draw

draw.star(grid_size, radius=0.5, limb_darkening_law=None, ld_coefficient=None, custom_limb_darkening=None, supersampling=None, upscaling=None, resample_method=None)

Make a normalized drawing of a star with a corresponding limb-darkening law in a square grid. The normalization is made in such a way that the flattened sum of the values inside the two-dimensional array is equal to 1.0. The normalization factor is calculated before the resampling, so more complex resampling algorithms may produce more inaccurate normalizations (by a factor of a few to hundreds of ppm) depending on the requested grid size and supersampling factor. If very precise normalized maps are required, then it is better to not use supersampling or use a "box" resampling algorithm.

Parameters

grid_size (``int``):

Size of the square grid in number pixels.

radius (``int`` or ``float``, optional):

Stellar radius in units of grid_size. Default is 0.5.

limb_darkening_law (``None`` or ``str``, optional):

String with the name of the limb-darkening law. The options currently implemented are: 'linear', 'quadratic', 'square-root', 'logarithmic' (or 'log'), 'exponential' (or 'exp'), 'sing-three' (or 'sing', or 's3'), 'claret-four' (or 'claret', or 'c4'), None (no limb-darkening), or 'custom'. In case you choose the latter, you need to provide a callable function that defines your custom law using the parameter custom_limb_darkening. Default is None.

ld_coefficient (``float`` or ``array-like``):

In case of a linear limb-darkening law, the value of the coefficient should be a float. In all other options it should be array-like. Default is None.

custom_limb_darkening (``callable`` or ``None``, optional)

In case you want to use a custom limb-darkening law, you need provide a function that defines it. The first parameter of this function must be mu (cosine of the angle between a line normal to the stellar surface and the line of sight), and the second must be the coefficient (in case it uses multiple coefficients, it must accept them as an array-like object). Default is None.

supersampling (``int``, ``float``, or ``None``, optional):

For low-resolution grid sizes, in order to avoid intensity maps with hard edges, you can supersample the array by a certain factor defined by this parameter, and then the map is downscaled to your requested grid size using the algorithm defined in resample_method. Default is None (no supersampling).

upscaling (``int``, ``float``, or ``None``, optional):

For fast output of high-resolution grids, you may want to upscale them from a low-resolution setup to save about one order of magnitude in computation time. This parameter is the factor by which to upscale the grids to match the requested grid size. The resizing algorithm is defined in resample_method. Default is None (no upscaling).

resample_method (``str`` or ``None``, optional):

Resampling algorithm. The options currently available are: "nearest", "box", "bilinear", "hamming", "bicubic", and "lanczos". If None, then fallback to "box". Default is None.

Returns

grid (flatstar.utils.StarGrid object):

Intensity map of the star.

draw.planet_transit(star_grid, planet_to_star_ratio, impact_parameter=0.0, phase=0.0, rescaling_factor=None, resample_method=None)

Draw a transit in the StarGrid object.

Parameters

star_grid (``flatstar.utils.StarGrid`` object):

planet_to_star_ratio (``float``):

Ratio between the radii of the planet and the star.

impact_parameter (``float``, optional):

Impact parameter of the transit in units of stellar radii. Default is 0.

phase (``float``, optional):

Phase of the transit. -0.5, 0.0, and +0.5 correspond respectively to the time of first contact, transit mid-center, and time of fourth contact. Default is 0.

rescaling_factor (``float`` or ``None``, optional)

Resize the grid by a factor defined by this parameter. If None, no resizing is performed. Default is None.

resample_method (``str`` or ``None``, optional):

Resampling algorithm. The options currently available are: "nearest", "box", "bilinear", "hamming", "bicubic", and "lanczos". If None, then fallback to "box". Default is None.

Returns

star_grid (flatstar.utils.StarGrid object):

Updated StarGrid object containing the transit.