Hi Andy,

#576962
Robin Leadbeater
Participant

Hi Andy,

Hmm.. getting an even enough flat might take some arranging. I think you would need to go back to a flat light source in front of the telescope rather than rely on the internal flat lamp, to take into accout any vignetting before the spectrograph.  You could perhaps test it though by taking a daylight sky spectrum which over the small field should give  the same counts independent of position along the slit, once flat corrected.

Robin