Noise

The madcubapy.operations.maps.noise module contains functions to help the user estimate and work with the noise of the data in FITS files.

Measure noise

The measure_noise() function helps the user measure the noise level of a MadcubaMap or CCDData object.

The function plots the map in a pop-up window and lets the user select several polygons in which the noise will be calculated. The polygons are selected using the mouse:

• Left clicks create polygon vertices.

• Right click closes the current polygon, and a subsequent left click starts a new polygon.

Parameters

Once the window with the plotted map is opened the user can select the polygons, and also the statistic to be used for calculating the noise via GUI buttons. The user can also select the desired statistic with the statistic parameter:

• ‘std’ for standard deviation.

• ‘rms’ for root mean square.

Example Usage

>>> sigma = measure_sigma(madcuba_map, statistic='rms')
>>> sigma
42.34567

Returns

This function returns a float number: the noise calculated as the specified statistic.

Additional Parameters

This function accepts optional keyword arguments that are passed to add_wcs_axes() for visualization purposes.

>>> measure_sigma(madcuba_map, vmin=0, vmax=100)