ExpCalculator

Exposure Time Calculator
Marek Gorski
28.07.2022

ToDo:

• passband efficiency
• other bands (I,J,H,K)

Reguirements: python3, numpy, scipy

Calculations:

Aperture = 2 * seeing

background:

pixel_size_coefficient = (pix_size / reference_pix_size)^2
background_per_pix = (dark + sky_background * pixel_size_coefficient ) * exp_time
number_of_pix_in_aperture = 3.14 * 2 * (seeing / pix_size)^2
background_in_aperture (2 * seeing) = background_per_pix * number_of_pix_in_apertur

star ADU:
reference_star_radiation
magnitude_coefficient = 10^(reference_m - magnitude)/2.5
mirror_coefficient = (mirror_size/reference_mirror_size)^2
star_ADU = reference_star_radiation * magnitude_coefficient * mirror_coefficient * exp_time

noise:
noise = sqrt(background_in_aperture + star_ADU) + readout_noise

Signal to Noise:
sn = star_ADU / noise

Pixel Saturation:
sigma_coe = pix_size / (seeing/2.355) <-- fwhm=2.355 /* sigma
coe_norm = CDF(sigma_coe)-CDF(-1*sigma_coe)
central_pixel_ADU = background_per_pix + star_ADU /* coe_norm