Source code for common.sky.background

'''
Created on 11 févr. 2019
@author: Catalano Camille, APC/IN2P3/CNRS
'''

import numpy as np

from common.io.fits_tools import read_fits
from common import add_path_data_ref_eclairs


def flat_internal_noise(noise_level=0.003, pix_area=0.4*0.4, e_min=4, e_max=120, det_shape=(80,80)):
    """
    compute the flat internal noise value in a detector shape image
    
    The internal noise is independent from wavelength
    
    :param noise_level: internal noise level in cts/s/cm2/keV (default is 0.003)
    :type noise_level: float
    :param pix_area: area of a pixel of the instrument in cm2
    :type pix_area: float
    :param e_min: energy min to integrate in keV (default is 4)
    :type e_min: float
    :param e_max: energy max to integrate in keV (default is 120)
    :type e_max: float
    :param det_shape: shape of detector
    :type det_shape: tuple
    
    :return: internal noise detector image in cts/s
    :rtype: array(float)
    """
    noise_rate = noise_level * pix_area * (e_max - e_min)   
    return np.ones(det_shape) * noise_rate 
                    
        
def flat_cxb_nospectr(cxb_level=1, pix_area=0.4*0.4, det_shape=(80,80)):
    """
    Compute a flat CXB detector image
    
    :param cxb_level: intensity of CXB
    :type cxb_level: float [count/cm2/s]
    :param pix_area: area of a pixel of the instrument in cm2
    :type pix_area: float
    :param det_shape: shape of detector
    :type det_shape: tuple
    
    :return: cxb value detector image in cts/s
    :rtype: array(float)
    """
    cxb_rate = cxb_level * pix_area
    return np.ones(det_shape) * cxb_rate


def shapebased_cxb_nospectr(cxb_level=3035, solidangle_filename=add_path_data_ref_eclairs('instru/pixels_solid_angle.fits')):
    """
    Compute a CXB detector image based on a solid angle per pixel fits image
    
    :param cxb_level: intensity of CXB in cts/s
    :type cxb_level: float
    :param solidangle_filename: PATH/filename of the solid angle image
    :type solidangle_filename: string
    
    :return: cxb rate detector image in cts/s
    :rtype: array(float)
    """
    solid_angle = read_fits(solidangle_filename, ugts_standard=1)
    cxb_rate = cxb_level * solid_angle / solid_angle.sum()
    return cxb_rate