aperture

add_aperture_photometry(target, apertures)

Flux measurement from the image above the background inside a circular aperture.

Parameters

• target (MeasurementImage object, or leaf MeasurementGroup object with a single image, or a list of either) – Target images on which to measure the aperture photometry. Leaf MeasurementGroup with a single image are accepted as a convenience.

• apertures (float, or list of float) – Diameter of the aperture. As different MeasurementImage may not be aligned, nor have equivalent pixel size, the aperture is interpreted as diameter in pixels of a circle on the detection image. A transformation will be applied for each frame, so the covered area is equivalent.

Returns

An Aperture object is an internal representation of a property on the measurement frame that contains the apertures. To actually get the measurements on the output catalog, you need to add explicitly them to the output.

Return type

list of Aperture objects

See also

add_output_column

Notes

This property will generate five columns with the prefix specified by add_output_column: - _flux and _flux_err, for the flux and its associated error - _mag and _mag_err, for the magnitude and its associated error - _flags, to mark, for instance, saturation, boundary conditions, etc.

For M apertures and N images, the cells on the output column will be an array of MxN fluxes.

Examples

>>> measurement_group = MeasurementGroup(load_fits_images(frames, psfs))
>>> all_apertures = []
>>> for img in measurement_group:
>>>     all_apertures.extend(add_aperture_photometry(img, [5, 10, 20]))
>>> add_output_column('aperture', all_apertures)