Reference/APIΒΆ
Background estimation & source detection
sep.Background(data[, mask, maskthresh, bw, ...]) |
Representation of spatially variable image background and noise. |
sep.extract(data, thresh[, err, mask, ...]) |
Extract sources from an image. |
Aperture photometry
sep.sum_circle(data, x, y, r[, err, var, ...]) |
Sum data in circular aperture(s). |
sep.sum_circann(data, x, y, rin, rout[, ...]) |
Sum data in circular annular aperture(s). |
sep.sum_ellipse(data, x, y, a, b, theta, r) |
Sum data in elliptical aperture(s). |
sep.sum_ellipann(data, x, y, a, b, theta, ...) |
Sum data in elliptical annular aperture(s). |
Aperture utilities
sep.kron_radius(data, x, y, a, b, theta, r) |
Calculate Kron “radius” within an ellipse. |
sep.flux_radius(data, x, y, rmax, frac[, ...]) |
Return radius of a circle enclosing requested fraction of total flux. |
sep.winpos(data, xinit, yinit, sig[, mask, ...]) |
Calculate more accurate object centroids using ‘windowed’ algorithm. |
sep.mask_ellipse(arr, x, y, a, b, theta[, r]) |
Mask ellipse(s) in an array. |
sep.ellipse_axes(cxx, cyy, cxy) |
Convert from coefficient ellipse representation to ellipse axes and angle. |
sep.ellipse_coeffs(a, b, theta) |
Convert from ellipse axes and angle to coefficient representation. |
Low-level utilities
sep.get_extract_pixstack() |
Get the size in pixels of the internal pixel buffer used in extract(). |
sep.set_extract_pixstack(size) |
Set the size in pixels of the internal pixel buffer used in extract(). |
Flags
| Flag | Description |
|---|---|
sep.OBJ_MERGED |
object is result of deblending |
sep.OBJ_TRUNC |
object is truncated at image boundary |
sep.OBJ_SINGU |
x, y fully correlated in object |
sep.APER_TRUNC |
aperture truncated at image boundary |
sep.APER_HASMASKED |
aperture contains one or more masked pixels |
sep.APER_ALLMASKED |
aperture contains only masked pixels |
sep.APER_NONPOSITIVE |
aperture sum is negative in kron_radius |
To see if a given flag is set in flags:
is_merged = (flags & sep.OBJ_MERGED) != 0
Note
The coordinate convention in SEP is that (0, 0) corresponds to the center of the first element of the data array. This agrees with the 0-based indexing in Python and C. However, note that this differs from the FITS convention where the center of the first element is at coordinates (1, 1). As Source Extractor deals with FITS files, its outputs follow the FITS convention. Thus, the coordinates from SEP will be offset from Source Extractor coordinates by -1 in x and y.