Template Spectra

6 different model spectra representing various main sequence stars are available. These are [STERNS]: B0V, A0V, F0V, G0V, K0V, M0V (Figure 2).

Figure 2: The six available stellar spectra

Their flux densities are normalized to

f($\displaystyle \lambda$ = 550 nm) = 3.66 . 10-11 W m-2 nm-1 (11)

In addition, 4 different galaxy template spectra are available (Figure 3 and [GALAXS]). If a spectrum is allowed to be redshifted the filename must include the phrase 'galaxy' at any position.

Figure 3: The four available galaxy spectra at redshift z=0.

The transformed spectra are calculated by the definition of the redshift:

z = $\displaystyle {\frac{{\lambda - \lambda_0}}{{\lambda_0}}}$  $\displaystyle \rightarrow$  $\displaystyle \lambda$ = (z + 1)$\displaystyle \lambda_{0}^{}$ (12)

z : redshift
$ \lambda$ : measured wavelength
$ \lambda_{0}^{}$ : rest wavelength

Finally, a uniform spectrum can be used. The first step of creating such a spectrum (constant flux density for all wavelengths) is to calculate the total flux (in the given band-pass) for a uniform spectrum with an arbitrary flux density. After that the flux is calibrated to the target magnitude given by the user.

Andre Germeroth 2016-11-04