Synthetic Photometry (m4opt.synphot)

M⁴OPT can adaptively adjust the exposure times of planned observations in order to obtain a desired signal-to-noise, given a model of the foreground signal and the observing conditions that you provide. M⁴OPT can also be used merely as a general-purpose astronomical exposure time calculator.

You specify the foreground signal and background noise using Astropy models. The m4opt.models submodule provides a curated selection of Astropy model subclasses for modeling the spectral denergy distributions of sources and the surface brightness spectrum of the sky. Models can be combined by adding, subtracting, multiplying, or dividing them.

Observing State

Some models (particularly sky background models) vary with sky position and time. You may want to leave the sky position and time unspecified when you are constructing the model, to be specified at a later point in your code, or to be specified implicitly by the scheduler. To do that, simply construct the model components directly, without any target coordinate or time. For example:

from m4opt.models.background import Airglow, ZodiacalBackground
model = Airglow() + ZodiacalBackground()

Then, when you need to evaluate the model for a _specific_ target and time, you can specify their values within a code block using a with: statement:

from m4opt.models import observing
with observing(observer_location=loc, target_coord=coord, obstime=time):
    model_value = model(1000 * u.angstrom)

See also the Examples section for ZodiacalBackground.

m4opt.synphot Package

Functions

bandpass_from_svo(filter_id)	Look up a filter bandpass from the SVO Filter Profile Service.
observing(*args, **kwargs)

Classes

Detector(plate_scale, area, bandpasses, ...)	Sensitivity calculator: compute SNR for exposure time or vice-versa.
TabularScaleFactor(array, *args, **kwargs)

Class Inheritance Diagram

m4opt.synphot.background Package

Sky background models: models of the surface brightness of the sky.

By convention, these models return the flux density integrated over a solid angle of 1 square arcsecond.

Functions

GalacticBackground()

Diffuse Galactic ultraviolet background emission.

Classes

SkyBackground()	Sky Brightness background: sky glow due to scattered and diffuse light
ZodiacalBackground()	Zodiacal light sky background: sunlight scattered by interplanetary dust.

Class Inheritance Diagram

m4opt.synphot.extinction Package

Extinction models.

Functions

DustExtinction([Ebv])

Milky Way dust extinction.