# SkyEllipticalAperture¶

class photutils.aperture.SkyEllipticalAperture(positions, a, b, theta=<Quantity 0. deg>)[source]

An elliptical aperture defined in sky coordinates.

The aperture has a single fixed size/shape, but it can have multiple positions (see the positions input).

Parameters
positionsSkyCoord

The celestial coordinates of the aperture center(s). This can be either scalar coordinates or an array of coordinates.

ascalar Quantity

The semimajor axis of the ellipse, either in angular or pixel units.

bscalar Quantity

The semiminor axis of the ellipse, either in angular or pixel units.

thetascalar Quantity, optional

The position angle (in angular units) of the ellipse semimajor axis. For a right-handed world coordinate system, the position angle increases counterclockwise from North (PA=0). The default is 0 degrees.

Examples

>>> from astropy.coordinates import SkyCoord
>>> import astropy.units as u
>>> from photutils import SkyEllipticalAperture
>>> positions = SkyCoord(ra=[10., 20.], dec=[30., 40.], unit='deg')
>>> aper = SkyEllipticalAperture(positions, 1.0*u.arcsec, 0.5*u.arcsec)


Attributes Summary

 a Check that value is either an angular or a pixel scalar Quantity. b Check that value is either an angular or a pixel scalar Quantity. positions Check that value is a SkyCoord. theta Check that value is either an angular scalar Quantity.

Methods Summary

 to_pixel(wcs) Convert the aperture to an EllipticalAperture object defined in pixel coordinates.

Attributes Documentation

a

Check that value is either an angular or a pixel scalar Quantity.

b

Check that value is either an angular or a pixel scalar Quantity.

positions

Check that value is a SkyCoord.

theta

Check that value is either an angular scalar Quantity.

Methods Documentation

to_pixel(wcs)[source]

Convert the aperture to an EllipticalAperture object defined in pixel coordinates.

Parameters
wcsWCS object

A world coordinate system (WCS) transformation that supports the astropy shared interface for WCS (e.g., astropy.wcs.WCS, gwcs.wcs.WCS).

Returns
aperture

An EllipticalAperture object.