SkyEllipticalAnnulus¶

class photutils.aperture.SkyEllipticalAnnulus(positions, a_in, a_out, b_out, b_in=None, theta=<Quantity 0. deg>)[source]¶

Bases: SkyAperture

An elliptical annulus 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.
a_inscalar Quantity: The inner semimajor axis in angular units.
a_outscalar Quantity: The outer semimajor axis in angular units.
b_outscalar Quantity: The outer semiminor axis in angular units.
b_inNone or scalar Quantity: The inner semiminor axis in angular units. If None, then the inner semiminor axis is calculated as:

\[b_{in} = b_{out} \left(\frac{a_{in}}{a_{out}}\right)\]
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).

Examples

>>> from astropy.coordinates import SkyCoord
>>> import astropy.units as u
>>> from photutils.aperture import SkyEllipticalAnnulus
>>> positions = SkyCoord(ra=[10.0, 20.0], dec=[30.0, 40.0], unit='deg')
>>> aper = SkyEllipticalAnnulus(positions, 0.5*u.arcsec, 2.0*u.arcsec,
...                             1.0*u.arcsec)

Attributes Summary

`a_in`	The inner semimajor axis in angular units.
`a_out`	The outer semimajor axis in angular units.
`b_in`	The inner semiminor axis in angular units.
`b_out`	The outer semiminor axis in angular units.
`isscalar`	Whether the instance is scalar (i.e., a single position).
`positions`	The center position(s) in sky coordinates.
`shape`	The shape of the instance.
`theta`	The position angle in angular units of the ellipse semimajor axis.

Methods Summary

`copy`()	Make an independent (deep) copy.
`to_pixel`(wcs)	Convert the aperture to an `EllipticalAnnulus` object defined in pixel coordinates.

Attributes Documentation

a_in¶: The inner semimajor axis in angular units.

a_out¶: The outer semimajor axis in angular units.

b_in¶: The inner semiminor axis in angular units.

b_out¶: The outer semiminor axis in angular units.

isscalar¶: Whether the instance is scalar (i.e., a single position).

positions¶: The center position(s) in sky coordinates.

shape¶: The shape of the instance.

theta¶: The position angle in angular units of the ellipse semimajor axis.

Methods Documentation

copy()¶: Make an independent (deep) copy.

to_pixel(wcs)[source]¶

Convert the aperture to an EllipticalAnnulus 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:

apertureEllipticalAnnulus object: An EllipticalAnnulus object.

Navigation

SkyEllipticalAnnulus¶