Exposure time calculator

The current exposure time calculator has been implemented using the zeropoints shown in the MEIA2 and ARES web pages. Similar values should be applicable to LAIA. The zeropoints provide an estimate of the limiting magnitude for an exposure time of 5 minutes (the maximum recommended) and S/N=100. They are based on observations in dark-clear nights with medium seeing for objects at zenith. Therefore, the results presented below do not consider sky brightness (around V~22 mag per arcsec) and should be considered orientative at best.

In order to determine the maximum exposure time before saturation with LAIA, values with a S/N=750 should ensure an optimum S/N within linearity regime of the CCD, except in cases with very good seeing or bright sky conditions.

Instrument 
Value to compute 
Filter 
Apparent magnitude 
Exposure time (sec) 
S/N ratio 
VPH 
Magnitude of the star 
Exposure time (sec)