ComputePixelScale¶

class lsst.pipe.tasks.functors.ComputePixelScale(colCD_1_1, colCD_1_2, colCD_2_1, colCD_2_2, **kwargs)¶

Bases: LocalWcs

Compute the local pixel scale from the stored CDMatrix.

Attributes Summary

`columns`	Columns required to perform calculation.
`name`
`noDup`	Do not explode by band if used on object table.
`shortname`	Short name of functor (suitable for column name/dict key).

Methods Summary

`__call__`(data[, dropna])	Call self as a function.
`computeDeltaRaDec`(x, y, cd11, cd12, cd21, cd22)	Compute the dRA, dDec from dx, dy.
`computePositionAngle`(ra1, dec1, ra2, dec2)	Compute position angle (E of N) from (ra1, dec1) to (ra2, dec2).
`computeSkySeparation`(ra1, dec1, ra2, dec2)	Compute the local pixel scale conversion.
`difference`(data1, data2, **kwargs)	Computes difference between functor called on two different DataFrame/Handle objects.
`fail`(df)
`getPositionAngleFromDetectorAngle`(theta, ...)	Compute position angle (E of N) from detector angle (+y of +x).
`getSkySeparationFromPixel`(x1, y1, x2, y2, ...)	Compute the distance on the sphere from x2, y1 to x1, y1.
`multilevelColumns`(data[, columnIndex, ...])	Returns columns needed by functor from multilevel dataset.
`pixelScaleArcseconds`(cd11, cd12, cd21, cd22)	Compute the local pixel to scale conversion in arcseconds.

Attributes Documentation

columns¶

name = 'PixelScale'¶

noDup¶: Do not explode by band if used on object table.

shortname¶: Short name of functor (suitable for column name/dict key).

Methods Documentation

__call__(data, dropna=False)¶: Call self as a function.

computeDeltaRaDec(x, y, cd11, cd12, cd21, cd22)¶

Compute the dRA, dDec from dx, dy.

Parameters:

xSeries: X pixel coordinate.
ySeries: Y pixel coordinate.
cd11Series: [1, 1] element of the local Wcs affine transform.
cd12Series: [1, 2] element of the local Wcs affine transform.
cd21Series: [2, 1] element of the local Wcs affine transform.
cd22Series: [2, 2] element of the local Wcs affine transform.

Returns:

raDecTupletuple: RA and Dec conversion of x and y given the local Wcs. Returned units are in radians.

Notes

If x and y are with respect to the CRVAL1, CRVAL2 then this will return the RA, Dec for that WCS.

computePositionAngle(ra1, dec1, ra2, dec2)¶

Compute position angle (E of N) from (ra1, dec1) to (ra2, dec2).

Parameters:

ra1iterable [float]: RA of the first coordinate [radian].
dec1iterable [float]: Dec of the first coordinate [radian].
ra2iterable [float]: RA of the second coordinate [radian].
dec2iterable [float]: Dec of the second coordinate [radian].

Returns:

Position Angle: Series: radians E of N

Notes

(ra1, dec1) -> (ra2, dec2) is interpreted as the shorter way around the sphere

For a separation of 0.0001 rad, the position angle is good to 0.0009 rad all over the sphere.

computeSkySeparation(ra1, dec1, ra2, dec2)¶

Compute the local pixel scale conversion.

Parameters:

ra1Series: Ra of the first coordinate in radians.
dec1Series: Dec of the first coordinate in radians.
ra2Series: Ra of the second coordinate in radians.
dec2Series: Dec of the second coordinate in radians.

Returns:

distSeries: Distance on the sphere in radians.

difference(data1, data2, **kwargs)¶: Computes difference between functor called on two different DataFrame/Handle objects.

fail(df)¶

getPositionAngleFromDetectorAngle(theta, cd11, cd12, cd21, cd22)¶

Compute position angle (E of N) from detector angle (+y of +x).

Parameters:

thetafloat: detector angle [radian]
cd11float: [1, 1] element of the local Wcs affine transform.
cd12float: [1, 2] element of the local Wcs affine transform.
cd21float: [2, 1] element of the local Wcs affine transform.
cd22float: [2, 2] element of the local Wcs affine transform.

Returns:

Position Angle: Series: Degrees E of N.

getSkySeparationFromPixel(x1, y1, x2, y2, cd11, cd12, cd21, cd22)¶

Compute the distance on the sphere from x2, y1 to x1, y1.

Parameters:

x1Series: X pixel coordinate.
y1Series: Y pixel coordinate.
x2Series: X pixel coordinate.
y2Series: Y pixel coordinate.
cd11Series: [1, 1] element of the local Wcs affine transform.
cd12Series: [1, 2] element of the local Wcs affine transform.
cd21Series: [2, 1] element of the local Wcs affine transform.
cd22Series: [2, 2] element of the local Wcs affine transform.

Returns:

DistanceSeries: Arcseconds per pixel at the location of the local WC.

multilevelColumns(data, columnIndex=None, returnTuple=False)¶

Returns columns needed by functor from multilevel dataset.

To access tables with multilevel column structure, the DeferredDatasetHandle or InMemoryDatasetHandle needs to be passed either a list of tuples or a dictionary.

Parameters:

datavarious: The data as either DeferredDatasetHandle, or InMemoryDatasetHandle.
columnIndex (optional): pandas `~pandas.Index` object: Either passed or read in from DeferredDatasetHandle.
`returnTuple`bool: If true, then return a list of tuples rather than the column dictionary specification. This is set to True by CompositeFunctor in order to be able to combine columns from the various component functors.

pixelScaleArcseconds(cd11, cd12, cd21, cd22)¶

Compute the local pixel to scale conversion in arcseconds.

Parameters:

cd11Series: [1, 1] element of the local Wcs affine transform in radians.
cd11Series: [1, 1] element of the local Wcs affine transform in radians.
cd12Series: [1, 2] element of the local Wcs affine transform in radians.
cd21Series: [2, 1] element of the local Wcs affine transform in radians.
cd22Series: [2, 2] element of the local Wcs affine transform in radians.

Returns:

pixScaleSeries: Arcseconds per pixel at the location of the local WC.

Navigation

ComputePixelScale¶