signal_to_noise_to_exp_time#

arcesetc.signal_to_noise_to_exp_time(sptype, wavelength, V, signal_to_noise)[source]#

Compute the exposure time required to collect signal-to-noise ratio signal_to_noise at wavelength wavelength for a star of spectral type sptype and V magnitude V.

Warning

arcesetc doesn’t know anything about saturation. Ye be warned!

Parameters:

sptypestr: Spectral type of the star.
wavelengthQuantity: Wavelength of interest.
Vfloat: V magnitude of the target.
signal_to_noisefloat: If signal_to_noise is a float, compute the appropriate exposure time to generate the S/N curve that has S/N = signal_to_noise at wavelength wavelength. Otherwise, generate S/N curve for exposure time exp_time.

Returns:

exp_timeQuantity: Exposure time input, or computed to achieve S/N ratio signal_to_noise at wavelength wavelength.

Examples

How many seconds must one expose ARCES on a V=12 mag M0V star to get a S/N of 30 at the wavelength of H-alpha?

>>> from arcesetc import signal_to_noise_to_exp_time
>>> import astropy.units as u
>>> sptype = 'M0V'
>>> wavelength = 6562 * u.Angstrom
>>> signal_to_noise = 30
>>> V = 12
>>> print(signal_to_noise_to_exp_time(sptype, wavelength, V, signal_to_noise)) 
642.11444 s