Calculates the derived scalars and tensors based on the 2nd and 4th order moments as defined in Rhodes, Refregier and Groth 1999 from a galaxy set. Also produces a measurement of shear based on these moments. These moments can be weighted by either a constant amount, or by a circular gaussian (as defined in RRG99).
The centroid about which the moments are taken can be given in a number of ways. The default behaviour is to measure the centroid using the zeroth moment. If the keyword FixCentroid is set, the center of the image is used. If the keyword TrueCentroid is set, the values from the data stream, usually generated by MakeGalSet, will be used.
Parameters
| Name | Type | Description |
|---|---|---|
| FixCentroid | keyword | Fix centroid to center of image. |
| TrueCentroid | keyword | Use the centroid supplied in the data stream. |
| WeightModel | string | "Constant" or "Gaussian". The weight model to use when calculating the moments. Either a constant weight or a circular gaussian. |
| Sigma | double | If using a Gaussian weight model, this is the sigma parameter in units of pixels. |
Inputs
| Name | Type | Description |
|---|---|---|
| GalSet/Width | int | Width of each image in pixels. |
| GalSet/Height | int | Height on each image in pixels. |
| GalSet/BiasedCount | int | Number of biased images in galaxy set. |
| GalSet/BiasedImages | double* | Array of pixel values of biased images. |
| GalSet/BiasedCentX | double* | If TrueCentroid is set, an array of the "true" x-coordinate of the galaxy centroid for each image. |
| GalSet/BiasedCentY | double* | If TrueCentroid is set, an array of the "true" y-coordinate of the galaxy centroid for each image. |
| GalSet/UnbiasedCount | int | Number of biased images in galaxy set. |
| GalSet/UnbiasedImages | double* | Array of pixel values of biased images. |
| GalSet/UnbiasedCentX | double* | If TrueCentroid is set, an array of the "true" x-coordinate of the galaxy centroid for each image. |
| GalSet/UnbiasedCentY | double* | If TrueCentroid is set, an array of the "true" y-coordinate of the galaxy centroid for each image. |
Outputs
| Name | Type | Description |
|---|---|---|
| RRGMoments/BiasedEps1 | double* | The first component of the spin-2 tensor of the second order moments for each biased galaxy. |
| RRGMoments/BiasedEps2 | double* | The second component of the spin-2 tensor of the second order moments for each biased galaxy. |
| RRGMoments/BiasedMu1 | double* | The first component of the spin-2 tensor of the fourth order moments for each biased galaxy. |
| RRGMoments/BiasedMu2 | double* | The second component of the spin-2 tensor of the fourth order moments for each biased galaxy. |
| RRGMoments/BiasedLam1 | double* | The scalar element derived from the fourth order moments for each biased galaxy. |
| RRGMoments/BiasedMeanGamma1 | double | The average shear bias along x-y for the entire biased galaxy set. |
| RRGMoments/BiasedMeanGamma2 | double | The average shear bias 45 degrees to x-y for the entire biased galaxy set. |
| RRGMoments/UnbiasedEps1 | double* | The first component of the spin-2 tensor of the second order moments for each unbiased galaxy. |
| RRGMoments/UnbiasedEps2 | double* | The second component of the spin-2 tensor of the second order moments for each unbiased galaxy. |
| RRGMoments/UnbiasedMu1 | double* | The first component of the spin-2 tensor of the fourth order moments for each unbiased galaxy. |
| RRGMoments/UnbiasedMu2 | double* | The second component of the spin-2 tensor of the fourth order moments for each unbiased galaxy. |
| RRGMoments/UnbiasedLam1 | double* | The scalar element derived from the fourth order moments for each unbiased galaxy. |
| RRGMoments/UnbiasedMeanGamma1 | double | The average shear bias along x-y for the entire unbiased galaxy set. |
| RRGMoments/UnbiasedMeanGamma2 | double | The average shear bias 45 degrees to x-y for the entire unbiased galaxy set. |