Rigel Spectrograph

Hi Kevin,

I was involved with it briefly a couple of years back. It is a grating in the converging beam similar to that commonly used with the Star Analyser or Rainbow Optics grating.  It is similar in concept to the remote system  trialed by AAVSO but with a higher dispersion giving a more useful resolution. It clearly works but personally I would have used a coarser grating with a lower dispersion angle combined with a larger grating to CCD distance which would be more efficient and give less aberration and distortion of the spectrum. This can be more difficult to engineer into an existing imaging setup though (The comments about tilting the grating make no sense to me).

With this sort of aperture and dark sky site they should be able to push the boundaries of what this sort of setup has  been shown to be capable of so far (eg down to magnitude of around mag 15-16 on supernovae currently) but the result I have seen published so far have been significantly brighter than this.  

Cheers

Robin

Kevin,

I agree with Robin's comments....

If you set-up a Rainbow Optics or a Star Analyzer grating in the converging beam and tune the distance between the grating and CCD to match your chip size, you will achieve very similar results.

A reflector based system around f5 is close to optimum for a slitless application.

Preparing for a remote operation imaging run will require the ability to re-orientate the grating/ camera to avoid background stars overlapping the spectrum. It would be very nice to see more activity on this front by AAVSO members.....

Here is a recent spectrum of Beta Eridani I obtained using the Rigel TGS for a project I am working on to observe Mintaka (Delta Orionis). As you can see the range is very wide (3500-10000 A). The measured resolution is about 800 at 5500A. The spectra has been wavelength calibrated and normalized to the CCD response.

http://www.pbase.com/jerry_hubbell/image/148297768/original

Jerry Hubbell

Lake of the Woods Observatory (MPC I24)

Author "Scientific Astrophotography: How Amateurs Can Generate and Use Professional Imaging Data"