Here is a study of the HeII4686 profile variation depending of the exposure time of WR134, a wolf rayet star subject of a 2013 pro am campaign from the Convento group
The SNR requirement on 1hour exposure for this campaign is about 200. The resolution must be better than 1A, R5000 at HeII4686.
Here is an individual order of an echelle spectra taken during the night of Dec, 12th. The sky conditions were excellent and the object was at 80° high at the beginning of exposures. 2H40 exposure were taken, under good seing and transparency.
Resolving power is 10000 and dispersion 0.1A. Unfortunately a SNR of 200 cannot be reach with my principal instrument (0.35m f5 schmidt cassegrain, fiber feed eshell spectroscope, ST10XME camera) in one hour. The snr of my best spectrum is about 20 at the position 4733A.
Note the evolution of the intensitie for the longuest exposure, same date. Spectra are not normalized but rescaled to fit the continuum at 1.
Standart pre processing (Bias, Dark, flatfield) and spectra reduction under Audela Calibration on a thor arg lamp
Spectra fit files 20111212_173246_WR134_HeII4686_TGarrel