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Exposure time calculator

The current, preliminary exposure time calculator has been implemented using the zeropoints shown in the MEIA web page. The zeropoints provide an orientative estimate of the limiting magnitude for an exposure time of 5 minutes (the maximum recommended) and S/N=100. The sky conditions cannot be configured and assume that observations are performed in a dark-clear night with medium seeing for objects at zenith. Therefore, the results presented below should be considered orientative at best.

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

Value to compute 


Apparent magnitude 

Exposure time (sec) 

S/N ratio