This version of the imaging ETC assumes that you have precise requirements for the signal to noise you want to reach in imaging mode. Estimated exposure times below 60sec have been set to 60sec as we do we do not recommend to expose for less than 1 minute, except for very bright objects. Estimated exposure times above 7200sec are probably unphysical. Results will be for mean moon conditions. We give in the following the parameter ranges we tested. Values outside of these ranges will give a predicted exposure time (except for unphysical airmasses), but we suggest to carefully look at the 3D plots, as this exposure time may be affected by model divergences. model divergences.

Filter/entrance lens combinations * Choose a Filter/entrance lens combinationsg' / blue lensr' / blue lensi' / blue lensz' / red lensY / red lens

OHP seeing is typically varying between 1arcsec (not very often), and 5arcsec, with a median value close to 2.5arcsec.

Seeing *

Object type * Choose an object typePunctual objects (stars)Extended objects (distant galaxies not surface brightness dominated)

Object (modeled by a gaussian) apparent fwhm (arcsec). Only used if extended object

Object apparent fwhm

Do you want an additionnal extinction? Give a magnitude (>0.)

Gives the Air Mass (>1). Values above 2 are in unexplored domains, exposure times may be wrong (and telescope broken...).

Air Mass *

Targetted magnitude (in the required band, AB system). This version of the ETC tested values between 15 and 23, depending on the magnitude band you have chosen. Values larger than 23 are in unexplored domains, so may be wrong.

Targetted Magnitude *

Gives the required S/N. We tested values between 1.5 and 6. For values outside of this domain, exposure times may be wrong.

S/N *