interactive_lower_threshold

threadcount.fit.interactive_lower_threshold(image, title='')[source]

Create plot and interact with user to determine the lower threshold for valid data.

The image is plotted, with a mask applied which initially masks the lower 95% of data. A prompt is given in the console, asking for user input. If the user enters no input and presses <enter>, that indicates the currently shown level has been accepted by the user. Otherwise, the user may input a different number. The plot will be redrawn and the input is requested again.

This function is primarily used to determine the cutoff indicating the spaxels containing the most flux, hopefully indicating the galaxy center. We then will use those pixels to fit an emission line, and find the centers. This can be used to tweak the redshift if desired.

Parameters:

  • image (mpdaf.obj.Image) – An mpdaf image we wish to threshold interactively

  • title (str, optional) – The title given to the plot displaying the image, by default “”

Returns:

limit – The deterimined threshold for valid data.

Return type:

float