User defined profile

Here, we show how to integrate a more realistic sky profile as an example of a user-defined profile. In this new sky profile, the sky intensity is defined as follows:

\[I = I_0 + k_{\mathrm{x}}(x - x_0) + k_{\mathrm{y}}(y - y_0).\]

To integrate this new profile, we need to define a new class, which we have named NewSky. This class should include a function that guides the generation of the image model from the given parameters.

Here are some caveats.

• every profile class should inherit from the basic class LightProfile to access general light profile functions.

• the parameters should be loaded into the profile class in the __init__ function, and set as attributions (e.g., self.sky_0 = sky_0).

Define new profile

import galmoss as gm

class NewSky(gm.LightProfile):
    def __init__(self, sky_0, grad_x, grad_y):
        super().__init__()
        self.psf = False
        self.sky_0 = sky_0
        self.grad_x = grad_x
        self.grad_y = grad_y

    def image_via_grid_from(self,
                            grid,
                            mode="updating_model"):
        return (self.sky_0.value(mode)
                + self.grad_x.value(mode)
                * (grid[1]-(grid[0].shape[1] + 1)/2)
                + self.grad_y.value(mode)
                * (grid[0]-(grid[0].shape[0] + 1)/2))

The equation for the profile is defined within the image_via_grid_from function. Parameter values are extracted after the mode value, which has a default value of updating_model. This mode calls for values that are continuously updated throughout the fitting process and have already been broadcast to a suitable shape for multi-dimensional matrix calculations.

Use new profile

A newly defined profile can be used as follows:

sky = NewSky(sky_0=gm.p(0.3),
            grad_x=gm.p(2),
            grad_y=gm.p(3))