astro.fits

Interface MSifting

All Known Implementing Classes:

MFitsStarFind

public interface MSifting

Describes the capability to analyze a fits-HDU and extracts stars out of it. All arithmetics return 16-bit HDUs. Succeeds Guiding.

Author:

wooz

Method Summary

Modifier and Type	Method and Description
float[]	gauss(MImageHDU reduced, double fwhm, double trunc) Prepares a reduced image for star detection by applying a truncated Gaussian filter to it.
List<StarDetection>	getDetectedStars(Rectangle readout, Dimension binning, MImageHDU reduced, float[] gauss, int datamin, int datamax, int searchbox, int frame, float[] xstripes, float[] ystripes) Detect stars in the images using the reduced (or raw) frame plus the gaussian-filtered one.If the detector is shutterless, consider also to look for horizontal or vertical stripes.
MImageHDU	reduce(MImageHDU raw, double exptime, MImageHDU bias, MImageHDU dark, double darktime, MImageHDU flat) Prepares a raw image HDU by applying bias reduction, dark and flat-field correction.
List<StarDetection>	removeSpurious(List<StarDetection> found) Removes probably spurious detections.
float[]	xstripes(MImageHDU reduced, double fwhm, double trunc) Prepares a reduced image for star detection by applying a truncated Gaussian filter parallel to the x-axis.
float[]	ystripes(MImageHDU reduced, double fwhm, double trunc) Prepares a reduced image for star detection by applying a truncated Gaussian filter parallel to the y-axis.

Method Detail

reduce

MImageHDU reduce(MImageHDU raw,
                 double exptime,
                 MImageHDU bias,
                 MImageHDU dark,
                 double darktime,
                 MImageHDU flat)
          throws BasicFitsException

Prepares a raw image HDU by applying bias reduction, dark and flat-field correction. The dark must be normalized to the nominal exposure time of 1 and bias-subtracted. Any of the bias/dark/flat can be null and of any bit-depth.

Parameters:

exptime - The exposure time in multiples of the dark nominal exposure time

Returns:

A 16-bit reduced ImageHDU

Throws:

BasicFitsException

gauss

float[] gauss(MImageHDU reduced,
              double fwhm,
              double trunc)
       throws BasicFitsException

Prepares a reduced image for star detection by applying a truncated Gaussian filter to it. This is similar to the DAO Starfinder algorithm.

Parameters:

reduced -

fwhm -

trunc -

Returns:

A 16-bit gauss-filtered image as a float array

Throws:

BasicFitsException

xstripes

float[] xstripes(MImageHDU reduced,
                 double fwhm,
                 double trunc)
          throws BasicFitsException

Prepares a reduced image for star detection by applying a truncated Gaussian filter parallel to the x-axis.

Parameters:

reduced -

fwhm -

trunc -

Returns:

A 16-bit gauss-filtered image.

Throws:

BasicFitsException

ystripes

float[] ystripes(MImageHDU reduced,
                 double fwhm,
                 double trunc)
          throws BasicFitsException

Prepares a reduced image for star detection by applying a truncated Gaussian filter parallel to the y-axis.

Parameters:

reduced -

fwhm -

trunc -

Returns:

A 16-bit gauss-filtered image.

Throws:

BasicFitsException

getDetectedStars

List<StarDetection> getDetectedStars(Rectangle readout,
                                     Dimension binning,
                                     MImageHDU reduced,
                                     float[] gauss,
                                     int datamin,
                                     int datamax,
                                     int searchbox,
                                     int frame,
                                     float[] xstripes,
                                     float[] ystripes)
                              throws BasicFitsException

Detect stars in the images using the reduced (or raw) frame plus the gaussian-filtered one.If the detector is shutterless, consider also to look for horizontal or vertical stripes.

Parameters:

reduced - The reduced image, only for photometry.

gauss - The convolved image for star center using datamin and max

datamin - Minimum ADU value to spike star detection

datamax - Maximum value for a star, can be 65535

searchbox - Half-radius of the search box.

frame - No stars this close to the edges searched. Must be >= searchbox.

stripes - If >0, also check for read-out stripes.

Returns:

A list of detected stars, with sharpness, elongation and streakiness.

Throws:

BasicFitsException

removeSpurious

List<StarDetection> removeSpurious(List<StarDetection> found)

Removes probably spurious detections. This may be linked to the sharpness and elongation of the stars detected. This method physically removes entries from the supplied list. All deleted entries are returned in a new list.

Parameters:

found - All detections (ADU above certain threshold in filtered image).

Returns:

The list of detections removed from the original list.