FringeTask

class lsst.ip.isr.FringeTask(config: Config | None = None, *, name: str | None = None, parentTask: Task | None = None, log: logging.Logger | lsst.utils.logging.LsstLogAdapter | None = None)

Bases: Task

Task to remove fringes from a science exposure

We measure fringe amplitudes at random positions on the science exposure and at the same positions on the (potentially multiple) fringe frames and solve for the scales simultaneously.

Methods Summary

checkFilter(exposure)	Check whether we should fringe-subtract the science exposure.
generatePositions(exposure, rng)	Generate a random distribution of positions for measuring fringe amplitudes.
loadFringes(fringeExp[, expId, assembler])	Pack the fringe data into a Struct.
measureExposure(exposure, positions[, title])	Measure fringe amplitudes for an exposure
removePedestal(fringe)	Remove pedestal from fringe exposure.
run(exposure, fringes[, seed])	Remove fringes from the provided science exposure.
solve(science, fringes)	Solve for the scale factors with iterative clipping.
subtract(science, fringes, solution)	Subtract the fringes.

Methods Documentation

checkFilter(exposure)

Check whether we should fringe-subtract the science exposure.

Parameters

exposurelsst.afw.image.Exposure

Exposure to check the filter of.

Returns

needsFringebool

If True, then the exposure has a filter listed in the configuration, and should have the fringe applied.

generatePositions(exposure, rng)

Generate a random distribution of positions for measuring fringe amplitudes.

Parameters

exposurelsst.afw.image.Exposure

Exposure to measure the positions on.

rngnumpy.random.RandomState

Random number generator to use.

Returns

positionsnumpy.array

Two-dimensional array containing the positions to sample for fringe amplitudes.

loadFringes(fringeExp, expId=None, assembler=None)

Pack the fringe data into a Struct.

This method moves the struct parsing code into a butler generation agnostic handler.

Parameters

fringeExplsst.afw.exposure.Exposure

The exposure containing the fringe data.

expIdint, optional

Exposure id to be fringe corrected, used to set RNG seed.

assemblerlsst.ip.isr.AssembleCcdTask, optional

An instance of AssembleCcdTask (for assembling fringe frames).

Returns

fringeDatapipeBase.Struct

Struct containing fringe data:

fringes

Calibration fringe files containing master fringe frames. ( : lsst.afw.image.Exposure or list thereof)

seed

Seed for random number generation. (int, optional)

measureExposure(exposure, positions, title='Fringe')

Measure fringe amplitudes for an exposure

The fringe amplitudes are measured as the statistic within a square aperture. The statistic within a larger aperture are subtracted so as to remove the background.

Parameters

exposurelsst.afw.image.Exposure

Exposure to measure the positions on.

positionsnumpy.array

Two-dimensional array containing the positions to sample for fringe amplitudes.

titlestr, optional

Title used for debug out plots.

Returns

fringesnumpy.array

Array of measured exposure values at each of the positions supplied.

removePedestal(fringe)

Remove pedestal from fringe exposure.

Parameters

fringelsst.afw.image.Exposure

Fringe data to subtract the pedestal value from.

run(exposure, fringes, seed=None)

Remove fringes from the provided science exposure.

Primary method of FringeTask. Fringes are only subtracted if the science exposure has a filter listed in the configuration.

Parameters

exposurelsst.afw.image.Exposure

Science exposure from which to remove fringes.

fringeslsst.afw.image.Exposure or list thereof

Calibration fringe files containing master fringe frames.

seedint, optional

Seed for random number generation.

Returns

solutionnp.array

Fringe solution amplitudes for each input fringe frame.

rmsfloat

RMS error for the fit solution for this exposure.

solve(science, fringes)

Solve for the scale factors with iterative clipping.

Parameters

sciencenumpy.array

Array of measured science image values at each of the positions supplied.

fringesnumpy.array

Array of measured fringe values at each of the positions supplied.

Returns

solutionnp.array

Fringe solution amplitudes for each input fringe frame.

rmsfloat

RMS error for the fit solution for this exposure.

subtract(science, fringes, solution)

Subtract the fringes.

Parameters

sciencelsst.afw.image.Exposure

Science exposure from which to remove fringes.

fringeslsst.afw.image.Exposure or list thereof

Calibration fringe files containing master fringe frames.

solutionnp.array

Fringe solution amplitudes for each input fringe frame.

Raises

RuntimeError

Raised if the number of fringe frames does not match the number of measured amplitudes.