MUSE Pipeline Reference Manual
2.1.1
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Functions | |
cpl_table * | muse_find_stars (const cpl_image *aImage, double aHmin, double aFwhm, const double *aRoundLimits, const double *aSharpLimits) |
Find positive brightness perturbations (i.e stars) in an image. More... | |
This group provides a simple 2d image source detection based of the DAOFIND algorithm (Stetson P.B., 1987, PASP 99, 191).
This implementation of the DAOFIND algorithm is largely based on the C implementation of the IDL find routine which was developed by A. Pecontal to be used in the MUSE Instrument Control Software.
cpl_table* muse_find_stars | ( | const cpl_image * | aImage, |
double | aHmin, | ||
double | aFwhm, | ||
const double * | aRoundLimits, | ||
const double * | aSharpLimits | ||
) |
Find positive brightness perturbations (i.e stars) in an image.
aImage | 2D image to be searched for stars. |
aHmin | Minimum value above background for threshold detection |
aFwhm | FWHM (in pixels) to be used in the convolution filter |
aSharpLimits | 2 element vector giving low and high cutoff for the sharpness statistic. |
aRoundLimits | 2 element vector giving low and high cutoff for the roundness statistic. |
NULL
in case of an error.Find positive brightness perturbations (i.e stars) in an image and return the centroid position, (uncalibrated) flux and the shape parameters (roundness and sharpness).
For each detected star the measured properties are stored in one row of the results table. The measured coordinates, flux, sharpness and roundness are written to the table columns X
, Y
, Flux
, Sharpness
, and Roundness
, respectively.
The size of the input image aImage must be even along its x-axis. The minimum value above the background aHmin should, in general, be set to 3 or 4 sigma above background RMS. The input FWHM aFwhm must be larger than 0.5 pixels.
If NULL
is passed for aSharpLimits and/or aRoundLimits, the built-in defaults are used.
The default ranges for aSharpLimits and/or aRoundLimits are [0.2,1.0] and [-1.0,1.0] respectively. The limits of the sharpness statistic should only be changed if the stars have a significantly smaller or larger concentration than a Gaussian. Similarly, the limits of the roundness statistic should only be changed if the stars are significantly elongated.
Adapted from IDL implementation of the DAOPHOT FIND routine which does not allow for bad pixels and uses a slightly different centroid algorithm. Uses marginal Gaussian fits to find centroids.
set CPL_ERROR_NULL_INPUT, return NULL | a parameter is NULL |
set CPL_ERROR_ILLEGAL_INPUT, return NULL | a parameter is not a valid input |
set CPL_ERROR_INCOMPATIBLE_INPUT, return NULL | convolution of the input image with a Gaussian failed |
set CPL_ERROR_DATA_NOT_FOUND, return NULL | no candidate sources where found |
Definition at line 455 of file muse_findstars.c.
References muse_convolve_image(), muse_cplarray_erase_invalid(), muse_cplmatrix_extract_selected(), muse_cplmatrix_multiply_create(), and muse_cplmatrix_where().