Point Source

If we consider for example a point source with a uniform emission of magnitude 15 in the band V, at 0 days from new moon, being the sky airmass 1.2, and a seeing of 0.5, with no filter inserted, in slow read out mode, with a binning of $1\times 1$ for an integration time of 60 seconds, we could get:

$$M_{V}=15\Longrightarrow Z_{V}=7.4425\Longrightarrow F=3.60994013586\cdot 10^{-14} ~J\cdot s^{-1}\cdot m^{-2}\cdot \mu m^{-1}$$

where we have used data in Tab. 2.3 and eq. (2.5), (2.6) and expressed the result in Joule units.

Using eq. (2.7):

$$P=\frac{h\cdot c}{\lambda}=3.61\overline{09}\cdot10^{-19} J\slash ph\hbox{ at $\lambda=0.55~\mu m$}$$

$$\displaystyle\left(\frac{F}{P}\right)_{Obj}=9.99731658974\cdot 10^{4}~ph\cdot s^{-1}\cdot m^{-2}\cdot\mu m^{-1}$$

$$\Delta_{i}=0.125\cdot 10^{-3} ~\mu m$$

S=8.9  m²

T=60  s

E=0.365

With the previously specified parameter we can get from formulae in Tab. 2.1:

$$N_{Obj}=\frac{F\cdot \Delta_{i}\cdot T\cdot E\cdot S}{P}=2.43572122064\cdot10^{6} ~cnts$$ (2.17)

The ETC for SUSI2 with the input parameter as specified above predicts $N_{ETC}=2.25901391\cdot10^{6}$ cnts.