Department of Physics

AstroLab

Exposure Time Calculator

Magnitude: Seeing ("): Zenith Angle (deg): Exposure Time (s): 0.03 0.05 0.1 0.2 0.3 0.5 1 2 4 8 15 30 60 120 Filter: B V R C Telescope: draco2 east-16 far-east-20 west-14 pt5m Sky Background: Dark Grey Bright Cloud Cover: Photometric Thin Thick

This webpage calculates an estimate of the total counts, peak counts and signal to noise ratio, if a star was observed for the conditions specified. The SNR should be maximised but without exceeding the detector's linearity limit. Expected magnitudes are approximately 7-18. Typical seeing conditions are 1-5 arcseconds. The zenith angle is measured downwards from the zenith with the horizon at 90 degrees. The sky background level is dictated predominantly by the position and phase of the moon.