major axis. It must be in the range [-pi/2, pi/2]. It is also required that a >= b >= 0.0.

r : array_like, optional

Scaling factor for the semi-minor and semi-major axes. The actual ellipse used will have semi-major axis a * r and semi-minor axis b * r. Setting this parameter to a value other than 1.0 is exactly equivalent to scaling both a and b by the same value. Default is 1.0.

err, var : float or ndarray

Error or variance (specify at most one).

mask : ndarray, optional

Mask array. If supplied, a given pixel is masked if its value is greater than maskthresh.

maskthresh : float, optional

Threshold for a pixel to be masked. Default is 0.0.

bkgann : tuple, optional

Length 2 tuple giving the inner and outer radius of a “background annulus”. If supplied, the background is estimated by averaging unmasked pixels in this annulus. If supplied, the inner and outer radii obey numpy broadcasting rules, along with x, y, and ellipse parameters.

gain : float, optional

Conversion factor between data array units and poisson counts, used in calculating poisson noise in aperture sum. If None (default), do not add poisson noise.

subpix : int, optional

Subpixel sampling factor. Default is 5.

Returns:

sum : ndarray

The sum of the data array within the aperture.

sumerr : ndarray

Error on the sum.

flags : ndarray

Integer giving flags. (0 if no flags set.)