stella.adapter

Interface PinholeShift

All Known Implementing Classes:

AbstractPinholeModel, AbstractPinholeShift, AveragePinhole, CenterOfGravityShift, ModelDrift, ModelShift, QuadrantShift

public interface PinholeShift

Algorithms that can determine a relative shift of a stellar image on an imaging fiber must implement this interface. The image measured is registered onto the object with the #fiberView method, which immediately returns a pixel shift. Depending on the sophistication of the algorithm, the method getPinholePosition() may return a fixed value, or a position determined from the last registered image. Additionally, getFlux() and getFwhm() might be available. If the algorithm is not capable of calculating the total flux and the fwhm of the star on the image fiber, they should return zero on both methods.

Method Summary

Modifier and Type	Method and Description
Vector2D	getBackground(MImageHDU pinhole) This method retrieves an estimate of the background ADU level plus its ADU sigma.
double	getFlux() If the algorithm is capable of calculating the total flux of the star, meaning including also the flux that disappeared into the fiber, it should be returned here in ADUs.
double	getFwhm() If the algorithm is capable of calculating the total FWHM of the star as it would have been without the pinhole, it should return this value in pixel here.
Point2D	getPinholePosition() Depending on the implementation, this method may return a fixed pinhole position, predetermined in its properties, or an estimated/ updated pinhole position from the last image registered.
double	getSignalToNoise(MImageHDU pinhole) Estimates the signal-to-noise ratio in the fiber view image.
Point2D	initFiberView(MFits pinhole) An image retrieved from a fiber entrance unit is registered here.
Point2D	solveFiberView() Finally dolves for the pinhole shift.

Method Detail

initFiberView

Point2D initFiberView(MFits pinhole)

An image retrieved from a fiber entrance unit is registered here. The method immediately returns the pixel shift of the star on the fiber entrance in plain pixels as found in the image. Only after calling this method, the getFlux() and getFwhm() have any meaning.

Parameters:

pinhole - The image of the pinhole entrance

Returns:

The pixel shift from the pinhole center to the star in a first model.

solveFiberView

Point2D solveFiberView()

Finally dolves for the pinhole shift. Needs a call to initFiberView(MFits) before.

Returns:

The pixel shift from the pinhole center to the star in the fitted model

getBackground

Vector2D getBackground(MImageHDU pinhole)

This method retrieves an estimate of the background ADU level plus its ADU sigma. Normally, mean or median will be used, we are not doing high quality photometry here. This method should return an estimate of the background plus a sort of RMS, which might be the standard deviation of the background ADUs in the simpliest case.

Returns:

The background ADU in x and its ADU-sigma in y.

getSignalToNoise

double getSignalToNoise(MImageHDU pinhole)

Estimates the signal-to-noise ratio in the fiber view image.

getPinholePosition

Point2D getPinholePosition()

Depending on the implementation, this method may return a fixed pinhole position, predetermined in its properties, or an estimated/ updated pinhole position from the last image registered.

getFlux

double getFlux()

If the algorithm is capable of calculating the total flux of the star, meaning including also the flux that disappeared into the fiber, it should be returned here in ADUs. If the algorithm is not capable of doing that, it should return zero. Acts on the fits image used in the last initFiberView(fits.hdu.MFits).

getFwhm

double getFwhm()

If the algorithm is capable of calculating the total FWHM of the star as it would have been without the pinhole, it should return this value in pixel here. If the algorithm is not capable of doing that, it should return zero. Acts on the fits image used in the last initFiberView(fits.hdu.MFits).