daofind#
- astropop.photometry.daofind(data, threshold, background, noise, fwhm, mask=None, sharp_limit=(0.2, 1.0), round_limit=(-1.0, 1.0), exclude_border=True, positions=None)#
Find sources using DAOfind algorithm.
- Parameters:
- data: array_like
2D array containing the image to extract the sources.
- threshold: `int` or `float`
Minumim number of standard deviations above the background level where the algorithm will start to consider the sources.
- background: `float` or `~numpy.ndarray`
Background level estimation. Can be a single global value, or a 2D array with by-pixel values.
- noise: `float` or `~numpy.ndarray`
RMS or any other noise estimation to use in the detection. Can be a single global value, or a 2D array with by-pixel values. Due to limitations of photutils, if a 2D array is provided, it will be converted to a scalar using the median.
- fwhm: `float`
Full width at half maximum: to be used in the convolve filter.
- sharp_limit: array_like or `None` (optional)
Low and high cutoff for the sharpness statistic.
None
will disable the sharpness filtering. Default: (0.2, 1.0)- round_limitarray_like or
None
(optional) Low and high cutoff for the roundness statistic.
None
will disable the roundness filtering. Default: (-1.0,1.0)- mask: array_like (optional)
Boolean mask where 1 pixels are masked out in the background calculation. Default:
None
- exclude_border: `bool` (optional)
If
True
, sources found within half the size of the convolution kernel from the image borders are excluded. Default:True
- positions: array_like (optional)
List of (x, y) positions where to look for sources. If provided, the source finding step will be ignored and the centroids will be refined and filtered. Default:
None
- Returns:
- sources:
astropy.table.Table
Table with the sources found. The table will contain the following columns: -
id
: source ID -x
,y
: x and y coordinates of the source centroid -xcentroid
,ycentroid
: same asx
andy
-peak
: value of the source peak -flux
: integrated (background-subtracted) source flux within thesegment
fwhm
: FWHM of circular gaussian fit of the sourcesharpness
: The source DAOFIND sharpness statistic.roundness
: The source DAOFIND roundness statistic. Maximum betweeng_roundness
andr_roundness
.g_roundness
: The DAOFIND roundness statistic based on Gaussian marginal fit. Good for assymetries aligned with the x or y axis.s_roundness
: The DAOFIND roundness statistic based on symmetry of the source. Good for assymetries aligned with the diagonal.sigma_x
,sigma_y
: standard deviation of the source elipsoid along x and ytheta
: rotation angle of the source elipsoid (degrees) from the positive x axisfwhm
: FWHM of circular gaussian fit of the sourceeccentricity
: The eccentricity of the 2D Gaussian function that has the same second-order moments as the source.elongation
: The ratio of the lengths of the semimajor and semiminor axes.ellipticity
: 1.0 minus the elongation.cxx
,cyy
,cxy
: SourceExtractor ellipse parameters. See [SourceExtractor docs]_area
: area of the segment, in pixels
- sources: