Astronomical Functions

Magnitude and Flux Calculations

aotools.astronomy.flux_to_magnitude(flux, waveband='V')[source]

Converts incident flux of photons to the apparent magnitude

Parameters:

  • flux (float) – Number of photons received from an object per second per meter squared

  • waveband (string) – Waveband of the measured flux, can be U, B, V, R, I, J, H, K, g, r, i, z

Returns:

Apparent magnitude

Return type:

float

aotools.astronomy.magnitude_to_flux(magnitude, waveband='V')[source]

Converts apparent magnitude to a flux of photons

Parameters:

  • magnitude (float) – Star apparent magnitude

  • waveband (string) – Waveband of the stellar magnitude, can be U, B, V, R, I, J, H, K, g, r, i, z

Returns:

Number of photons emitted by the object per second per meter squared

Return type:

float

aotools.astronomy.photons_per_band(mag, mask, pxlScale, expTime, waveband='V')[source]

Calculates the photon flux for a given aperture, star magnitude and wavelength band

Parameters:

  • mag (float) – Star apparent magnitude

  • mask (ndarray) – 2-d pupil mask array, 1 is transparent, 0 opaque

  • pxlScale (float) – size in metres of each pixel in mask

  • expTime (float) – Exposure time in seconds

  • waveband (string) – Waveband

Returns:

number of photons

Return type:

float

aotools.astronomy.photons_per_mag(mag, mask, pixel_scale, wvlBand, exposure_time)[source]

Calculates the photon flux for a given aperture, star magnitude and wavelength band

Parameters:

  • mag (float) – Star apparent magnitude

  • mask (ndarray) – 2-d pupil mask array, 1 is transparent, 0 opaque

  • pixel_scale (float) – size in metres of each pixel in mask

  • wvlBand (float) – length of wavelength band in nanometres

  • exposure_time (float) – Exposure time in seconds

Returns:

number of photons

Return type:

float