To improve the sensitivity, I have remounted the 100 l/min grating closer to the CCD chip (approx 25mm) and am now using the more sensitive 1004x-JG camera. I have also incorporated the focal reducer to give approx f6.4 with the VC200L.

This means that the dispersion has been reduced to around 3nm/pixel but I believe it is now better matched to the resolution of the rest of the optics. The more concentrated spectrum and higher sensitivity camera should mean better faint object capability. First light tests look promising with mag 8 star spectra being recorded in 0.3sec and mag 12 star spectra detected with 20 sec exposures.

17th April 2004

UPDATE 26th April 2004

It has proved possible to record the spectrum of bright QSO 3C 273 see link below

Click here for a design for universal webcam grating mount, based on a modified Mogg adapter

TO FAINT OBJECT SET UP FIRST LIGHT

MEASURING THE REDSHIFT OF QUASAR 3C 273

RETURN TO SPECTROSCOPY INTRODUCTION

BACK TO ASTRONOMY HOME