Defining target brightness

All targets with separate spectral information (basically anything except a full datacube) usually also need some information on how to scale the spectrum. The only exception to this are user-supplied spectra, which are already flux-calibrated to the desired level.

Nomenclature

The name brightness was chosen as the least ambiguous of several rejected alternatives and because it matched with the ESO standard. It is not usually associated with any particular unit or physical type, but rather more of a general “how bright is my source”.

Rejected alternatives

Some of these were used in ScopeSim_Templates, with no particular standard.

Magnitude

Physical flux units can also be used to specify brightness. Calling it magnitude would suggest it only accepts magnitudes.

Flux

The opposite as with magnitude, this would suggest using a magnitude value is not supported.

Amplitude

This name seems more fitting for the scaling of normalized profiles, can be confusing for point sources.

Luminosity

The second-best alternative, but still more associated with specific units, like $L_\odot$.

Possible way to specify brightness

Band, Magnitude

Currently the only implemented way to specify target brightness. Consists of a 2-tuple with a string identifying the bandpass (“filter”) in which the magnitude is given, and a numerical value or astropy.Quantity in u.mag. In this case, mag refers to Vega magnitudes, ABmag and STmag will be implemented in a future version.

Band, Flux

To be implemented.

Wavelength, Flux

To be implemented.

Frequency, Flux

To be implemented.

To be discussed

Brightness from spectral type?

Absolute magnitudes?

Surface brightness vs integrated brightness?