6.7 Post-Helium Flux Calibration Sources

Table 6.1 shows the calibration stars used for the calibration of the RSRF and the flux calibration of the observations obtained during the Post-Helium Phase.

Table 6.1: The calibration stars used for deriving the Relative Spectral Response Function and flux calibration of the Post-Helium Phase

Source	Sp. Type	# obs
$\alpha$ Lyr	A0 VA	6
$\delta$ Dra	G9 III	7
$\gamma$ Dra	K5 III	3

The reference SED used for $\alpha$ Lyr was a composite spectrum by Cohen et al. 1992a, [2] while the synthetic spectra for $\delta$ Dra and $\gamma$ Dra were taken from Decin 2000, [4]. These synthetic spectra are based on the SOS-MARCS model atmosphere code (Gustafsson et al. 1975, [12]) and were generated using the TurboSpectrum programme (Plez, Brett & Nordlund 1992, [31]).

The following fundamental stellar parameters were used for $\delta$ Dra: T$_{eff}$ = 4820 K; log g = 2.90; $\xi_t$ = 1.7 km/s; [Fe/H] = 0.00; $\epsilon$(C) = 8.25; $\epsilon$(N) = 8.26; $\epsilon$(O) = 8.83; $^{12}$C/$^{13}$C = 12; $\theta_d$ = 3.31 mas.

In the case of $\gamma$ Dra the parameters used were: T$_{eff}$ = 3930 K; log g = 1.55; $\xi_t$ = 2.0km/s; [Fe/H] = 0.00; $\epsilon$(C) = 8.22; $\epsilon$(N) = 8.26; $\epsilon$(O) = 8.81; $^{12}$C/$^{13}$C = 10; $\theta_d$ = 10.07 mas.